Tag Archives: Northwestern University

100-fold increase in AI energy efficiency

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Most people don’t realize how much energy computing, streaming video, and other technologies consume and AI (artificial intelligence) consumes a lot. (For more about work being done in this area, there’s my October 13, 2023 posting about an upcoming ArtSci Salon event in Toronto featuring Laura U. Marks’s recent work ‘Streaming Carbon Footprint’ and my October 16, 2023 posting about how much water is used for AI.)

So this news is welcome, from an October 12, 2023 Northwestern University news release (also received via email and on EurekAlert), Note: Links have been removed,

AI just got 100-fold more energy efficient

Nanoelectronic device performs real-time AI classification without relying on the cloud

– AI is so energy hungry that most data analysis must be performed in the cloud
– New energy-efficient device enables AI tasks to be performed within wearables
– This allows real-time analysis and diagnostics for faster medical interventions
– Researchers tested the device by classifying 10,000 electrocardiogram samples
– The device successfully identified six types of heart beats with 95% accuracy

Northwestern University engineers have developed a new nanoelectronic device that can perform accurate machine-learning classification tasks in the most energy-efficient manner yet. Using 100-fold less energy than current technologies, the device can crunch large amounts of data and perform artificial intelligence (AI) tasks in real time without beaming data to the cloud for analysis.

With its tiny footprint, ultra-low power consumption and lack of lag time to receive analyses, the device is ideal for direct incorporation into wearable electronics (like smart watches and fitness trackers) for real-time data processing and near-instant diagnostics.

To test the concept, engineers used the device to classify large amounts of information from publicly available electrocardiogram (ECG) datasets. Not only could the device efficiently and correctly identify an irregular heartbeat, it also was able to determine the arrhythmia subtype from among six different categories with near 95% accuracy.

The research was published today (Oct. 12 [2023]) in the journal Nature Electronics.

“Today, most sensors collect data and then send it to the cloud, where the analysis occurs on energy-hungry servers before the results are finally sent back to the user,” said Northwestern’s Mark C. Hersam, the study’s senior author. “This approach is incredibly expensive, consumes significant energy and adds a time delay. Our device is so energy efficient that it can be deployed directly in wearable electronics for real-time detection and data processing, enabling more rapid intervention for health emergencies.”

A nanotechnology expert, Hersam is Walter P. Murphy Professor of Materials Science and Engineering at Northwestern’s McCormick School of Engineering. He also is chair of the Department of Materials Science and Engineering, director of the Materials Research Science and Engineering Center and member of the International Institute of Nanotechnology. Hersam co-led the research with Han Wang, a professor at the University of Southern California, and Vinod Sangwan, a research assistant professor at Northwestern.

Before machine-learning tools can analyze new data, these tools must first accurately and reliably sort training data into various categories. For example, if a tool is sorting photos by color, then it needs to recognize which photos are red, yellow or blue in order to accurately classify them. An easy chore for a human, yes, but a complicated — and energy-hungry — job for a machine.

For current silicon-based technologies to categorize data from large sets like ECGs, it takes more than 100 transistors — each requiring its own energy to run. But Northwestern’s nanoelectronic device can perform the same machine-learning classification with just two devices. By reducing the number of devices, the researchers drastically reduced power consumption and developed a much smaller device that can be integrated into a standard wearable gadget.

The secret behind the novel device is its unprecedented tunability, which arises from a mix of materials. While traditional technologies use silicon, the researchers constructed the miniaturized transistors from two-dimensional molybdenum disulfide and one-dimensional carbon nanotubes. So instead of needing many silicon transistors — one for each step of data processing — the reconfigurable transistors are dynamic enough to switch among various steps.

“The integration of two disparate materials into one device allows us to strongly modulate the current flow with applied voltages, enabling dynamic reconfigurability,” Hersam said. “Having a high degree of tunability in a single device allows us to perform sophisticated classification algorithms with a small footprint and low energy consumption.”

To test the device, the researchers looked to publicly available medical datasets. They first trained the device to interpret data from ECGs, a task that typically requires significant time from trained health care workers. Then, they asked the device to classify six types of heart beats: normal, atrial premature beat, premature ventricular contraction, paced beat, left bundle branch block beat and right bundle branch block beat.

The nanoelectronic device was able to identify accurately each arrhythmia type out of 10,000 ECG samples. By bypassing the need to send data to the cloud, the device not only saves critical time for a patient but also protects privacy.

“Every time data are passed around, it increases the likelihood of the data being stolen,” Hersam said. “If personal health data is processed locally — such as on your wrist in your watch — that presents a much lower security risk. In this manner, our device improves privacy and reduces the risk of a breach.”

Hersam imagines that, eventually, these nanoelectronic devices could be incorporated into everyday wearables, personalized to each user’s health profile for real-time applications. They would enable people to make the most of the data they already collect without sapping power.

“Artificial intelligence tools are consuming an increasing fraction of the power grid,” Hersam said. “It is an unsustainable path if we continue relying on conventional computer hardware.”

…

Here’s a link to and a citation for the paper,

Reconfigurable mixed-kernel heterojunction transistors for personalized support vector machine classification by Xiaodong Yan, Justin H. Qian, Jiahui Ma, Aoyang Zhang, Stephanie E. Liu, Matthew P. Bland, Kevin J. Liu, Xuechun Wang, Vinod K. Sangwan, Han Wang & Mark C. Hersam. Nature Electronics (2023) DOI: https://doi.org/10.1038/s41928-023-01042-7 Published: 12 October 2023

This paper is behind a paywall.

Sponge coated with nanoparticles removes lead from water

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It doesn’t look like much but who cares when it does the job and is being made available commercially,

Caption: Commercially available cellulose sponge coated in manganese-doped goethite nanoparticles. Credit: Caroline Harms/Northwestern University

A May 11, 2023 news item on Nanowerk announces the research,

Northwestern University engineers have developed a new sponge that can remove metals — including toxic heavy metals like lead and critical metals like cobalt — from contaminated water, leaving safe, drinkable water behind.

In proof-of-concept experiments, the researchers tested their new sponge on a highly contaminated sample of tap water, containing more than 1 part per million of lead. With one use, the sponge filtered lead to below detectable levels.

After using the sponge, researchers also were able to successfully recover metals and reuse the sponge for multiple cycles. The new sponge shows promise for future use as an inexpensive, easy-to-use tool in home water filters or large-scale environmental remediation efforts.

…

A May 10, 2023 Northwestern University news release on EurekAlert (also received via email) provides more detail, Note: Links have been removed,

The study was published late yesterday (May 10 [2023]) in the journal ACS ES&T Water. The paper outlines the new research and sets design rules for optimizing similar platforms for removing — and recovering — other heavy-metal toxins, including cadmium, arsenic, cobalt and chromium.

“The presence of heavy metals in the water supply is an enormous public health challenge for the entire globe,” said Northwestern’s Vinayak Dravid, senior author of the study. “It is a gigaton problem that requires solutions that can be deployed easily, effectively and inexpensively. That’s where our sponge comes in. It can remove the pollution and then be used again and again.”

Dravid is the Abraham Harris Professor of Materials Science and Engineering at Northwestern’s McCormick School of Engineering and director of global initiatives at the International Institute for Nanotechnology.

Sopping up spills

The project builds on Dravid’s previous work to develop highly porous sponges for various aspects of environmental remediation. In May 2020, his team unveiled a new sponge designed to clean up oil spills. [Note: My June 25, 2020 posting highlights the work and includes an embedded video demonstration of the technology.] The nanoparticle-coated sponge, which is now being commercialized by Northwestern spinoff MFNS Tech, offers a more efficient, economic, ecofriendly and reusable alternative to current approaches to oil spills.

But Dravid knew it wasn’t enough.

“When there is an oil spill, you can remove the oil,” he said. “But there also are toxic heavy metals — like mercury, cadmium, sulfur and lead — in those spills. So, even when you remove the oil, some of the other toxins might remain.

Rinse and repeat

To tackle this aspect of the issue, Dravid’s team, again, turned to sponges coated with an ultrathin layer of nanoparticles. After testing many different types of nanoparticles, the team found that a manganese-doped goethite coating worked best. Not only are manganese-doped goethite nanoparticles inexpensive to make, easily available and nontoxic to human, they also have the properties necessary to selectively remediate heavy metals.

“You want a material with a high surface area, so there’s more room for the lead ions to stick to it,” said Benjamin Shindel, a Ph.D. student in Dravid’s lab and the paper’s first author. “These nanoparticles have high-surface areas and abundant reactive surface sites for adsorption and are stable, so they can be reused many times.”

The team synthesized slurries of manganese-doped goethite nanoparticles, as well as several other compositions of nanoparticles, and coated commercially available cellulose sponges with these slurries. Then, they rinsed the coated sponges with water in order to wash away any loose particles. The final coatings measured just tens of nanometers in thickness.

When submerged into contaminated water, the nanoparticle-coated sponge effectively sequested lead ions. The U.S. Food and Drug Administration requires that bottled drinking water is below 5 parts per billion of lead. In filtration trials, the sponge lowered the amount of lead to approximately 2 parts per billion, making it safe to drink.

“We’re really happy with that,” Shindel said. “Of course, this performance can vary based on several factors. For instance, if you have a large sponge in a tiny volume of water, it will perform better than a tiny sponge in a huge lake.”

Recovery bypasses mining

From there, the team rinsed the sponge with mildly acidified water, which Shindel likened to “having the same acidity of lemonade.” The acidic solution caused the sponge to release the lead ions and be ready for another use. Although the sponge’s performance declined after the first use, it still recovered more than 90% of the ions during subsequent use cycles.

This ability to gather and then recover heavy metals is particularly valuable for removing rare, critical metals, such as cobalt, from water sources. A common ingredient in lithium-ion batteries, cobalt is energetically expensive to mine and accompanied by a laundry list of environmental and human costs.

If researchers could develop a sponge that selectively removes rare metals, including cobalt, from water, then those metals could be recycled into products like batteries.

“For renewable energy technologies, like batteries and fuel cells, there is a need for metal recovery,” Dravid said. “Otherwise, there is not enough cobalt in the world for the growing number of batteries. We must find ways to recover metals from very dilute solutions. Otherwise, it becomes poisonous and toxic, just sitting there in the water. We might as well make something valuable with it.”

Standardized scale

As a part of the study, Dravid and his team set new design rules to help others develop tools to target particular metals, including cobalt. Specifically, they pinpointed which low-cost and nontoxic nanoparticles also have high-surface areas and affinities for sticking to metal ions. They studied the performance of coatings of manganese, iron, aluminum and zinc oxides on lead adsorption. Then, they established relationships between the structures of these nanoparticles and their adsorptive properties.

Called Nanomaterial Sponge Coatings for Heavy Metals (or “Nano-SCHeMe”), the environmental remediation platform can help other researchers differentiate which nanomaterials are best suited for particular applications.

“I’ve read a lot of literature that compares different coatings and adsorbents,” said Caroline Harms, an undergraduate student in Dravid’s lab and paper co-author. “There really is a lack of standardization in the field. By analyzing different types of nanoparticles, we developed a comparative scale that actually works for all of them. It could have a lot of implications in moving the field forward.”

Dravid and his team imagine that their sponge could be used in commercial water filters, for environmental clean-up or as an added step in water reclamation and treatment facilities.

“This work may be pertinent to water quality issues both locally and globally,” Shindel said. “We want to see this out in the world, where it can make a real impact.”

The study, “Nano-SCHeME: Nanomaterial Sponge Coatings for Heavy Metals, an environmental remediation platform,” was supported by the National Science Foundation and U.S. Department of Energy.

Editor’s note: Dravid and Northwestern have financial interests (equities, royalties) in MFNS Tech.

Here’s a link to and a citation for the paper,

Nano-SCHeme: Nanomaterial Sponge Coatings for Heavy Metals, an Environmental Remediation Platform by Benjamin Shindel, Stephanie M. Ribet, Caroline Harms, Vikas Nandwana, and Vinayak P. Dravid. ACS EST Water 2023, XXXX, XXX, XXX-XXX DOI: https://doi.org/10.1021/acsestwater.2c00646 Publication Date:May 10, 2023 © 2023 American Chemical Society

This paper is behind a paywall.

You can find the MFNS Tech website here.

Treating cardiac arrhythmia with light: a graphene tattoo

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An April 17, 2023 news item on Nanowerk announced research into a graphene cardiac implant/tattoo,

Researchers led by Northwestern University and the University of Texas at Austin (UT) have developed the first cardiac implant made from graphene, a two-dimensional super material with ultra-strong, lightweight and conductive properties.

Similar in appearance to a child’s temporary tattoo, the new graphene “tattoo” implant is thinner than a single strand of hair yet still functions like a classical pacemaker. But unlike current pacemakers and implanted defibrillators, which require hard, rigid materials that are mechanically incompatible with the body, the new device softly melds to the heart to simultaneously sense and treat irregular heartbeats. The implant is thin and flexible enough to conform to the heart’s delicate contours as well as stretchy and strong enough to withstand the dynamic motions of a beating heart.

…

Caption: Graphene implant on tattoo paper. Credit: Ning Liu/University of Texas at Austin

An April 17, 2023 Northwestern University news release (also on EurekAlert), which originated the news item, provides more detail about the research, graphene, and the difficulties of monitoring a beating heart, Note: Links have been removed,

After implanting the device into a rat model, the researchers demonstrated that the graphene tattoo could successfully sense irregular heart rhythms and then deliver electrical stimulation through a series of pulses without constraining or altering the heart’s natural motions. Even better: The technology also is optically transparent, allowing the researchers to use an external source of optical light to record and stimulate the heart through the device.

The study will be published on Thursday (April 20 [2023]) in the journal Advanced Materials. It marks the thinnest known cardiac implant to date.

“One of the challenges for current pacemakers and defibrillators is that they are difficult to affix onto the surface of the heart,” said Northwestern’s Igor Efimov, the study’s senior author. “Defibrillator electrodes, for example, are essentially coils made of very thick wires. These wires are not flexible, and they break. Rigid interfaces with soft tissues, like the heart, can cause various complications. By contrast, our soft, flexible device is not only unobtrusive but also intimately and seamlessly conforms directly onto the heart to deliver more precise measurements.”

An experimental cardiologist, Efimov is a professor of biomedical engineering at Northwestern’s McCormick School of Engineering and professor of medicine at Northwestern University Feinberg School of Medicine. He co-led the study with Dmitry Kireev, a research associate at UT. Zexu Lin, a Ph.D. candidate in Efimov’s laboratory, is the paper’s first author.

Miracle material

Known as cardiac arrhythmias, heart rhythm disorders occur when the heart beats either too quickly or too slowly. While some cases of arrhythmia are not serious, many cases can lead to heart failure, stroke and even sudden death. In fact, complications related to arrythmia claim about 300,000 lives annually in the United States. Physicians commonly treat arrhythmia with implantable pacemakers and defibrillators that detect abnormal heartbeats and then correct rhythm with electrical stimulation. While these devices are lifesaving, their rigid nature may constrain the heart’s natural motions, injure soft tissues, cause temporary discomfort and induce complications, such as painful swelling, perforations, blood clots, infection and more.

With these challenges in mind, Efimov and his team sought to develop a bio-compatible device ideal for conforming to soft, dynamic tissues. After reviewing multiple materials, the researchers settled on graphene, an atomically thin form of carbon. With its ultra-strong, lightweight structure and superior conductivity, graphene has potential for many applications in high-performance electronics, high-strength materials and energy devices.

“For bio-compatibility reasons, graphene is particularly attractive,” Efimov said. “Carbon is the basis of life, so it’s a safe material that is already used in different clinical applications. It also is flexible and soft, which works well as an interface between electronics and a soft, mechanically active organ.”

Hitting a beating target

At UT, study co-authors Dimitry Kireev and Deji Akinwande were already developing graphene electronic tattoos (GETs) with sensing capabilities. Flexible and weightless, their team’s e-tattoos adhere to the skin to continuously monitor the body’s vital signs, including blood pressure and the electrical activity of the brain, heart and muscles.

But, while the e-tattoos work well on the skin’s surface, Efimov’s team needed to investigate new methods to use these devices inside the body — directly onto the surface of the heart.

“It’s a completely different application scheme,” Efimov said. “Skin is relatively dry and easily accessible. Obviously, the heart is inside the chest, so it’s difficult to access and in a wet environment.”

The researchers developed an entirely new technique to encase the graphene tattoo and adhere it to the surface of a beating heart. First, they encapsulated the graphene inside a flexible, elastic silicone membrane — with a hole punched in it to give access to the interior graphene electrode. Then, they gently placed gold tape (with a thickness of 10 microns) onto the encapsulating layer to serve as an electrical interconnect between the graphene and the external electronics used to measure and stimulate the heart. Finally, they placed it onto the heart. The entire thickness of all layers together measures about 100 microns in total.

The resulting device was stable for 60 days on an actively beating heart at body temperature, which is comparable to the duration of temporary pacemakers used as bridges to permanent pacemakers or rhythm management after surgery or other therapies.

Optical opportunities

Leveraging the device’s transparent nature, Efimov and his team performed optocardiography — using light to track and modulate heart rhythm — in the animal study. Not only does this offer a new way to diagnose and treat heart ailments, the approach also opens new possibilities for optogenetics, a method to control and monitor single cells with light. 

While electrical stimulation can correct a heart’s abnormal rhythm, optical stimulation is more precise. With light, researchers can track specific enzymes as well as interrogate specific heart, muscle or nerve cells.

“We can essentially combine electrical and optical functions into one biointerface,” Efimov said. “Because graphene is optically transparent, we can actually read through it, which gives us a much higher density of readout.”

…

The University of Texas at Austin issued an April 18, 2023 news release and as you would expect the focus is on their researchers, Note 1: I’ve removed many but not all of the redundancies between the two news releases; Note 2: A link has been removed,

A new cardiac implant made from graphene, a two-dimensional super material with ultra-strong, lightweight and conductive properties, functions like a classic pacemaker with some major improvements.

A team led by researchers from The University of Texas at Austin and Northwestern University developed the implantable derivative from wearable graphene-based electronic tattoo, or e-tattoo – graphene biointerface. The device, detailed in the journal Advanced Materials, marks the thinnest known cardiac implant to date.

“It’s very exciting to take our e-tattoo technology and use it as an implantable device inside the body,” said Dmitry Kireev, a postdoctoral research associate in the lab of professor Deji Akinwande’s lab at UT Austin who co-led the research. “The fact that is much more compatible with the human body, lightweight, and transparent, makes this a more natural solution for people dealing with heart problems.”

…

Hitting a beating target

At UT Austin, Akinwande and his team had been developing e-tattoos using graphene for several years, with a variety of functions, including monitoring body signals. Flexible and weightless, their team’s e-tattoos adhere to the skin to continuously monitor the body’s vital signs, including blood pressure and the electrical activity of the brain, heart and muscles.

But, while the e-tattoos work well on the skin’s surface, the researchers needed to find new ways to deploy these devices inside the body — directly onto the surface of the heart.

“The conditions inside the body are very different compared to affixing a device to the skin, so we had to re-imagine how we package our e-tattoo technology,” said Akinwande, a professor in the Chandra Family Department of Electrical and Computer Engineering.  

The researchers developed an entirely new technique to encase the graphene tattoo and adhere it to the surface of a beating heart. …

Here’s a link to and a citation for the paper,

Graphene Biointerface for Cardiac Arrhythmia Diagnosis and Treatment by Zexu Lin, Dmitry Kireev, Ning Liu, Shubham Gupta, Jessica LaPiano, Sofian N. Obaid, Zhiyuan Chen, Deji Akinwande, Igor R. Efimov. Advanced Materials Volume 35, Issue 22 June 1, 2023 2212190 DOI: https://doi.org/10.1002/adma.202212190 First published online: 25 March 2023

This paper is open access.

Powered by light: a battery-free pacemaker

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I think it looks more like a potato than a heart but it does illustrate how this new battery-free pacemaker would wrap around a heart,

Caption: An artist’s rendering shows how a new pacemaker, designed by a UArizona-led team of researchers, is able to envelop the heart. The wireless, battery-free pacemaker could be implanted with a less invasive procedure than currently possible and would cause patients less pain. Credit: Philipp Gutruff

An October 27, 2022 news item on ScienceDaily announces a technology that could make life much easier for people with pacemakers (Comment: In the image, that looks more like a potato than a heart, to me),

University of Arizona engineers lead a research team that is developing a new kind of pacemaker, which envelops the heart and uses precise targeting capabilities to bypass pain receptors and reduce patient discomfort.

…

An October 27, 2022 University of Arizona news release (also on EurekAlert) by Emily Dieckman, which originated the news item, explains the reasons for the research and provides some technical details (Note: Links have been removed),

Pacemakers are lifesaving devices that regulate the heartbeats of people with chronic heart diseases like atrial fibrillation and other forms of arrhythmia. However, pacemaker implantation is an invasive procedure, and the lifesaving pacing the devices provide can be extremely painful. Additionally, pacemakers can only be used to treat a few specific types of disease.

In a paper published Wednesday [October 26, 2022] in Science Advances, a University of Arizona-led team of researchers detail the workings of a wireless, battery-free pacemaker they designed that could be implanted with a less invasive procedure than currently possible and would cause patients less pain. The study was helmed by researchers in the Gutruf Lab, led by biomedical engineering assistant professor and Craig M. Berge Faculty Fellow Philipp Gutruf.

Currently available pacemakers work by implanting one or two leads, or points of contact, into the heart with hooks or screws. If the sensors on these leads detect a dangerous irregularity, they send an electrical shock through the heart to reset the beat.

“All of the cells inside the heart get hit at one time, including the pain receptors, and that’s what makes pacing or defibrillation painful,” Gutruf said. “It affects the heart muscle as a whole.”

The device Gutruf’s team has developed, which has not yet been tested in humans, would allow pacemakers to send much more targeted signals using a new digitally manufactured mesh design that encompasses the entire heart. The device uses light and a technique called optogenetics.

Optogenetics modifies cells, usually neurons, sensitive to light, then uses light to affect the behavior of those cells. This technique only targets cardiomyocytes, the cells of the muscle that trigger contraction and make up the beat of the heart. This precision will not only reduce pain for pacemaker patients by bypassing the heart’s pain receptors, it will also allow the pacemaker to respond to different kinds of irregularities in more appropriate ways. For example, during atrial fibrillation, the upper and lower chambers of the heart beat asynchronously, and a pacemaker’s role is to get the two parts back in line.

“Whereas right now, we have to shock the whole heart to do this, these new devices can do much more precise targeting, making defibrillation both more effective and less painful,” said Igor Efimov, professor of biomedical engineering and medicine at Northwestern University, where the devices were lab-tested. “This technology could make life easier for patients all over the world, while also helping scientists and physicians learn more about how to monitor and treat the disease.”

Flexible mesh encompasses the heart

To ensure the light signals can reach many different parts of the heart, the team created a design that involves encompassing the organ, rather than implanting leads that provide limited points of contact.

The new pacemaker model consists of four petallike structures made of thin, flexible film, which contain light sources and a recording electrode. The petals, specially designed to accommodate the way the heart changes shape as it beats, fold up around the sides of the organ to envelop it, like a flower closing up at night.

“Current pacemakers record basically a simple threshold, and they will tell you, ‘This is going into arrhythmia, now shock!'” Gutruf said. “But this device has a computer on board where you can input different algorithms that allow you to pace in a more sophisticated way. It’s made for research.”

Because the system uses light to affect the heart, rather than electrical signals, the device can continue recording information even when the pacemaker needs to defibrillate. In current pacemakers, the electrical signal from the defibrillation can interfere with recording capabilities, leaving physicians with an incomplete picture of cardiac episodes. Additionally, the device does not require a battery, which could save pacemaker patients from needing to replace the battery in their device every five to seven years, as is currently the norm.

Gutruf’s team collaborated with researchers at Northwestern University on the project. While the current version of the device has been successfully demonstrated in animal models, the researchers look forward to furthering their work, which could improve the quality of life for millions of people.

The prototype looks like this,

Caption: The device uses light and a technique called optogenetics, which modifies cells that are sensitive to light, then uses light to affect the behavior of those cells.. Credit: Philipp Gutruff

Here’s a link to and a citation for the paper,

Wireless, fully implantable cardiac stimulation and recording with on-device computation for closed-loop pacing and defibrillation by Jokubas Ausra, Micah Madrid, Rose T. Yin, Jessica Hanna, Suzanne Arnott, Jaclyn A. Brennan, Roberto Peralta, David Clausen, Jakob A. Bakall, Igor R. Efimov, and Philipp Gutruf. Science Advances 26 Oct 2022 Vol 8, Issue 43 DOI: 10.1126/sciadv.abq7469

This paper is open access.

Enhance or weaken memory with stretchy, bioinspired synaptic transistor

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This news is intriguing since they usually want to enhance memory not weaken it. Interestingly, this October 3, 2022 news item on ScienceDaily doesn’t immediately answer why you might want to weaken memory,

Robotics and wearable devices might soon get a little smarter with the addition of a stretchy, wearable synaptic transistor developed by Penn State engineers. The device works like neurons in the brain to send signals to some cells and inhibit others in order to enhance and weaken the devices’ memories.

Led by Cunjiang Yu, Dorothy Quiggle Career Development Associate Professor of Engineering Science and Mechanics and associate professor of biomedical engineering and of materials science and engineering, the team designed the synaptic transistor to be integrated in robots or wearables and use artificial intelligence to optimize functions. The details were published on Sept. 29 [2022] in Nature Electronics.

“Mirroring the human brain, robots and wearable devices using the synaptic transistor can use its artificial neurons to ‘learn’ and adapt their behaviors,” Yu said. “For example, if we burn our hand on a stove, it hurts, and we know to avoid touching it next time. The same results will be possible for devices that use the synaptic transistor, as the artificial intelligence is able to ‘learn’ and adapt to its environment.”

…

A September 29, 2022 Pennsylvania State University (Penn State) news release (also on EurekAlert but published on October 3, 2022) by Mariah Chuprinski, which originated the news item, explains why you might want to weaken memory,

According to Yu, the artificial neurons in the device were designed to perform like neurons in the ventral tegmental area, a tiny segment of the human brain located in the uppermost part of the brain stem. Neurons process and transmit information by releasing neurotransmitters at their synapses, typically located at the neural cell ends. Excitatory neurotransmitters trigger the activity of other neurons and are associated with enhancing memories, while inhibitory neurotransmitters reduce the activity of other neurons and are associated with weakening memories.

“Unlike all other areas of the brain, neurons in the ventral tegmental area are capable of releasing both excitatory and inhibitory neurotransmitters at the same time,” Yu said. “By designing the synaptic transistor to operate with both synaptic behaviors simultaneously, fewer transistors are needed [emphasis mine] compared to conventional integrated electronics technology, which simplifies the system architecture and allows the device to conserve energy.”

To model soft, stretchy biological tissues, the researchers used stretchable bilayer semiconductor materials to fabricate the device, allowing it to stretch and twist while in use, according to Yu. Conventional transistors, on the other hand, are rigid and will break when deformed.

“The transistor is mechanically deformable and functionally reconfigurable, yet still retains its functions when stretched extensively,” Yu said. “It can attach to a robot or wearable device to serve as their outermost skin.”

In addition to Yu, other contributors include Hyunseok Shim and Shubham Patel, Penn State Department of Engineering Science and Mechanics; Yongcao Zhang, the University of Houston Materials Science and Engineering Program; Faheem Ershad, Penn State Department of Biomedical Engineering and University of Houston Department of Biomedical Engineering; Binghao Wang, School of Electronic Science and Engineering, Southeast University [Note: There’s one in Bangladesh, one in China, and there’s a Southeastern University in Florida, US] and Department of Chemistry and the Materials Research Center, Northwestern University; Zhihua Chen, Flexterra Inc.; Tobin J. Marks, Department of Chemistry and the Materials Research Center, Northwestern University; Antonio Facchetti, Flexterra Inc. and Northwestern University’s Department of Chemistry and Materials Research Center.

Here’s a link to and a citation for the paper,

An elastic and reconfigurable synaptic transistor based on a stretchable bilayer semiconductor by Hyunseok Shim, Faheem Ershad, Shubham Patel, Yongcao Zhang, Binghao Wang, Zhihua Chen, Tobin J. Marks, Antonio Facchetti & Cunjiang Yu. Nature Electronics (2022) DOI: DOI: https://doi.org/10.1038/s41928-022-00836-5 Published: 29 September 2022

This paper is behind a paywall.

“The Heart’s Knowledge: Science and Empathy in the Art of Dario Robleto” from Jan. 27 to July 9, 2023 at The Block Museum of Art (Northwestern University, Chicago, Illinois)

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I’m sorry to be late. Thankfully this show extends into July 2023, so, there’s still plenty of time to get to Chicago’s The Block Museum of Art (at Northwestern University) art/science exhibition. I found this on the museum’s exhibition page for “The Heart’s Knowledge: Science and Empathy in the Art of Dario Robleto” show,

What do we owe to the memories of one another’s hearts?

For American artist Dario Robleto (b. 1972), artists and scientists share a common aspiration: to increase the sensitivity of their observations. Throughout the history of scientific invention, instruments like the cardiograph and the telescope have extended the reach of perception from the tiniest stirrings of the human body to the farthest reaches of space. In his prints, sculptures, and video and sound installations, Robleto contemplates the emotional significance of these technologies, bringing us closer to the latent traces of life buried in the scientific record.

The Heart’s Knowledge concentrates on the most recent decade of Robleto’s creative practice, a period of deepening engagement with histories of medicine, biomedical engineering, sound recording, and space exploration. The exhibition organizes the artist’s conceptually ambitious, elegantly wrought artworks as a series of multisensory encounters between art and science.  Each work seeks to attune viewers to the material traces of life at scales ranging from the intimate to the universal, returning always to the question: Does empathy extend beyond the boundaries of time and space?

…

Banner image for “The Heart’s Knowledge: Science and Empathy in the Art of Dario Robleto” exhibition page. Courtesy of The Block Museum of Art (Northwestern University) and artist, Dario Robleto

Here’s more from a January 27, 2023 Northwestern University news release (received via email),

Exhibition searches for meaning at the limits of science and perception

“The Heart’s Knowledge: Science and Empathy in the Art of Dario Robleto” is on view Jan. 27 to July 9 [2023] at The Block Museum of Art

  • Works are informed by dialogue with Northwestern Engineering researchers during five-year residency  
  • Exhibition a tribute to NASA Golden Record creator, ‘whose heart has left the solar system’
  • Opening conversation with the artist will take place at 2 p.m. on [Saturday] Feb. 4 [2023]

American artist Dario Robleto (b. 1972) believes artists and scientists share a common aspiration: to increase the sensitivity of their observations.

From understanding the human body’s pulses and brainwaves to viewing the faintest glimmers of light from the edge of the observable universe, groundbreaking science pushes the limits of perception. Similarly, the perceptive work of artists can extend the boundaries of empathy and understanding.

Since 2018, Robleto served as an artist-at-large at the McCormick School of Engineering. This unique partnership between The Block Museum and McCormick gave the artist an open “hall pass” to learn from, collaborate with and question scientists, engineers and experts from across the University.

Robleto’s five-year residency concludes with the exhibition “The Heart’s Knowledge: Science and Empathy in the Art of Dario Robleto.” Co-presented by The Block Museum and McCormick, the exhibition is on view from Jan. 27 to July 9 [2023] at The Block Museum, 40 Arts Circle Drive on Northwestern’s Evanston campus. [emphasis mine]

A free opening conversation with the artist will take place at 2 p.m. on Saturday, Feb. 4 [2023], in Norris University Center’s McCormick Auditorium, 1999 Campus Drive in Evanston.

About the Exhibition: “The Heart’s Knowledge”

Throughout the history of scientific invention, instruments like the cardiograph and the telescope have extended the reach of perception from the tiniest stirrings of the human body to the farthest reaches of space.

Robleto’s prints, sculptures and video and sound installations contemplate the emotional significance of these technologies, bringing viewers closer to the latent traces of life buried in the scientific record.

“The Heart’s Knowledge” represents a decade of Robleto’s creative practice, from 2012 to 2022, a period marked by a deepening engagement with science, including astronomy, synthetic biology and exobiology, and a widening embrace of new materials and creative forms, from 3D-printed objects to film.

Robleto dedicates the exhibition to Ann Druyan, the creative director of NASA’s Golden Record for the Voyager 1 and 2 projects. The record includes Druyan’s brainwaves and heartbeats, recorded as she reflected on her secret love for famed astronomer and future husband Carl Sagan. The act of sneaking “love on board the Voyager” inspired Robleto to compose a love letter to the only human whose “heart has left the solar system.”

Robleto sees Druyan’s act to include her emotions on the record as the central inspiration of his work. “I consider it the greatest work of subversive, avant-garde art not yet given its due,” Robleto said. “The Golden Record and Ann’s radical act brought us all together to think about what it means to be human — to one another and to unknown beings on other worlds.”

The exhibition organizes the artist’s conceptually ambitious, elegantly wrought artworks as a series of multisensory encounters between art and science. Each asks viewers to seek out the material traces of life in scales ranging from the intimate to the universal, and to question: Does empathy extend beyond the boundaries of time and space?

“Whether he’s addressing the most minute phenomena of the body or the horizons of the known universe, Robleto binds the rigor of scientific inquiry with artistic expression,” said exhibition curator Michael Metzger, The Block’s Pick-Laudati Curator of Media Arts.

“Straining at the bounds of observation, Robleto discovers unity at the limits; the common endeavor of art and science to achieve a form of knowledge that language alone cannot speak,” Metzger said.

The exhibition includes three sections:

“Heartbeats“
Rooted in the artist’s longstanding fascination with the clinical and cultural history of the human heart, “Heartbeats” draws inspiration from 19th-century pioneers of cardiography, whose instruments graphically measured heart activity for the first time, leaving behind poignant records of human subjectivity. In “The First Time, the Heart (A Portrait of Life 1854-1913)” (2017), Robleto transforms early measurements of heartbeats into photolithographs executed on paper hand-sooted with candle flames. For the installation “The Pulse Armed with a Pen (An Unknown History of the Human Heartbeat)” (2014), Robleto collaborated with sound historian Patrick Feaster to digitally resurrect these heartbeats in audio form, giving visitors access to intimate pulses of life recorded before the invention of sound playback.

“Wavelengths“
Robleto has recently embraced digital video to create works that narrate transformational episodes in the recording and study of wave phenomena. “Wavelengths” comprises two hour-long immersive video installations. “The Boundary of Life is Quietly Crossed” (2019) is inspired by NASA’s Voyager Golden Record, a gold-plated phonographic disc launched into space onboard the Voyager I and II space probes in 1977. In “The Aorta of an Archivist” (2020-2021), Robleto investigates three breakthroughs in the history of recording: the first recording of a choral performance made with an Edison wax cylinder, the first heartbeat captured while listening to music and the first effort to transcribe the brain wave activity of a dreaming subject.

“Horizons“
In the final section, “Horizons,” Robleto evokes the spirit of the Hubble telescope and the search for extraterrestrial life, gazing out at the boundaries of the observable universe. Inspired by his time as an artist-in-residence at the SETI Institute (Search for Extraterrestrial Intelligence) and as artistic consultant to the Breakthrough Initiatives, his intricate sculptures, such as “Small Crafts on Sisyphean Seas” (2018), give shape to the speculative search for intelligent life in the universe. Other works like “The Computer of Jupiter” (2019) are framed as “gifts for extraterrestrials” offering an alternative view of the best way to begin a dialogue with alien intelligences.

The Artist-at-Large Program at Northwestern

Lisa Corrin, the Ellen Philips Katz Executive Director of The Block Museum of Art, and Julio M. Ottino, dean of McCormick School of Engineering, envisioned the possibilities of this unconventional partnership between scientist and artist when they launched the artist-at-large initiative together. The work is part of an ongoing Art + Engineering initiative and a part of the whole-brain engineering philosophy at Northwestern Engineering.

“Here, a university’s school of engineering and its art museum come together in the shared belief that transformative innovation can happen at the intersections of usually distinct academic disciplines and modes of creativity and inquiry,” Corrin said. “We had faith that something meaningful would emerge organically if we merely provided structures in which informal interactions might take place.”

“We wanted to model for young engineers the value of embracing uncertainty as part of the journey that leads to innovation and opens pathways within the imagination — as artists do,” Ottino said. “We are grateful to Dario Robleto for accepting our invitation to come to Northwestern and to enter the unknown with us. He has taught us that our shared future resides in our capacity for compassion and for empathy, the ethos at the heart of his work that holds the most promise for those at the forefront of science in the interest of humankind.”

More information about Robleto’s residency can be found in the article “Dario is our Socrates” on the Block Museum website and by viewing the Northwestern Engineering video “Artist-at-Large Program: Dario Robleto.”

Exhibition Events

“The Heart’s Knowledge” will include six months of events and dialogues that will illuminate the intersections in Robleto’s practice. All events are free and open to the public. For current program information, visit The Block Museum website.

Program highlights for February and March include:

Science, Art and the Search for Meaning: Opening Conversation with Dario Robleto
Saturday, Feb. 4 [2023], 2 p.m.
Norris University Center, McCormick Auditorium
1999 Campus Drive

The Block Museum hosts a discussion that reaches across boundaries to examine the shared pursuit that binds artists and scientists. The conversation features artist Dario Robleto; Jennifer Roberts, professor of the humanities at Harvard University; Lucianne Walkowicz, astronomer and co-founder of the JustSpace Alliance; and Michael Metzger, Pick-Laudati Curator of Media Arts and curator of “The Heart’s Knowledge.”

“X: The Man with the X-Ray Eyes” (1963)
Friday, Feb. 10 [2023], 7 p.m.
Block Cinema
40 Arts Circle Drive

A Science on Screen program with Catherine Belling, associate professor of medical education at Northwestern University Feinberg School of Medicine.

“First Man” (2018)
Saturday Feb. 18 [2023], 1 p.m.
Block Cinema
40 Arts Circle Drive

A Science on Screen program featuring history researcher Jordan Bimm of the University of Chicago, who will discuss the military origins of “space medicine.”

Exhibition Conversation: Interstellar Aesthetics and Acts of Translation in Art and Science
Wednesday, Feb. 22 [2023], 6 p.m.
Block Museum

Joining artist Dario Robleto in conversation are Elizabeth Kessler, exhibition publication contributor and a lecturer in American Studies at Stanford University, and Shane Larson, research professor of physics and astronomy and associate director of CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics) at Northwestern.

Gallery Talk: Stillness, Wonder and Gifts for Extraterrestrials
Thursday, Feb. 23 [2023], 12:30 p.m.
Block Museum

Elizabeth Kessler of Stanford University will discuss Robleto’s “gifts for extraterrestrials” series.

Online Conversation: Ann Druyan, The Golden Record and the Memory of Our Hearts
Wednesday, March 8 [2023], 6 p.m. [ET]
Block Cinema

Ann Druyan, creative director for NASA’s Voyager Interstellar Messaging Project and writer and producer of the PBS television series “Cosmos,” joins Robleto and art historian Jennifer Roberts for a conversation about the Golden Record and the heart’s memory.

Exhibition Publication

In conjunction with the exhibition, The Block Museum of Art and the McCormick School of Engineering are proud to announce the publication of “The Heart’s Knowledge: Science and Empathy in the Art of Dario Robleto,” (Artbook, D.A.P., 2023).

The publication is edited by Michael Metzger with contributions by Metzger, Robert M. Brain, Daniel K. L. Chua, Patrick Feaster, Stefan Helmreich, Elizabeth A. Kessler ,Julius B. Lucks, Elizabeth Kathleen Mitchell, Alexander Rehding, Jennifer L. Roberts, Claire Isabel Webb and Dario Robleto.

About Dario Robleto

Dario Robleto was born in San Antonio, Texas, in 1972 and received his BFA from the University of Texas at San Antonio in 1997. He lives and works in Houston, Texas. The artist has had numerous solo exhibitions since 1997, most recently at the Spencer Museum of Art, Lawrence, Kansas (2021); the Radcliffe Institute for Advanced Study at Harvard University (2019); the McNay Museum, San Antonio, Texas (2018); Menil Collection, Houston, Texas (2014); the Baltimore Museum of Art (2014); the New Orleans Museum of Art (2012); and the Museum of Contemporary Art, Denver (2011).

He is currently working on his first book, “Life Signs: The Tender Science of the Pulsewave,” co-authored with art historian Jennifer Roberts, the Elizabeth Cary Agassiz Professor of the Humanities at Harvard (University of Chicago Press).

Exhibition Credits

“The Heart’s Knowledge: Science and Empathy in the Art of Dario Robleto” exhibition is made possible through a partnership with the Robert R. McCormick School of Engineering and Applied Science at Northwestern University. Major support also was provided by the National Endowment for the Arts. Additional support is contributed by the Dorothy J. Speidel Fund; the Bernstein Family Contemporary Art Fund; the Barry and Mary Ann MacLean Fund for Art and Engineering; the Illinois Arts Council Agency; and the Alumnae of Northwestern University. The exhibition publication is made possible in part by the Sandra L. Riggs Publications Fund.

Should you be in the Chicago area and interested in the exhibit, you can find all the information for your visit here.

Implantable living pharmacy

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I stumbled across a very interesting US Defense Advanced Research Projects Agency (DARPA) project (from an August 30, 2021 posting on Northwestern University’s Rivnay Lab [a laboratory for organic bioelectronics] blog),

Our lab has received a cooperative agreement with DARPA to develop a wireless, fully implantable ‘living pharmacy’ device that could help regulate human sleep patterns. The project is through DARPA’s BTO (biotechnology office)’s Advanced Acclimation and Protection Tool for Environmental Readiness (ADAPTER) program, meant to address physical challenges of travel, such as jetlag and fatigue.

The device, called NTRAIN (Normalizing Timing of Rhythms Across Internal Networks of Circadian Clocks), would control the body’s circadian clock, reducing the time it takes for a person to recover from disrupted sleep/wake cycles by as much as half the usual time.

The project spans 5 institutions including Northwestern, Rice University, Carnegie Mellon, University of Minnesota, and Blackrock Neurotech.

…

Prior to the Aug. 30, 2021 posting, Amanda Morris wrote a May 13, 2021 article for Northwestern NOW (university magazine), which provides more details about the project, Note: A link has been removed,

…

The first phase of the highly interdisciplinary program will focus on developing the implant. The second phase, contingent on the first, will validate the device. If that milestone is met, then researchers will test the device in human trials, as part of the third phase. The full funding corresponds to $33 million over four-and-a-half years. 

Nicknamed the “living pharmacy,” the device could be a powerful tool for military personnel, who frequently travel across multiple time zones, and shift workers including first responders, who vacillate between overnight and daytime shifts.

…

Combining synthetic biology with bioelectronics, the team will engineer cells to produce the same peptides that the body makes to regulate sleep cycles, precisely adjusting timing and dose with bioelectronic controls. When the engineered cells are exposed to light, they will generate precisely dosed peptide therapies. 

“This control system allows us to deliver a peptide of interest on demand, directly into the bloodstream,” said Northwestern’s Jonathan Rivnay, principal investigator of the project. “No need to carry drugs, no need to inject therapeutics and — depending on how long we can make the device last — no need to refill the device. It’s like an implantable pharmacy on a chip that never runs out.” 

…

Beyond controlling circadian rhythms, the researchers believe this technology could be modified to release other types of therapies with precise timing and dosing for potentially treating pain and disease. The DARPA program also will help researchers better understand sleep/wake cycles, in general.

“The experiments carried out in these studies will enable new insights into how internal circadian organization is maintained,” said Turek [Fred W. Turek], who co-leads the sleep team with Vitaterna [Martha Hotz Vitaterna]. “These insights will lead to new therapeutic approaches for sleep disorders as well as many other physiological and mental disorders, including those associated with aging where there is often a spontaneous breakdown in temporal organization.” 

…

For those who like to dig even deeper, Dieynaba Young’s June 17, 2021 article for Smithsonian Magazine (GetPocket.com link to article) provides greater context and greater satisfaction, Note: Links have been removed,

In 1926, Fritz Kahn completed Man as Industrial Palace, the preeminent lithograph in his five-volume publication The Life of Man. The illustration shows a human body bustling with tiny factory workers. They cheerily operate a brain filled with switchboards, circuits and manometers. Below their feet, an ingenious network of pipes, chutes and conveyer belts make up the blood circulatory system. The image epitomizes a central motif in Kahn’s oeuvre: the parallel between human physiology and manufacturing, or the human body as a marvel of engineering.

An apparatus in the embryonic stage of development at the time of this writing in June of 2021—the so-called “implantable living pharmacy”—could have easily originated in Kahn’s fervid imagination. The concept is being developed by the Defense Advanced Research Projects Agency (DARPA) in conjunction with several universities, notably Northwestern and Rice. Researchers envision a miniaturized factory, tucked inside a microchip, that will manufacture pharmaceuticals from inside the body. The drugs will then be delivered to precise targets at the command of a mobile application. …

…

The implantable living pharmacy, which is still in the “proof of concept” stage of development, is actually envisioned as two separate devices—a microchip implant and an armband. The implant will contain a layer of living synthetic cells, along with a sensor that measures temperature, a short-range wireless transmitter and a photo detector. The cells are sourced from a human donor and reengineered to perform specific functions. They’ll be mass produced in the lab, and slathered onto a layer of tiny LED lights.

The microchip will be set with a unique identification number and encryption key, then implanted under the skin in an outpatient procedure. The chip will be controlled by a battery-powered hub attached to an armband. That hub will receive signals transmitted from a mobile app.

If a soldier wishes to reset their internal clock, they’ll simply grab their phone, log onto the app and enter their upcoming itinerary—say, a flight departing at 5:30 a.m. from Arlington, Virginia, and arriving 16 hours later at Fort Buckner in Okinawa, Japan. Using short-range wireless communications, the hub will receive the signal and activate the LED lights inside the chip. The lights will shine on the synthetic cells, stimulating them to generate two compounds that are naturally produced in the body. The compounds will be released directly into the bloodstream, heading towards targeted locations, such as a tiny, centrally-located structure in the brain called the suprachiasmatic nucleus (SCN) that serves as master pacemaker of the circadian rhythm. Whatever the target location, the flow of biomolecules will alter the natural clock. When the solider arrives in Okinawa, their body will be perfectly in tune with local time.

The synthetic cells will be kept isolated from the host’s immune system by a membrane constructed of novel biomaterials, allowing only nutrients and oxygen in and only the compounds out. Should anything go wrong, they would swallow a pill that would kill the cells inside the chip only, leaving the rest of their body unaffected.

…

If you have the time, I recommend reading Young’s June 17, 2021 Smithsonian Magazine article (GetPocket.com link to article) in its entirety. Young goes on to discuss, hacking, malware, and ethical/societal issues and more.

There is an animation of Kahn’s original poster in a June 23, 2011 posting on openculture.com (also found on Vimeo; Der Mensch als Industriepalast [Man as Industrial Palace])

Credits: Idea & Animation: Henning M. Lederer / led-r-r.net; Sound-Design: David Indge; and original poster art: Fritz Kahn.

Shaving the ‘hairs’ off nanocrystals for more efficient electronics

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A March 24, 2022 news item on phys.org announced research into nanoscale crystals and how they might be integrated into electronic devices, Note: A link has been removed,

You can carry an entire computer in your pocket today because the technological building blocks have been getting smaller and smaller since the 1950s. But in order to create future generations of electronics—such as more powerful phones, more efficient solar cells, or even quantum computers—scientists will need to come up with entirely new technology at the tiniest scales.

One area of interest is nanocrystals. These tiny crystals can assemble themselves into many configurations, but scientists have had trouble figuring out how to make them talk to each other.  

A new study introduces a breakthrough in making nanocrystals function together electronically. Published March 25 [2022] in Science, the research may open the doors to future devices with new abilities. 

…

A March 25, 2022 University of Chicago news release (also on EurekAlert but published on March 24, 2022), which originated the news item, expands on the possibilities the research makes possible, Note: Links have been removed,

“We call these super atomic building blocks, because they can grant new abilities—for example, letting cameras see in the infrared range,” said University of Chicago Prof. Dmitri Talapin, the corresponding author of the paper. “But until now, it has been very difficult to both assemble them into structures and have them talk to each other. Now for the first time, we don’t have to choose. This is a transformative improvement.”  

In their paper, the scientists lay out design rules which should allow for the creation of many different types of materials, said Josh Portner, a Ph.D. student in chemistry and one of the first authors of the study. 

A tiny problem

Scientists can grow nanocrystals out of many different materials: metals, semiconductors, and magnets will each yield different properties. But the trouble was that whenever they tried to assemble these nanocrystals together into arrays, the new supercrystals would grow with long “hairs” around them. 

These hairs made it difficult for electrons to jump from one nanocrystal to another. Electrons are the messengers of electronic communication; their ability to move easily along is a key part of any electronic device. 

The researchers needed a method to reduce the hairs around each nanocrystal, so they could pack them in more tightly and reduce the gaps in between. “When these gaps are smaller by just a factor of three, the probability for electrons to jump across is about a billion times higher,” said Talapin, the Ernest DeWitt Burton Distinguished Service Professor of Chemistry and Molecular Engineering at UChicago and a senior scientist at Argonne National Laboratory. “It changes very strongly with distance.”

To shave off the hairs, they sought to understand what was going on at the atomic level. For this, they needed the aid of powerful X-rays at the Center for Nanoscale Materials at Argonne and the Stanford Synchrotron Radiation Lightsource at SLAC National Accelerator Laboratory, as well as powerful simulations and models of the chemistry and physics at play. All these allowed them to understand what was happening at the surface—and find the key to harnessing their production.

Part of the process to grow supercrystals is done in solution—that is, in liquid. It turns out that as the crystals grow, they undergo an unusual transformation in which gas, liquid and solid phases all coexist. By precisely controlling the chemistry of that stage, they could create crystals with harder, slimmer exteriors which could be packed in together much more closely. “Understanding their phase behavior was a massive leap forward for us,” said Portner. 

The full range of applications remains unclear, but the scientists can think of multiple areas where the technique could lead. “For example, perhaps each crystal could be a qubit in a quantum computer; coupling qubits into arrays is one of the fundamental challenges of quantum technology right now,” said Talapin. 

Portner is also interested in exploring the unusual intermediate state of matter seen during supercrystal growth: “Triple phase coexistence like this is rare enough that it’s intriguing to think about how to take advantage of this chemistry and build new materials.”

The study included scientists with the University of Chicago, Technische Universität Dresden, Northwestern University, Arizona State University, SLAC, Lawrence Berkeley National Laboratory, and the University of California, Berkeley.

…

Here’s a link to and a citation for the paper,

Self-assembly of nanocrystals into strongly electronically coupled all-inorganic supercrystals by Igor Coropceanu, Eric M. Janke, Joshua Portner, Danny Haubold, Trung Dac Nguyen, Avishek Das, Christian P. N. Tanner, James K. Utterback, Samuel W. Teitelbaum¸ Margaret H. Hudson, Nivedina A. Sarma, Alex M. Hinkle, Christopher J. Tassone, Alexander Eychmüller, David T. Limmer, Monica Olvera de la Cruz, Naomi S. Ginsberg and Dmitri V. Talapin. Science • 24 Mar 2022 • Vol 375, Issue 6587 • pp. 1422-1426 • DOI: 10.1126/science.abm6753

This paper is behind a paywall.

Will you be my friend? Yes, after we activate our ultraminiature, wireless, battery-free, fully implantable devices

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Perhaps I’m the only one who’s disconcerted?

Here’s the research (in text form) as to why we’re watching these scampering, momentary mouse friends, from a May 10, 2021 Northwestern University news release (also on EurekAlert) by Amanda Morris,

Northwestern University researchers are building social bonds with beams of light.

For the first time ever, Northwestern engineers and neurobiologists have wirelessly programmed — and then deprogrammed — mice to socially interact with one another in real time. The advancement is thanks to a first-of-its-kind ultraminiature, wireless, battery-free and fully implantable device that uses light to activate neurons.

This study is the first optogenetics (a method for controlling neurons with light) paper exploring social interactions within groups of animals, which was previously impossible with current technologies.

The research was published May 10 [2021] in the journal Nature Neuroscience.

The thin, flexible, wireless nature of the implant allows the mice to look normal and behave normally in realistic environments, enabling researchers to observe them under natural conditions. Previous research using optogenetics required fiberoptic wires, which restrained mouse movements and caused them to become entangled during social interactions or in complex environments.

“With previous technologies, we were unable to observe multiple animals socially interacting in complex environments because they were tethered,” said Northwestern neurobiologist Yevgenia Kozorovitskiy, who designed the experiment. “The fibers would break or the animals would become entangled. In order to ask more complex questions about animal behavior in realistic environments, we needed this innovative wireless technology. It’s tremendous to get away from the tethers.”

“This paper represents the first time we’ve been able to achieve wireless, battery-free implants for optogenetics with full, independent digital control over multiple devices simultaneously in a given environment,” said Northwestern bioelectronics pioneer John A. Rogers, who led the technology development. “Brain activity in an isolated animal is interesting, but going beyond research on individuals to studies of complex, socially interacting groups is one of the most important and exciting frontiers in neuroscience. We now have the technology to investigate how bonds form and break between individuals in these groups and to examine how social hierarchies arise from these interactions.”

Kozorovitskiy is the Soretta and Henry Shapiro Research Professor of Molecular Biology and associate professor of neurobiology in Northwestern’s Weinberg College of Arts and Sciences. She also is a member of the Chemistry of Life Processes Institute. Rogers is the Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery in the McCormick School of Engineering and Northwestern University Feinberg School of Medicine and the director of the Querrey Simpson Institute for Bioelectronics.

Kozorovitskiy and Rogers led the work with Yonggang Huang, the Jan and Marcia Achenbach Professor in Mechanical Engineering at McCormick, and Zhaoqian Xie, a professor of engineering mechanics at Dalian University of Technology in China. The paper’s co-first authors are Yiyuan Yang, Mingzheng Wu and Abraham Vázquez-Guardado — all at Northwestern.

Promise and problems of optogenetics

Because the human brain is a system of nearly 100 billion intertwined neurons, it’s extremely difficult to probe single — or even groups of — neurons. Introduced in animal models around 2005, optogenetics offers control of specific, genetically targeted neurons in order to probe them in unprecedented detail to study their connectivity or neurotransmitter release. Researchers first modify neurons in living mice to express a modified gene from light-sensitive algae. Then they can use external light to specifically control and monitor brain activity. Because of the genetic engineering involved, the method is not yet approved in humans.

“It sounds like sci-fi, but it’s an incredibly useful technique,” Kozorovitskiy said. “Optogenetics could someday soon be used to fix blindness or reverse paralysis.”

Previous optogenetics studies, however, were limited by the available technology to deliver light. Although researchers could easily probe one animal in isolation, it was challenging to simultaneously control neural activity in flexible patterns within groups of animals interacting socially. Fiberoptic wires typically emerged from an animal’s head, connecting to an external light source. Then a software program could be used to turn the light off and on, while monitoring the animal’s behavior.

“As they move around, the fibers tugged in different ways,” Rogers said. “As expected, these effects changed the animal’s patterns of motion. One, therefore, has to wonder: What behavior are you actually studying? Are you studying natural behaviors or behaviors associated with a physical constraint?”

Wireless control in real time

A world-renowned leader in wireless, wearable technology, Rogers and his team developed a tiny, wireless device that gently rests on the skull’s outer surface but beneath the skin and fur of a small animal. The half-millimeter-thick device connects to a fine, flexible filamentary probe with LEDs on the tip, which extend down into the brain through a tiny cranial defect.

The miniature device leverages near-field communication protocols, the same technology used in smartphones for electronic payments. Researchers wirelessly operate the light in real time with a user interface on a computer. An antenna surrounding the animals’ enclosure delivers power to the wireless device, thereby eliminating the need for a bulky, heavy battery.

Activating social connections

To establish proof of principle for Rogers’ technology, Kozorovitskiy and colleagues designed an experiment to explore an optogenetics approach to remote-control social interactions among pairs or groups of mice.

When mice were physically near one another in an enclosed environment, Kozorovitskiy’s team wirelessly synchronously activated a set of neurons in a brain region related to higher order executive function, causing them to increase the frequency and duration of social interactions. Desynchronizing the stimulation promptly decreased social interactions in the same pair of mice. In a group setting, researchers could bias an arbitrarily chosen pair to interact more than others.

“We didn’t actually think this would work,” Kozorovitskiy said. “To our knowledge, this is the first direct evaluation of a major long-standing hypothesis about neural synchrony in social behavior.”

Here’s a citation and a link to the paper,

Wireless multilateral devices for optogenetic studies of individual and social behaviors by Yiyuan Yang, Mingzheng Wu, Amy J. Wegener, Jose G. Grajales-Reyes, Yujun Deng, Taoyi Wang, Raudel Avila, Justin A. Moreno, Samuel Minkowicz, Vasin Dumrongprechachan, Jungyup Lee, Shuangyang Zhang, Alex A. Legaria, Yuhang Ma, Sunita Mehta, Daniel Franklin, Layne Hartman, Wubin Bai, Mengdi Han, Hangbo Zhao, Wei Lu, Yongjoon Yu, Xing Sheng, Anthony Banks, Xinge Yu, Zoe R. Donaldson, Robert W. Gereau IV, Cameron H. Good, Zhaoqian Xie, Yonggang Huang, Yevgenia Kozorovitskiy and John A. Rogers. Nature Neuroscience (2021)
DOI: https://doi.org/10.1038/s41593-021-00849-x Published 10 May 2021

This paper is behind a paywall.

This latest research seems to be the continuation of research featured here in a July 16, 2019 posting: “Controlling neurons with light: no batteries or wires needed.”

Synaptic transistor better then memristor when it comes to brainlike learning for computers

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An April 30, 2021 news item on Nanowerk announced research from a joint team at Northwestern University (located in Chicago, Illinois, US) and University of Hong Kong of researchers in the field of neuromorphic (brainlike) computing,

Researchers have developed a brain-like computing device that is capable of learning by association.

Similar to how famed physiologist Ivan Pavlov conditioned dogs to associate a bell with food, researchers at Northwestern University and the University of Hong Kong successfully conditioned their circuit to associate light with pressure.

…

The device’s secret lies within its novel organic, electrochemical “synaptic transistors,” which simultaneously process and store information just like the human brain. The researchers demonstrated that the transistor can mimic the short-term and long-term plasticity of synapses in the human brain, building on memories to learn over time.

With its brain-like ability, the novel transistor and circuit could potentially overcome the limitations of traditional computing, including their energy-sapping hardware and limited ability to perform multiple tasks at the same time. The brain-like device also has higher fault tolerance, continuing to operate smoothly even when some components fail.

“Although the modern computer is outstanding, the human brain can easily outperform it in some complex and unstructured tasks, such as pattern recognition, motor control and multisensory integration,” said Northwestern’s Jonathan Rivnay, a senior author of the study. “This is thanks to the plasticity of the synapse, which is the basic building block of the brain’s computational power. These synapses enable the brain to work in a highly parallel, fault tolerant and energy-efficient manner. In our work, we demonstrate an organic, plastic transistor that mimics key functions of a biological synapse.”

Rivnay is an assistant professor of biomedical engineering at Northwestern’s McCormick School of Engineering. He co-led the study with Paddy Chan, an associate professor of mechanical engineering at the University of Hong Kong. Xudong Ji, a postdoctoral researcher in Rivnay’s group, is the paper’s first author.

Caption: By connecting single synaptic transistors into a neuromorphic circuit, researchers demonstrated that their device could simulate associative learning. Credit: Northwestern University

An April 30, 2021 Northwestern University news release (also on EurekAlert), which originated the news item, includes a good explanation about brainlike computing and information about how synaptic transistors work along with some suggestions for future applications,

Conventional, digital computing systems have separate processing and storage units, causing data-intensive tasks to consume large amounts of energy. Inspired by the combined computing and storage process in the human brain, researchers, in recent years, have sought to develop computers that operate more like the human brain, with arrays of devices that function like a network of neurons.

“The way our current computer systems work is that memory and logic are physically separated,” Ji said. “You perform computation and send that information to a memory unit. Then every time you want to retrieve that information, you have to recall it. If we can bring those two separate functions together, we can save space and save on energy costs.”

Currently, the memory resistor, or “memristor,” is the most well-developed technology that can perform combined processing and memory function, but memristors suffer from energy-costly switching and less biocompatibility. These drawbacks led researchers to the synaptic transistor — especially the organic electrochemical synaptic transistor, which operates with low voltages, continuously tunable memory and high compatibility for biological applications. Still, challenges exist.

“Even high-performing organic electrochemical synaptic transistors require the write operation to be decoupled from the read operation,” Rivnay said. “So if you want to retain memory, you have to disconnect it from the write process, which can further complicate integration into circuits or systems.”

How the synaptic transistor works

To overcome these challenges, the Northwestern and University of Hong Kong team optimized a conductive, plastic material within the organic, electrochemical transistor that can trap ions. In the brain, a synapse is a structure through which a neuron can transmit signals to another neuron, using small molecules called neurotransmitters. In the synaptic transistor, ions behave similarly to neurotransmitters, sending signals between terminals to form an artificial synapse. By retaining stored data from trapped ions, the transistor remembers previous activities, developing long-term plasticity.

The researchers demonstrated their device’s synaptic behavior by connecting single synaptic transistors into a neuromorphic circuit to simulate associative learning. They integrated pressure and light sensors into the circuit and trained the circuit to associate the two unrelated physical inputs (pressure and light) with one another.

Perhaps the most famous example of associative learning is Pavlov’s dog, which naturally drooled when it encountered food. After conditioning the dog to associate a bell ring with food, the dog also began drooling when it heard the sound of a bell. For the neuromorphic circuit, the researchers activated a voltage by applying pressure with a finger press. To condition the circuit to associate light with pressure, the researchers first applied pulsed light from an LED lightbulb and then immediately applied pressure. In this scenario, the pressure is the food and the light is the bell. The device’s corresponding sensors detected both inputs.

After one training cycle, the circuit made an initial connection between light and pressure. After five training cycles, the circuit significantly associated light with pressure. Light, alone, was able to trigger a signal, or “unconditioned response.”

Future applications

Because the synaptic circuit is made of soft polymers, like a plastic, it can be readily fabricated on flexible sheets and easily integrated into soft, wearable electronics, smart robotics and implantable devices that directly interface with living tissue and even the brain [emphasis mine].

“While our application is a proof of concept, our proposed circuit can be further extended to include more sensory inputs and integrated with other electronics to enable on-site, low-power computation,” Rivnay said. “Because it is compatible with biological environments, the device can directly interface with living tissue, which is critical for next-generation bioelectronics.”

Here’s a link to and a citation for the paper,

Mimicking associative learning using an ion-trapping non-volatile synaptic organic electrochemical transistor by Xudong Ji, Bryan D. Paulsen, Gary K. K. Chik, Ruiheng Wu, Yuyang Yin, Paddy K. L. Chan & Jonathan Rivnay . Nature Communications volume 12, Article number: 2480 (2021) DOI: https://doi.org/10.1038/s41467-021-22680-5 Published: 30 April 2021

This paper is open access.

“… devices that directly interface with living tissue and even the brain,” would I be the only one thinking about cyborgs?