Tag Archives: Yonggang Huang

Controlling neurons with light: no batteries or wires needed

Caption: Wireless and battery-free implant with advanced control over targeted neuron groups. Credit: Philipp Gutruf

This January 2, 2019 news item on ScienceDaily describes the object seen in the above and describes the problem it’s designed to solve,

University of Arizona biomedical engineering professor Philipp Gutruf is first author on the paper Fully implantable, optoelectronic systems for battery-free, multimodal operation in neuroscience research, published in Nature Electronics.

Optogenetics is a biological technique that uses light to turn specific neuron groups in the brain on or off. For example, researchers might use optogenetic stimulation to restore movement in case of paralysis or, in the future, to turn off the areas of the brain or spine that cause pain, eliminating the need for — and the increasing dependence on — opioids and other painkillers.

“We’re making these tools to understand how different parts of the brain work,” Gutruf said. “The advantage with optogenetics is that you have cell specificity: You can target specific groups of neurons and investigate their function and relation in the context of the whole brain.”

In optogenetics, researchers load specific neurons with proteins called opsins, which convert light to electrical potentials that make up the function of a neuron. When a researcher shines light on an area of the brain, it activates only the opsin-loaded neurons.

The first iterations of optogenetics involved sending light to the brain through optical fibers, which meant that test subjects were physically tethered to a control station. Researchers went on to develop a battery-free technique using wireless electronics, which meant subjects could move freely.

But these devices still came with their own limitations — they were bulky and often attached visibly outside the skull, they didn’t allow for precise control of the light’s frequency or intensity, and they could only stimulate one area of the brain at a time.

A Dec. 21, 2018 University of Azrizona news release (published Jan. 2, 2019 on EurekAlert), which originated the news item, discusses the work in more detail,

“With this research, we went two to three steps further,” Gutruf said. “We were able to implement digital control over intensity and frequency of the light being emitted, and the devices are very miniaturized, so they can be implanted under the scalp. We can also independently stimulate multiple places in the brain of the same subject, which also wasn’t possible before.”

The ability to control the light’s intensity is critical because it allows researchers to control exactly how much of the brain the light is affecting — the brighter the light, the farther it will reach. In addition, controlling the light’s intensity means controlling the heat generated by the light sources, and avoiding the accidental activation of neurons that are activated by heat.

The wireless, battery-free implants are powered by external oscillating magnetic fields, and, despite their advanced capabilities, are not significantly larger or heavier than past versions. In addition, a new antenna design has eliminated a problem faced by past versions of optogenetic devices, in which the strength of the signal being transmitted to the device varied depending on the angle of the brain: A subject would turn its head and the signal would weaken.

“This system has two antennas in one enclosure, which we switch the signal back and forth very rapidly so we can power the implant at any orientation,” Gutruf said. “In the future, this technique could provide battery-free implants that provide uninterrupted stimulation without the need to remove or replace the device, resulting in less invasive procedures than current pacemaker or stimulation techniques.”

Devices are implanted with a simple surgical procedure similar to surgeries in which humans are fitted with neurostimulators, or “brain pacemakers.” They cause no adverse effects to subjects, and their functionality doesn’t degrade in the body over time. This could have implications for medical devices like pacemakers, which currently need to be replaced every five to 15 years.

The paper also demonstrated that animals implanted with these devices can be safely imaged with computer tomography, or CT, and magnetic resonance imaging, or MRI, which allow for advanced insights into clinically relevant parameters such as the state of bone and tissue and the placement of the device.

This image of a combined MRI (magnetic resonance image) and CT (computer tomography) scan bookends, more or less, the picture of the device which headed this piece,

Combined image analysis with MRI and CT results superimposed on a 3D rendering of the animal implanted with the programmable bilateral multi µ-ILED device. Courtesy: University of Arizona

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

Fully implantable optoelectronic systems for battery-free, multimodal operation in neuroscience research by Philipp Gutruf, Vaishnavi Krishnamurthi, Abraham Vázquez-Guardado, Zhaoqian Xie, Anthony Banks, Chun-Ju Su, Yeshou Xu, Chad R. Haney, Emily A. Waters, Irawati Kandela, Siddharth R. Krishnan, Tyler Ray, John P. Leshock, Yonggang Huang, Debashis Chanda, & John A. Rogers. Nature Electronics volume 1, pages652–660 (2018) DOI: https://doi.org/10.1038/s41928-018-0175-0 Published 13 December 2018

This paper is behind a paywall.

On the verge of controlling neurons by wireless?

Scientists have controlled a mouse’s neurons with a wireless device (and unleashed some paranoid fantasies? well, mine if no one else’s) according to a July 16, 2015 news item on Nanowerk (Note: A link has been removed),

A study showed that scientists can wirelessly determine the path a mouse walks with a press of a button. Researchers at the Washington University School of Medicine, St. Louis, and University of Illinois, Urbana-Champaign, created a remote controlled, next-generation tissue implant that allows neuroscientists to inject drugs and shine lights on neurons deep inside the brains of mice. The revolutionary device is described online in the journal Cell (“Wireless Optofluidic Systems for Programmable In Vivo Pharmacology and Optogenetics”). Its development was partially funded by the [US] National Institutes of Health [NIH].

The researchers have made an image/illustration of the probe available,

Mind Bending Probe Scientists used soft materials to create a brain implant a tenth the width of a human hair that can wirelessly control neurons with lights and drugs. Courtesy of Jeong lab, University of Colorado Boulder.

A July 16, 2015 US NIH National Institute of Neurological Disorders and Stroke news release, which originated the news item, describes the study and notes that instructions for building the implant are included in the published study,

“It unplugs a world of possibilities for scientists to learn how brain circuits work in a more natural setting.” said Michael R. Bruchas, Ph.D., associate professor of anesthesiology and neurobiology at Washington University School of Medicine and a senior author of the study.

The Bruchas lab studies circuits that control a variety of disorders including stress, depression, addiction, and pain. Typically, scientists who study these circuits have to choose between injecting drugs through bulky metal tubes and delivering lights through fiber optic cables. Both options require surgery that can damage parts of the brain and introduce experimental conditions that hinder animals’ natural movements.

To address these issues, Jae-Woong Jeong, Ph.D., a bioengineer formerly at the University of Illinois at Urbana-Champaign, worked with Jordan G. McCall, Ph.D., a graduate student in the Bruchas lab, to construct a remote controlled, optofluidic implant. The device is made out of soft materials that are a tenth the diameter of a human hair and can simultaneously deliver drugs and lights.

“We used powerful nano-manufacturing strategies to fabricate an implant that lets us penetrate deep inside the brain with minimal damage,” said John A. Rogers, Ph.D., professor of materials science and engineering, University of Illinois at Urbana-Champaign and a senior author. “Ultra-miniaturized devices like this have tremendous potential for science and medicine.”

With a thickness of 80 micrometers and a width of 500 micrometers, the optofluidic implant is thinner than the metal tubes, or cannulas, scientists typically use to inject drugs. When the scientists compared the implant with a typical cannula they found that the implant damaged and displaced much less brain tissue.

The scientists tested the device’s drug delivery potential by surgically placing it into the brains of mice. In some experiments, they showed that they could precisely map circuits by using the implant to inject viruses that label cells with genetic dyes. In other experiments, they made mice walk in circles by injecting a drug that mimics morphine into the ventral tegmental area (VTA), a region that controls motivation and addiction.

The researchers also tested the device’s combined light and drug delivery potential when they made mice that have light-sensitive VTA neurons stay on one side of a cage by commanding the implant to shine laser pulses on the cells. The mice lost the preference when the scientists directed the device to simultaneously inject a drug that blocks neuronal communication. In all of the experiments, the mice were about three feet away from the command antenna.

“This is the kind of revolutionary tool development that neuroscientists need to map out brain circuit activity,” said James Gnadt, Ph.D., program director at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS).  “It’s in line with the goals of the NIH’s BRAIN Initiative.”

The researchers fabricated the implant using semi-conductor computer chip manufacturing techniques. It has room for up to four drugs and has four microscale inorganic light-emitting diodes. They installed an expandable material at the bottom of the drug reservoirs to control delivery. When the temperature on an electric heater beneath the reservoir rose then the bottom rapidly expanded and pushed the drug out into the brain.

“We tried at least 30 different prototypes before one finally worked,” said Dr. McCall.

“This was truly an interdisciplinary effort,” said Dr. Jeong, who is now an assistant professor of electrical, computer, and energy engineering at University of Colorado Boulder. “We tried to engineer the implant to meet some of neurosciences greatest unmet needs.”

In the study, the scientists provide detailed instructions for manufacturing the implant.

“A tool is only good if it’s used,” said Dr. Bruchas. “We believe an open, crowdsourcing approach to neuroscience is a great way to understand normal and healthy brain circuitry.”

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

Wireless Optofluidic Systems for Programmable In Vivo Pharmacology and Optogenetics by Jae-Woong Jeong, Jordan G. McCall, Gunchul Shin, Yihui Zhang, Ream Al-Hasani, Minku Kim, Shuo Li, Joo Yong Sim, Kyung-In Jang, Yan Shi, Daniel Y. Hong, Yuhao Liu, Gavin P. Schmitz, Li Xia, Zhubin He, Paul Gamble, Wilson Z. Ray, Yonggang Huang, Michael R. Bruchas, and John A. Rogers.  Cell, July 16, 2015. DOI: 10.1016/j.cell.2015.06.058

This paper is behind a paywall.

I last wrote about wireless activation of neurons in a May 28, 2014 posting which featured research at the University of Massachusetts Medical School.

E-tattoo without the nanotech

John Rogers and his team at the University of Illinois and a colleague’s (Yonggang Huang) team at Northwestern University have devised an ‘electronic tattoo’ (a soft, stick-on patch) made up from materials that anyone can purchase off-the-shelf. Rogers is known for his work with nanomaterials (my Aug. 10, 2012 posting titled ‘Surgery with fingertip control‘ mentioned a silicon nanomembrane that can be fitted onto the fingertips for possible use in surgical procedures) and with electronics (my Aug. 12, 2011 posting titled: ‘Electronic tattoos‘ mentioned his earlier attempts at developing e-tattoos).

This latest effort from Rogers and his multi-university team is mentioned in an April 4, 2014 article by Mark Wilson for Fast Company,

About a year ago, University of Illinois researcher John Rogers revealed a pretty amazing creation: a circuit that, rather than living on an inflexible board, could stick to and move with someone’s skin just like an ink stamp. But like any early research, it was mostly a proof-of-concept, and it would require relatively expensive, custom-printed electronics to work.

Today, Rogers, in conjunction with Northwestern University’s Yonggang Huang, has published details on version 2.0 in Science, revealing that this once-esoteric project has more immediate, mass market appeal.

… It means that you could create a wearable electronic that’s one-part special sticky circuit board, every other part whatever-the-hell-you-manufactured-in-China. This flexible circuit could accommodate a stock battery, an accelerometer, a Wi-Fi chip, and a Bluetooth circuitry, for instance, all living on your skin rather than inside your iPhone. And as an added bonus, it would be relatively cheap.

A University of Illinois April ?, 2014 news release describes Rogers, his multi-university team, and their current (pun intended) e-tattoo,

Engineers at the University of Illinois at Urbana-Champaign and Northwestern University have demonstrated thin, soft stick-on patches that stretch and move with the skin and incorporate commercial, off-the-shelf chip-based electronics for sophisticated wireless health monitoring.

The patches stick to the skin like a temporary tattoo and incorporate a unique microfluidic construction with wires folded like origami to allow the patch to bend and flex without being constrained by the rigid electronics components. The patches could be used for everyday health tracking – wirelessly sending updates to your cellphone or computer – and could revolutionize clinical monitoring such as EKG and EEG testing – no bulky wires, pads or tape needed.

“We designed this device to monitor human health 24/7, but without interfering with a person’s daily activity,” said Yonggang Huang, the Northwestern University professor who co-led the work with Illinois professor John A. Rogers. “It is as soft as human skin and can move with your body, but at the same time it has many different monitoring functions. What is very important about this device is it is wirelessly powered and can send high-quality data about the human body to a computer, in real time.”

The researchers did a side-by-side comparison with traditional EKG and EEG monitors and found the wireless patch performed equally to conventional sensors, while being significantly more comfortable for patients. Such a distinction is crucial for long-term monitoring, situations such as stress tests or sleep studies when the outcome depends on the patient’s ability to move and behave naturally, or for patients with fragile skin such as premature newborns.

Rogers’ group at Illinois previously demonstrated skin electronics made of very tiny, ultrathin, specially designed and printed components. While those also offer high-performance monitoring, the ability to incorporate readily available chip-based components provides many important, complementary capabilities in engineering design, at very low cost.

“Our original epidermal devices exploited specialized device geometries – super thin, structured in certain ways,” Rogers said. “But chip-scale devices, batteries, capacitors and other components must be re-formulated for these platforms. There’s a lot of value in complementing this specialized strategy with our new concepts in microfluidics and origami interconnects to enable compatibility with commercial off-the-shelf parts for accelerated development, reduced costs and expanded options in device types.”

The multi-university team turned to soft microfluidic designs to address the challenge of integrating relatively big, bulky chips with the soft, elastic base of the patch. The patch is constructed of a thin elastic envelope filled with fluid. The chip components are suspended on tiny raised support points, bonding them to the underlying patch but allowing the patch to stretch and move.

One of the biggest engineering feats of the patch is the design of the tiny, squiggly wires connecting the electronics components – radios, power inductors, sensors and more. The serpentine-shaped wires are folded like origami, so that no matter which way the patch bends, twists or stretches, the wires can unfold in any direction to accommodate the motion. Since the wires stretch, the chips don’t have to.

Skin-mounted devices could give those interested in fitness tracking a more complete and accurate picture of their activity level.

“When you measure motion on a wristwatch type device, your body is not very accurately or reliably coupled to the device,” said Rogers, a Swanlund Professor of Materials Science and Engineering at the U. of I. “Relative motion causes a lot of background noise. If you have these skin-mounted devices and an ability to locate them on multiple parts of the body, you can get a much deeper and richer set of information than would be possible with devices that are not well coupled with the skin. And that’s just the beginning of the rich range of accurate measurements relevant to physiological health that are possible when you are softly and intimately integrated onto the skin.”

The researchers hope that their sophisticated, integrated sensing systems could not only monitor health but also could help identify problems before the patient may be aware. For example, according to Rogers, data analysis could detect motions associated with Parkinson’s disease at its onset.

“The application of stretchable electronics to medicine has a lot of potential,” Huang said. “If we can continuously monitor our health with a comfortable, small device that attaches to our skin, it could be possible to catch health conditions before experiencing pain, discomfort and illness.”

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

Soft Microfluidic Assemblies of Sensors, Circuits, and Radios for the Skin by Sheng Xu, Yihui Zhang, Lin Jia, Kyle E. Mathewson, Kyung-In Jang, Jeonghyun Kim, Haoran Fu, Xian Huang, Pranav Chava, Renhan Wang, Sanat Bhole, Lizhe Wang, Yoon Joo Na, Yue Guan, Matthew Flavin, Zheshen Han, Yonggang Huang, & John A. Rogers. Science 4 April 2014: Vol. 344 no. 6179 pp. 70-74 DOI: 10.1126/science.1250169

This paper is behind a paywall.

Seeing things from a bug’s perspective—a new type of digital camera

The new digital cameras exploit large arrays of tiny focusing lenses and miniaturized detectors in hemispherical layouts, just like eyes found in arthropods

The new digital cameras exploit large arrays of tiny focusing lenses and miniaturized detectors in hemispherical layouts, just like eyes found in arthropods

A May 1, 2013 news item on Nanowerk provides some details about a new ‘bug-eyed’ digital camera,

An interdisciplinary team of researchers has created the first digital cameras with designs that mimic those of ocular systems found in dragonflies, bees, praying mantises and other insects. This class of technology offers exceptionally wide-angle fields of view, with low aberrations, high acuity to motion, and nearly infinite depth of field.

Taking cues from Mother Nature, the cameras exploit large arrays of tiny focusing lenses and miniaturized detectors in hemispherical layouts, just like eyes found in arthropods. The devices combine soft, rubbery optics with high performance silicon electronics and detectors, using ideas first established in research on skin and brain monitoring systems by John A. Rogers, a Swanlund Chair Professor at the University of Illinois at Urbana-Champaign, and his collaborators.

The May 1, 2013 University of Illinois news release by John Kubetz, which originated the news item, describes the special properties of an insect eye and how the camera mimics those properties,

Eyes in arthropods use compound designs, in which arrays of smaller eyes act together to provide image perception. Each small eye, known as an ommatidium, consists of a corneal lens, a crystalline cone, and a light sensitive organ at the base. The entire system is configured to provide exceptional properties in imaging, many of which lie beyond the reach of existing man-made cameras.

The researchers developed new ideas in materials and fabrication strategies allowing construction of artificial ommatidia in large, interconnected arrays in hemispherical layouts. Building such systems represents a daunting task, as all established camera technologies rely on bulk glass lenses and detectors constructed on the planar surfaces of silicon wafers which cannot be bent or flexed, much less formed into a hemispherical shape.

“A critical feature of our fly’s eye cameras is that they incorporate integrated microlenses, photodetectors, and electronics on hemispherically curved surfaces,” said Jianliang Xiao, an assistant professor of mechanical engineering at University of Colorado Boulder and coauthor of the study. “To realize this outcome, we used soft, rubbery optics bonded to detectors/electronics in mesh layouts that can be stretched and deformed, reversibly and without damage.”

On a more technical note, from the news release,

The fabrication starts with electronics, detectors and lens arrays formed on flat surfaces using advanced techniques adapted from the semiconductor industry, said Xiao [Jianliang Xiao, an assistant professor of mechanical engineering at University of Colorado Boulder and coauthor of the study], who began working on the project as a postdoctoral researcher in Rogers’ lab at Illinois. The lens sheet—made from a polymer material similar to a contact lens—and the electronics/detectors are then aligned and bonded together. Pneumatic pressure deforms the resulting system into the desired hemispherical shape, in a process much like blowing up a balloon, but with precision engineering control.

The individual electronic detectors and microlenses are coupled together to avoid any relative motion during this deformation process. Here, the spaces between these artificial ommatidia can stretch to allow transformation in geometry from planar to hemispherical. The electrical interconnections are thin, and narrow, in filamentary serpentine shapes; they deform as tiny springs during the stretching process.

According to the researchers, each microlens produces a small image of an object with a form dictated by the parameters of the lens and the viewing angle. An individual detector responds only if a portion of the image formed by the associated microlens overlaps the active area. The detectors stimulated in this way produce a sampled image of the object that can then be reconstructed using models of the optics.

Katherine Bourzac in her May 1, 2013 article for Nature magazine provides some additional insight and a perspective (intentional wordplay) from a researcher who has an idea of how he might like to integrate this new type of camera into his own work,

Insect eyes are made up of hundreds or even thousands of light-sensing structures called ommatidia. Each contains a lens and a cone that funnels light to a photosensitive organ. The long, thin ommatidia are bunched together to form the hemispherical eye, with each ommatidium pointing in a slightly different direction. This structure gives bugs a wide field of view, with objects in the periphery just as clear as those in the centre of the visual field, and high motion sensitivity. It also allows a large depth of field — objects are in focus whether they’re nearby or at a distance.

“The whole thing [the new digital camera] is stretchy and thin, and we blow it up like a balloon” so that it curves like a compound eye, says Rogers. The current prototype produces black-and-white images only, but Rogers says a colour version could be made with the same design.

With the basic designs in place, Rogers says, his team can now increase the resolution of the camera by incorporating more ommatidia. “We’d like to do a dragonfly, with 20,000 ommatidia,” he says, which will require some miniaturization of the components.

Alexander Borst, who builds miniature flying robots at the Max Planck Institute of Neurobiology in Martinsried, Germany, says that he is eager to integrate the camera into his machines. Insects’ wide field of vision helps them to monitor and stabilize their position during flight; robots with artificial compound eyes might be better fliers, he says.

For interested parties, here’s a link to and a citation for the research paper,

Digital cameras with designs inspired by the arthropod eye by Young Min Song, Yizhu Xie, Viktor Malyarchuk, Jianliang Xiao, Inhwa Jung, Ki-Joong Choi, Zhuangjian Liu, Hyunsung Park, Chaofeng Lu, Rak-Hwan Kim, Rui Li, Kenneth B. Crozier, Yonggang Huang, & John A. Rogers.
Nature 497, 95–99 (02 May 2013) doi:10.1038/nature12083 Published online 01 May 2013

This article is behind a paywall.

I last mentioned John A. Rogers and the University of Illinois in a Feb. 28, 2013 posting about a bendable, stretchable lithium-ion battery.

Bend it, twist it, any way you want to—a foldable lithium-ion battery

Feb. 26, 2013 news item on ScienceDaily features an extraordinary lithium-ion battery,

Northwestern University’s Yonggang Huang and the University of Illinois’ John A. Rogers are the first to demonstrate a stretchable lithium-ion battery — a flexible device capable of powering their innovative stretchable electronics.

No longer needing to be connected by a cord to an electrical outlet, the stretchable electronic devices now could be used anywhere, including inside the human body. The implantable electronics could monitor anything from brain waves to heart activity, succeeding where flat, rigid batteries would fail.

Huang and Rogers have demonstrated a battery that continues to work — powering a commercial light-emitting diode (LED) — even when stretched, folded, twisted and mounted on a human elbow. The battery can work for eight to nine hours before it needs recharging, which can be done wirelessly.

The researchers at Northwestern have produced a video where they demonstrate the battery’s ‘stretchability’,

The Northwestern University Feb. 26, 2013 news release by Megan Fellman, which originated the news item, offers this detail,

“We start with a lot of battery components side by side in a very small space, and we connect them with tightly packed, long wavy lines,” said Huang, a corresponding author of the paper. “These wires provide the flexibility. When we stretch the battery, the wavy interconnecting lines unfurl, much like yarn unspooling. And we can stretch the device a great deal and still have a working battery.”

The power and voltage of the stretchable battery are similar to a conventional lithium-ion battery of the same size, but the flexible battery can stretch up to 300 percent of its original size and still function.

Huang and Rogers have been working together for the last six years on stretchable electronics, and designing a cordless power supply has been a major challenge. Now they have solved the problem with their clever “space filling technique,” which delivers a small, high-powered battery.

For their stretchable electronic circuits, the two developed “pop-up” technology that allows circuits to bend, stretch and twist. They created an array of tiny circuit elements connected by metal wire “pop-up bridges.” When the array is stretched, the wires — not the rigid circuits — pop up.

This approach works for circuits but not for a stretchable battery. A lot of space is needed in between components for the “pop-up” interconnect to work. Circuits can be spaced out enough in an array, but battery components must be packed tightly to produce a powerful but small battery. There is not enough space between battery components for the “pop-up” technology to work.

Huang’s design solution is to use metal wire interconnects that are long, wavy lines, filling the small space between battery components. (The power travels through the interconnects.)

The unique mechanism is a “spring within a spring”: The line connecting the components is a large “S” shape and within that “S” are many smaller “S’s.” When the battery is stretched, the large “S” first stretches out and disappears, leaving a line of small squiggles. The stretching continues, with the small squiggles disappearing as the interconnect between electrodes becomes taut.

“We call this ordered unraveling,” Huang said. “And this is how we can produce a battery that stretches up to 300 percent of its original size.”

The stretching process is reversible, and the battery can be recharged wirelessly. The battery’s design allows for the integration of stretchable, inductive coils to enable charging through an external source but without the need for a physical connection.

Huang, Rogers and their teams found the battery capable of 20 cycles of recharging with little loss in capacity. The system they report in the paper consists of a square array of 100 electrode disks, electrically connected in parallel.

I’d like to see this battery actually powering a device even though the stretching is quite alluring in its way. For those who are interested here’s a citation and a link to the research paper,

Stretchable batteries with self-similar serpentine interconnects and integrated wireless recharging systems by Sheng Xu, Yihui Zhang, Jiung Cho, Juhwan Lee, Xian Huang, Lin Jia, Jonathan A. Fan, Yewang Su, Jessica Su, Huigang Zhang, Huanyu Cheng, Bingwei Lu,           Cunjiang Yu, Chi Chuang, Tae-il Kim, Taeseup Song, Kazuyo Shigeta, Sen Kang, Canan Dagdeviren, Ivan Petrov  et al.   Nature Communications 4, Article number: 1543 doi: 10.1038/ncomms2553  Published 26 February 2013

The article is behind a paywall.

Surgery with fingertip control

In the future, ‘surgery at your fingertips’ could be literally true. Researchers at the University of Illinois at Urbana-Champaign have created a silicon nanomembrane that can be fitted onto the fingertips and could, one day, be used in surgical procedures. From the Aug. 9, 2012 news item on ScienceDaily,

The intricate properties of the fingertips have been mimicked and recreated using semiconductor devices in what researchers hope will lead to the development of advanced surgical gloves.

The devices, shown to be capable of responding with high precision to the stresses and strains associated with touch and finger movement, are a step towards the creation of surgical gloves for use in medical procedures such as local ablations [excising or removing tissue] and ultrasound scans.

Researchers from the University of Illinois at Urbana-Champaign, Northwestern University and Dalian University of Technology have published their study August 10, in IOP [Institute of Physics] Publishing’s journal Nanotechnology.

The Aug. 10,2012 posting on the IOP website  offers this detail about the research,

The electronic circuit on the ‘skin’ is made of patterns of gold conductive lines and ultrathin sheets of silicon, integrated onto a flexible polymer called polyimide. The sheet is then etched into an open mesh geometry and transferred to a thin sheet of silicone rubber moulded into the precise shape of a finger.

This electronic ‘skin’, or finger cuff, was designed to measure the stresses and strains at the fingertip by measuring the change in capacitance – the ability to store electrical charge – of pairs of microelectrodes in the circuit.  Applied forces decreased the spacing in the skin which, in turn, increased the capacitance.

The fingertip device could also be fitted with sensors for measuring motion and temperature, with small-scale heaters as actuators for ablation and other related operations

The researchers experimented with having the electronics on the inside of the device, in contact with wearer’s skin, and also on the outside. They believe that because the device exploits materials and fabrication techniques adopted from the established semiconductor industry, the processes can be scaled for realistic use at reasonable cost.

“Perhaps the most important result is that we are able to incorporate multifunctional, silicon semiconductor device technologies into the form of soft, three-dimensional, form-fitting skins, suitable for integration not only with the fingertips but also other parts of the body,” continued Professor Rogers [John Rogers, co-author of the study].

Here’s what an image of these e-fingertips,

Virtual touch. Electronic fingertips could one day allow us to feel virtual sensations. Credit: John Rogers/University of Illinois at Urbana-Champaign

Krystnell A offers a more detailed description of the e-fingetips in an Aug. 9, 2012 story for Science NOW,

Hoping to create circuits with the flexibility of skin, materials scientist John Rogers of the University of Illinois, Urbana-Champaign, and colleagues cut up nanometer-sized strips of silicon; implanted thin, wavy strips of gold to conduct electricity; and mounted the entire circuit in a stretchable, spider web-type mesh of polymer as a support. They then embedded the circuit-polyimide structure onto a hollow tube of silicone that had been fashioned in the shape of a finger. Just like turning a sock inside out, the researchers flipped the structure so that the circuit, which was once on the outside of the tube, was on the inside where it could touch a finger placed against it.

To test the electronic fingers, the researchers put them on and pressed flat objects, such as the top of their desks. The pressure created electric currents that were transferred to the skin, which the researchers felt as mild tingling. That’s a first step in creating electrical signals that could be sent to the fingers, which could virtually recreate sensations such as heat, pressure, and texture, the team reports online today in Nanotechnology.

Rogers says another application of the technology is to custom fit the “electronic skin” around entire organs, allowing doctors to remotely monitor changes in temperature and blood flow. Electronic skin could also restore sensation to people who have lost their natural skin, he says, such as burn victims or amputees.

Here’s a link to the article which is freely accessible for 30 days after publication, from the Aug. 9, 2012 news item on ScienceDaily,

Ming Ying, Andrew P Bonifas, Nanshu Lu, Yewang Su, Rui Li, Huanyu Cheng, Abid Ameen, Yonggang Huang, John A Rogers. Silicon nanomembranes for fingertip electronics. Nanotechnology, 2012; 23 (34): 344004 DOI: 10.1088/0957-4484/23/34/344004

My best guess is that free access will no longer be available by Sept. 7 (or so) , 2012. I last wrote about John Rogers’ work in an Aug. 12, 2011 posting about electronic tattoos.

Electronic tattoos

Yes, you can temporarily apply electronics that look like tattoos to your skin. From the August 11, 2011 news item on physorg.com,

Engineers have developed a device platform that combines electronic components for sensing, medical diagnostics, communications and human-machine interfaces, all on an ultrathin skin-like patch that mounts directly onto the skin with the ease, flexibility and comfort of a temporary tattoo.

The team led by professor John Rogers at the University of Illinois has create wearable electronics.

The patches are initially mounted on a thin sheet of water-soluble plastic, then laminated to the skin with water – just like applying a temporary tattoo. Alternately, the electronic components can be applied directly to a temporary tattoo itself, providing concealment for the electronics.

Here’s a video released by the University of Illinois featuring Rogers and his colleague, lead author Dae-Hyeong Kim, describing their work,
http://www.youtube.com/watch?v=tOk7OWZ-Lck

(ETA April 7, 2014: This link leads to a notice that the video is no long available.)

Possible applications for this technology include (from the news item on physorg.com),

In addition to gathering data, skin-mounted electronics could provide the wearers with added capabilities. For example, patients with muscular or neurological disorders, such as ALS, could use them to communicate or to interface with computers. The researchers found that, when applied to the skin of the throat, the sensors could distinguish muscle movement for simple speech. The researchers have even used the electronic patches to control a video game, demonstrating the potential for human-computer interfacing.

The August 11, 2011 news item about this research on Nanwerk features some technical details [Note: The news item on physorg.com also offers technical information but the Nanowerk item from the National Science Foundation offered some additional details.],

The researchers have created a new class of micro-electronics with a technology that they call an epidermal electronic system (EES). They have incorporated miniature sensors, light-emitting diodes, tiny transmitters and receivers, and networks of carefully crafted wire filaments into their initial designs.

The technology is presented—along with initial measurements that researchers captured using the EES—in a paper by lead author Dae-Hyeong Kim of the University of Illinois and colleagues in the August 12, 2011, issue of Science (“Epidermal Electronics “).

While existing technologies accurately measure heart rate, brain waves and muscle activity, EES devices offer the opportunity to seamlessly apply sensors that have almost no weight, no external wires and require negligible power.

Because of the small power requirements, the devices can draw power from stray (or transmitted) electromagnetic radiation through the process of induction and can harvest a portion of their energy requirements from miniature solar collectors.

The EES designs yield flat devices that are less than 50-microns thick—thinner than the diameter of a human hair—which are integrated onto the polyester backing familiar from stick-on tattoos.

The devices are so thin that close-contact forces called van der Waals interactions dominate the adhesion at the molecular level, so the electronic tattoos adhere to the skin without any glues and stay in place for hours. The recent study demonstrated device lifetimes of up to 24 hours under ideal conditions.

In light of today’s earlier posting on surveillance, I’m torn between appreciating the technological advance with its attendant possibilities and my concerns over increased monitoring.

Adding to my disconcertment is this comment from one of Rogers’ other colleagues (from the news item on physorg.com),

“The blurring of electronics and biology is really the key point here,” Huang [Northwestern University engineering professor Yonggang Huang] said. “All established forms of electronics are hard, rigid. Biology is soft, elastic. It’s two different worlds. This is a way to truly integrate them.”

Engineers never talk about the social implications of these concepts (integrating biology and electronics) which can be quite frightening and upsetting to some folks depending on how they are introduced to the concept.

While existing technologies accurately measure heart rate, brain waves and muscle activity, EES devices offer the opportunity to seamlessly apply sensors that have almost no weight, no external wires and require negligible power.
Because of the small power requirements, the devices can draw power from stray (or transmitted) electromagnetic radiation through the process of induction and can harvest a portion of their energy requirements from miniature solar collectors.
The EES designs yield flat devices that are less than 50-microns thick—thinner than the diameter of a human hair—which are integrated onto the polyester backing familiar from stick-on tattoos.
The devices are so thin that close-contact forces called van der Waals interactions dominate the adhesion at the molecular level, so the electronic tattoos adhere to the skin without any glues and stay in place for hours. The recent study demonstrated device lifetimes of up to 24 hours under ideal conditions.