Tag Archives: Purdue University

Organismic learning—learning to forget

This approach to mimicking the human brain differs from the memristor. (You can find several pieces about memrisors here including this August 24, 2017 post about a derivative, a neuristor).  This approach comes from scientists at Purdue University and employs a quantum material. From an Aug. 15, 2017 news item on phys.org,

A new computing technology called “organismoids” mimics some aspects of human thought by learning how to forget unimportant memories while retaining more vital ones.

“The human brain is capable of continuous lifelong learning,” said Kaushik Roy, Purdue University’s Edward G. Tiedemann Jr. Distinguished Professor of Electrical and Computer Engineering. “And it does this partially by forgetting some information that is not critical. I learn slowly, but I keep forgetting other things along the way, so there is a graceful degradation in my accuracy of detecting things that are old. What we are trying to do is mimic that behavior of the brain to a certain extent, to create computers that not only learn new information but that also learn what to forget.”

The work was performed by researchers at Purdue, Rutgers University, the Massachusetts Institute of Technology, Brookhaven National Laboratory and Argonne National Laboratory.

Central to the research is a ceramic “quantum material” called samarium nickelate, which was used to create devices called organismoids, said Shriram Ramanathan, a Purdue professor of materials engineering.

A video describing the work has been produced,

An August 14, 2017 Purdue University news release by Emil Venere, which originated the news item,  details the work,

“These devices possess certain characteristics of living beings and enable us to advance new learning algorithms that mimic some aspects of the human brain,” Roy said. “The results have far reaching implications for the fields of quantum materials as well as brain-inspired computing.”

When exposed to hydrogen gas, the material undergoes a massive resistance change, as its crystal lattice is “doped” by hydrogen atoms. The material is said to breathe, expanding when hydrogen is added and contracting when the hydrogen is removed.

“The main thing about the material is that when this breathes in hydrogen there is a spectacular quantum mechanical effect that allows the resistance to change by orders of magnitude,” Ramanathan said. “This is very unusual, and the effect is reversible because this dopant can be weakly attached to the lattice, so if you remove the hydrogen from the environment you can change the electrical resistance.”

When hydrogen is exposed to the material, it splits into a proton and an electron, and the electron attaches to the nickel, temporarily causing the material to become an insulator.

“Then, when the hydrogen comes out, this material becomes conducting again,” Ramanathan said. “What we show in this paper is the extent of conduction and insulation can be very carefully tuned.”

This changing conductance and the “decay of that conductance over time” is similar to a key animal behavior called habituation.

“Many animals, even organisms that don’t have a brain, possess this fundamental survival skill,” Roy said. “And that’s why we call this organismic behavior. If I see certain information on a regular basis, I get habituated, retaining memory of it. But if I haven’t seen such information over a long time, then it slowly starts decaying. So, the behavior of conductance going up and down in exponential fashion can be used to create a new computing model that will incrementally learn and at same time forget things in a proper way.”

The researchers have developed a “neural learning model” they have termed adaptive synaptic plasticity.

“This could be really important because it’s one of the first examples of using quantum materials directly for solving a major problem in neural learning,” Ramanathan said.

The researchers used the organismoids to implement the new model for synaptic plasticity.

“Using this effect we are able to model something that is a real problem in neuromorphic computing,” Roy said. “For example, if I have learned your facial features I can still go out and learn someone else’s features without really forgetting yours. However, this is difficult for computing models to do. When learning your features, they can forget the features of the original person, a problem called catastrophic forgetting.”

Neuromorphic computing is not intended to replace conventional general-purpose computer hardware, based on complementary metal-oxide-semiconductor transistors, or CMOS. Instead, it is expected to work in conjunction with CMOS-based computing. Whereas CMOS technology is especially adept at performing complex mathematical computations, neuromorphic computing might be able to perform roles such as facial recognition, reasoning and human-like decision making.

Roy’s team performed the research work on the plasticity model, and other collaborators concentrated on the physics of how to explain the process of doping-driven change in conductance central to the paper. The multidisciplinary team includes experts in materials, electrical engineering, physics, and algorithms.

“It’s not often that a materials science person can talk to a circuits person like professor Roy and come up with something meaningful,” Ramanathan said.

Organismoids might have applications in the emerging field of spintronics. Conventional computers use the presence and absence of an electric charge to represent ones and zeroes in a binary code needed to carry out computations. Spintronics, however, uses the “spin state” of electrons to represent ones and zeros.

It could bring circuits that resemble biological neurons and synapses in a compact design not possible with CMOS circuits. Whereas it would take many CMOS devices to mimic a neuron or synapse, it might take only a single spintronic device.

In future work, the researchers may demonstrate how to achieve habituation in an integrated circuit instead of exposing the material to hydrogen gas.

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

Habituation based synaptic plasticity and organismic learning in a quantum perovskite by Fan Zuo, Priyadarshini Panda, Michele Kotiuga, Jiarui Li, Mingu Kang, Claudio Mazzoli, Hua Zhou, Andi Barbour, Stuart Wilkins, Badri Narayanan, Mathew Cherukara, Zhen Zhang, Subramanian K. R. S. Sankaranarayanan, Riccardo Comin, Karin M. Rabe, Kaushik Roy, & Shriram Ramanathan. Nature Communications 8, Article number: 240 (2017) doi:10.1038/s41467-017-00248-6 Published online: 14 August 2017

This paper is open access.

Nontoxic, biodegradable orthopedic implant for damaged bones

Unlike most of the science items on phys.org this April 14, 2017 news item is not a publication announcement,

Purdue University researchers are developing a nontoxic, biodegradable orthopedic implant that could be safely absorbed by the body after providing adequate support to damaged bones.

The development of the technology originated in the lab of Lia Stanciu, a professor of materials engineering at Purdue in 2009. The technology could eliminate the need for a second surgery to remove conventional hardware.

“Currently, most implants use stainless steel and titanium alloys for strength. This can cause long-term change in the mechanics of the specific region and eventual long-term deterioration,” Stanciu said. “Additionally medical operations that require an orthopedic implant must be followed-up with a second surgery to remove the implant or the accompanying hardware of the implant resulting in higher medical costs and an increased risk of complications.”

An April 13, 2017 Purdue University news release, which originated the news item, provides a bit more detail and a hint as to what may have occasioned the news release,

Co-inventors of the technology are Stanciu; Eric Nauman, a professor in Purdue’s College of Engineering and director of the College of Engineering Honors Programs; Michael J Heiden, a PhD candidate; and Mahdi Dehestani, a graduate research assistant, both in Purdue’s School of Materials Engineering.

Nauman said the resorbable metal technology provides superior properties compared to conventional metals.

“The implant has high porosity, which is empty space in the material, in which optimal vascular invasion can occur. This provides a way for cells to optimally absorb the material,” he said. “Our technology is able to provide short-term fixation but eliminate the need for long-term hardware such as titanium or stainless steel that may require second surgeries to be retrieved,”

The orthopedic implant also uses manganese, which provides a better degradation rate, Stanciu added.

“Current resorbable metals are made with magnesium; however, this provides many adverse side effects to the body and degrades very quickly,” she said. “We decided to use manganese instead of magnesium. Through studies we found that we can control the degradation rates from 22 millimeters per year to 1.2 millimeters per year pretty consistently. We also saw that manganese has a very good corrosion rate over time.”

Nauman said the technology still exhibits the usual benefits associated with using biomaterials.

“With this technology we are able to tailor the surfaces such as de-alloying the surface to provide a better material for cells to grab on to and grow,” he said. “We were also able to show that we could control cell attachment proliferation, an increase of the number of cells. Our technology still has all these usual benefits in addition to controlling the degradation rates of the metals.”

The Purdue Research Foundation’s Office of Technology Commercialization has patented the technology and it is available for license. For information call 765-588-3470 or email innovation@prf.org.

I believe they’re looking for a commercial partner of some kind.

Skin-like electronic bandage

Not sure how I feel about an electronic bandage, presumably it won’t electrocute me should it encounter my blood. If the Nov. 17, 2016 news item on phys.org is to be believed, it’s more sensor than bandage,

A skin-like biomedical technology that uses a mesh of conducting nanowires and a thin layer of elastic polymer might bring new electronic bandages that monitor biosignals for medical applications and provide therapeutic stimulation through the skin.

The biomedical device mimics the human skin’s elastic properties and sensory capabilities.

“It can intimately adhere to the skin and simultaneously provide medically useful biofeedback such as electrophysiological signals,” said Chi Hwan Lee, an assistant professor of biomedical engineering and mechanical engineering at Purdue University. “Uniquely, this work combines high-quality nanomaterials into a skin-like device, thereby enhancing the mechanical properties.”

The device could be likened to an electronic bandage and might be used to treat medical conditions using thermotherapeutics, where heat is applied to promote vascular flow for enhanced healing, said Lee, who worked with a team that includes Purdue graduate student Min Ku Kim.

A November 17, 2016 Purdue University news release by Emil Venere, which originated the news item, provides more insight into the work,

Traditional approaches to developing such a technology have used thin films made of ductile metals such as gold, silver and copper.

“The problem is that these thin films are susceptible to fractures by over-stretching and cracking,” Lee said. “Instead of thin films we use nanowire mesh film, which makes the device more resistive to stretching and cracking than otherwise possible. In addition, the nanowire mesh film has very high surface area compared to conventional thin films, with more than 1,000 times greater surface roughness. So once you attach it to the skin the adhesion is much higher, reducing the potential of inadvertent delamination.”

Findings are detailed in a research publication appearing online in October [2016] in Advanced Materials. The paper is also available online at http://onlinelibrary.wiley.com/doi/10.1002/adma.201603878/full and was authored by Kim; postdoctoral researcher Seungyong Han at the University of Illinois, Urbana-Champaign; Purdue graduate student Dae Seung Wie; Oklahoma State University assistant professor Shuodao Wang and postdoctoral researcher Bo Wang; and Lee.

The conducting nanowires are around 50 nanometers in diameter and more than 150 microns long and are embedded inside a thin layer of elastomer, or elastic polymer, about 1.5 microns thick. To demonstrate its utility in medical diagnostics, the device was used to record electrophysiological signals from the heart and muscles. A YouTube video about the research is available at https://youtu.be/tYRebHNi6p4.

“Recording the electrophysiological signals from the skin can provide wearers and clinicians with quantitative measures of the heart’s activity or the muscle’s activity,” Lee said.

Much of the research was performed in the Birck Nanotechnology Center in Purdue’s Discovery Park.

“The nanowires mesh film was initially formed on a conventional silicon wafer with existing micro- and nano-fabrication technologies. Our unique technique, called a crack-driven transfer printing technique, allows us to controllably peel off the device layer from the silicon wafer, and then apply onto the skin,” Lee said.

The Oklahoma State researchers contributed theoretical simulations related to the underlying mechanics of the devices, and Seungyong Han synthesized and provided the conducting nanowires.

Future research will be dedicated to developing a transdermal drug-delivery bandage that would transport medications through the skin in an electronically controlled fashion. Such a system might include built-in sensors to detect the level of injury and autonomously deliver the appropriate dose of drugs.

Here’s a link to and a citation for the paper mentioned in the news release,

Mechanically Reinforced Skin-Electronics with Networked Nanocomposite Elastomer by Seungyong Han, Min Ku Kim, Bo Wang, Dae Seung Wie, Shuodao Wang, and Chi Hwan Lee. Advanced Materials DOI: 10.1002/adma.201603878 Version of Record online: 7 OCT 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall but you can watch the video mentioned in the news release,

It seems that liquids won’t be a problem with regard to electrocution and I notice they keep calling it a biopatch not a bandaid.

Treating graphene with lasers for paper-based electronics

Engineers at Iowa State University have found a way they hope will make it easier to commercialize graphene. A Sept. 1, 2016 news item on phys.org describes the research,

The researchers in Jonathan Claussen’s lab at Iowa State University (who like to call themselves nanoengineers) have been looking for ways to use graphene and its amazing properties in their sensors and other technologies.

Graphene is a wonder material: The carbon honeycomb is just an atom thick. It’s great at conducting electricity and heat; it’s strong and stable. But researchers have struggled to move beyond tiny lab samples for studying its material properties to larger pieces for real-world applications.

Recent projects that used inkjet printers to print multi-layer graphene circuits and electrodes had the engineers thinking about using it for flexible, wearable and low-cost electronics. For example, “Could we make graphene at scales large enough for glucose sensors?” asked Suprem Das, an Iowa State postdoctoral research associate in mechanical engineering and an associate of the U.S. Department of Energy’s Ames Laboratory.

But there were problems with the existing technology. Once printed, the graphene had to be treated to improve electrical conductivity and device performance. That usually meant high temperatures or chemicals – both could degrade flexible or disposable printing surfaces such as plastic films or even paper.

Das and Claussen came up with the idea of using lasers to treat the graphene. Claussen, an Iowa State assistant professor of mechanical engineering and an Ames Laboratory associate, worked with Gary Cheng, an associate professor at Purdue University’s School of Industrial Engineering, to develop and test the idea.

A Sept. 1, 2016 Iowa State University news release (also on EurekAlert), which originated the news item, provides more detail about the intellectual property, as well as, the technology,

… They found treating inkjet-printed, multi-layer graphene electric circuits and electrodes with a pulsed-laser process improves electrical conductivity without damaging paper, polymers or other fragile printing surfaces.

“This creates a way to commercialize and scale-up the manufacturing of graphene,” Claussen said.

Two major grants are supporting the project and related research: a three-year grant from the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 11901762 and a three-year grant from the Roy J. Carver Charitable Trust. Iowa State’s College of Engineering and department of mechanical engineering are also supporting the research.

The Iowa State Research Foundation Inc. has filed for a patent on the technology.

“The breakthrough of this project is transforming the inkjet-printed graphene into a conductive material capable of being used in new applications,” Claussen said.

Those applications could include sensors with biological applications, energy storage systems, electrical conducting components and even paper-based electronics.

To make all that possible, the engineers developed computer-controlled laser technology that selectively irradiates inkjet-printed graphene oxide. The treatment removes ink binders and reduces graphene oxide to graphene – physically stitching together millions of tiny graphene flakes. The process makes electrical conductivity more than a thousand times better.

“The laser works with a rapid pulse of high-energy photons that do not destroy the graphene or the substrate,” Das said. “They heat locally. They bombard locally. They process locally.”

That localized, laser processing also changes the shape and structure of the printed graphene from a flat surface to one with raised, 3-D nanostructures. The engineers say the 3-D structures are like tiny petals rising from the surface. The rough and ridged structure increases the electrochemical reactivity of the graphene, making it useful for chemical and biological sensors.

All of that, according to Claussen’s team of nanoengineers, could move graphene to commercial applications.

“This work paves the way for not only paper-based electronics with graphene circuits,” the researchers wrote in their paper, “it enables the creation of low-cost and disposable graphene-based electrochemical electrodes for myriad applications including sensors, biosensors, fuel cells and (medical) devices.”

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

3D nanostructured inkjet printed graphene via UV-pulsed laser irradiation enables paper-based electronics and electrochemical devices by Suprem R. Das, Qiong Nian, Allison A. Cargill, John A. Hondred, Shaowei Ding, Mojib Saei, Gary J. Cheng, and   Jonathan C. Claussen. Nanoscale, 2016,8, 15870-15879 DOI: 10.1039/C6NR04310K First published online 12 Jul 2016

This paper is open access but you do need to have registered for your free account to access the material.

Biodegradable films from cellulose nanofibrils

A team at Purdue University (Indiana, US) has developed a new process for biodegradable films based on cellulose according to a June 8, 2016 news item on phys.org,

Purdue University researchers have developed tough, flexible, biodegradable films from cellulose, the main component of plant cell walls. The films could be used for products such as food packaging, agricultural groundcovers, bandages and capsules for medicine or bioactive compounds.

Food scientists Srinivas Janaswamy and Qin Xu engineered the cellophane-like material by solubilizing cellulose using zinc chloride, a common inorganic salt, and adding calcium ions to cause the cellulose chains to become tiny fibers known as nanofibrils, greatly increasing the material’s tensile strength. The zinc chloride and calcium ions work together to form a gel network, allowing the researchers to cast the material into a transparent, food-grade film.

A June 7, 2016 Purdue University news release by Natalie van Hoose, which originated the news item, discusses the need for these films and provides a few more technical details about the work (Note: A link has been removed),

“We’re looking for innovative ways to adapt and use cellulose – an inexpensive and widely available material – for a range of food, biomedical and pharmaceutical applications,” said Janaswamy, research assistant professor of food science and principal author of the study. “Though plastics have a wide variety of applications, their detrimental impact on the environment raises a critical need for alternative materials. Cellulose stands out as a viable option, and our process lays a strong foundation for developing new biodegradable plastics.”

Cellulose’s abundance, renewability and ability to biodegrade make it a promising substitute for petroleum-based products. While a variety of products such as paper, cellophane and rayon are made from cellulose, its tightly interlinked structure and insolubility – qualities that give plants strength and protection – make it a challenging material to work with.

Janaswamy and Xu loosened the cellulose network by adding zinc chloride, which helps push cellulose’s closely packed sheets apart, allowing water to penetrate and solubilize it. Adding calcium ions spurs the formation of nanofibrils through strong bonds between the solubilized cellulose sheets. The calcium ions boost the tensile strength of the films by about 250 percent.

The production process preserves the strength and biodegradability of cellulose while rendering it transparent and flexible.

Because the zinc chloride can be recycled to repeat the process, the method offers an environmentally friendly alternative to conventional means of breaking down cellulose, which tend to rely on toxic chemicals and extreme temperatures.

“Products based on this film can have a no-waste lifecycle,” said Xu, research assistant professor of food science and first author of the study. “This process allows us to create a valuable product from natural materials – including low-value or waste materials such as corn stover or wood chips- that can eventually be returned to the Earth.”

The methodology could be adapted to mass-produce cellulose films, the researchers said.

The next step in the project is to find ways of making the cellulose film insoluble to water while maintaining its ability to biodegrade.

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

A facile route to prepare cellulose-based films by Qin Xu, Chen Chen, Katelyn Rosswurm, Tianming Yao, Srinivas Janaswamy. Carbohydrate Polymers Volume 149, 20 September 2016, Pages 274–281 doi:10.1016/j.carbpol.2016.04.114

This paper is behind a paywall.

Boosting chip speeds with graphene

There’s a certain hysteria associated with chip speeds as engineers and computer scientists try to achieve the ever improved speed times that consumers have enjoyed for some decades. The question looms, is there some point at which we can no longer improve the speed? Well, we haven’t reached that point yet according to a June 18, 2015 news item on Nanotechnology Now,

Stanford engineers find a simple yet clever way to boost chip speeds: Inside each chip are millions of tiny wires to transport data; wrapping them in a protective layer of graphene could boost speeds by up to 30 percent. [emphasis mine]

A June 16, 2015 Stanford University news release by Tom Abate (also on EurekAlert but dated June 17, 2015), which originated the news item, describes how computer chips are currently designed and the redesign which yields more speed,

A typical computer chip includes millions of transistors connected with an extensive network of copper wires. Although chip wires are unimaginably short and thin compared to household wires both have one thing in common: in each case the copper is wrapped within a protective sheath.

For years a material called tantalum nitride has formed protective layer in chip wires.

Now Stanford-led experiments demonstrate that a different sheathing material, graphene, can help electrons scoot through tiny copper wires in chips more quickly.

Graphene is a single layer of carbon atoms arranged in a strong yet thin lattice. Stanford electrical engineer H.-S. Philip Wong says this modest fix, using graphene to wrap wires, could allow transistors to exchange data faster than is currently possible. And the advantages of using graphene would become greater in the future as transistors continue to shrink.

Wong led a team of six researchers, including two from the University of Wisconsin-Madison, who will present their findings at the Symposia of VLSI Technology and Circuits in Kyoto, a leading venue for the electronics industry.

Ling Li, a graduate student in electrical engineering at Stanford and first author of the research paper, explained why changing the exterior wrapper on connecting wires can have such a big impact on chip performance.

It begins with understanding the dual role of this protective layer: it isolates the copper from the silicon on the chip and also serve to conduct electricity.

On silicon chips, the transistors act like tiny gates to switch electrons on or off. That switching function is how transistors process data.

The copper wires between the transistors transport this data once it is processed.

The isolating material–currently tantalum nitride–keeps the copper from migrating into the silicon transistors and rendering them non-functional.

Why switch to graphene?

Two reasons, starting with the ceaseless desire to keep making electronic components smaller.

When the Stanford team used the thinnest possible layer of tantalum nitride needed to perform this isolating function, they found that the industry-standard was eight times thicker than the graphene layer that did the same work.

Graphene had a second advantage as a protective sheathing and here it’s important to differentiate how this outer layer functions in chip wires versus a household wires.

In house wires the outer layer insulates the copper to prevent electrocution or fires.

In a chip the layer around the wires is a barrier to prevent copper atoms from infiltrating the silicon. Were that to happen the transistors would cease to function. So the protective layer isolates the copper from the silicon

The Stanford experiment showed that graphene could perform this isolating role while also serving as an auxiliary conductor of electrons. Its lattice structure allows electrons to leap from carbon atom to carbon atom straight down the wire, while effectively containing the copper atoms within the copper wire.

These benefits–the thinness of the graphene layer and its dual role as isolator and auxiliary conductor–allow this new wire technology to carry more data between transistors, speeding up overall chip performance in the process.

In today’s chips the benefits are modest; a graphene isolator would boost wire speeds from four percent to 17 percent, depending on the length of the wire. [emphasis mine]

But as transistors and wires continue to shrink in size, the benefits of the ultrathin yet conductive graphene isolator become greater. [emphasis mine] The Stanford engineers estimate that their technology could increase wire speeds by 30 percent in the next two generations

The Stanford researchers think the promise of faster computing will induce other researchers to get interested in wires, and help to overcome some of the hurdles needed to take this proof of principle into common practice.

This would include techniques to grow graphene, especially growing it directly onto wires while chips are being mass-produced. In addition to his University of Wisconsin collaborator Professor Michael Arnold, Wong cited Purdue University Professor Zhihong Chen. Wong noted that the idea of using graphene as an isolator was inspired by Cornell University Professor Paul McEuen and his pioneering research on the basic properties of this marvelous material. Alexander Balandin of the University of California-Riverside has also made contributions to using graphene in chips.

“Graphene has been promised to benefit the electronics industry for a long time, and using it as a copper barrier is perhaps the first realization of this promise,” Wong said.

I gather they’ve decided to highlight the most optimistic outcomes.

Call for nanoHUB User Conference proposals *deadline extension*

The deadline for the conference is June 15, 2015. Here’s more from a June 6, 2015 nanoHUB announcement,

Conference Description: The nanoHUB User Conference brings together users from research, education, and industry to network and learn from each other as well as from the nanoHUB team. Join us this year at Purdue University and hear from experienced users how nanoHUB is integrated into their research/classrooms, discover how nanoHUB is used in projects, and learn how to apply this information through a series of workshops offered by nanoHUB experts.

Abstract submission deadline is June 15th, 2015. *The deadline has been extend to Monday, June 22, 2105.* Additional information and instructions can be found here.

The conference will be held August 31st – September 1st, 2015, at Purdue University in West Lafayette, Indiana, USA. Registration for the conference is now open at: http://nanohub.org/newsletter/track/click/?t=IDAgRTVDNTAxNiBFNTQ1MTU1IDI0MDQ3NzM0MzUxNTI0RjFFNTI1OA%3D%3D&l=https%3A%2F%2Fnanohub.org%2Fgroups%2Fconference%2Fregistration


Abstract Submissions Deadline

June 15th, 2015 *Extended to Monday, June 22, 2015*

Authors Notified of Acceptance

July 15th, 2015

Poster Submissions Deadline

August 1st, 2015

For anyone who read this out of curiosity, here’s a brief description of nanoHUB from the website’s About Us webpage,

What is nanoHUB.org?

nanoHUB.org is the premier place for computational nanotechnology research, education, and collaboration. Our site hosts a rapidly growing collection of Simulation Programs for nanoscale phenomena that run in the cloud and are accessible through a web browser. In addition to simulation devices, nanoHUB provides Online Presentations, Courses, Learning Modules, Podcasts, Animations, Teaching Materials, and more. These resources help users learn about our simulation programs and about nanotechnology in general. Our site offers researchers a venue to explore, collaborate, and publish content, as well. Much of these collaborative efforts occur via Workspaces and User groups.

Authors of content published on nanoHUB.org represent a broad and growing cross-section of the nanotechnology community. Their work impacts industry, education, and governmental organizations around the world, as shown by the animated user location map below. The majority of nanoHUB users are affiliated with academic institutions, while other individuals are part of government and industry groups. nanoHUB makes public detailed usage analysis for the site with a degree of transparency uncommon among other sites.

nanoHUB content has been cited over 1,100 times in the scientific literature. These papers collectively have an h-index of 57, and the majority of them are by authors not affiliated with the Network for Computational Nanotechnology, the project that produces nanoHUB. Through automated assessment of user behavior, we have identified over 1100 clusters at 185 institutions using nanoHUB tools in the classroom. nanoHUB annual uptime regularly exceeds 99 percent.

Getting back to the call, good luck to everyone who makes a submission.

*Deadline extension updated added June 15, 2015.

3D printing soft robots and flexible electronics with metal alloys

This research comes from Purdue University (Indiana, US) which seems to be on a publishing binge these days. From an April 7, 2015 news item on Nanowerk,

New research shows how inkjet-printing technology can be used to mass-produce electronic circuits made of liquid-metal alloys for “soft robots” and flexible electronics.

Elastic technologies could make possible a new class of pliable robots and stretchable garments that people might wear to interact with computers or for therapeutic purposes. However, new manufacturing techniques must be developed before soft machines become commercially feasible, said Rebecca Kramer, an assistant professor of mechanical engineering at Purdue University.

“We want to create stretchable electronics that might be compatible with soft machines, such as robots that need to squeeze through small spaces, or wearable technologies that aren’t restrictive of motion,” she said. “Conductors made from liquid metal can stretch and deform without breaking.”

A new potential manufacturing approach focuses on harnessing inkjet printing to create devices made of liquid alloys.

“This process now allows us to print flexible and stretchable conductors onto anything, including elastic materials and fabrics,” Kramer said.

An April 7, 2015 Purdue University news release (also on EurekAlert) by Emil Venere, which originated the news item, expands on the theme,

A research paper about the method will appear on April 18 [2015] in the journal Advanced Materials. The paper generally introduces the method, called mechanically sintered gallium-indium nanoparticles, and describes research leading up to the project. It was authored by postdoctoral researcher John William Boley, graduate student Edward L. White and Kramer.

A printable ink is made by dispersing the liquid metal in a non-metallic solvent using ultrasound, which breaks up the bulk liquid metal into nanoparticles. This nanoparticle-filled ink is compatible with inkjet printing.

“Liquid metal in its native form is not inkjet-able,” Kramer said. “So what we do is create liquid metal nanoparticles that are small enough to pass through an inkjet nozzle. Sonicating liquid metal in a carrier solvent, such as ethanol, both creates the nanoparticles and disperses them in the solvent. Then we can print the ink onto any substrate. The ethanol evaporates away so we are just left with liquid metal nanoparticles on a surface.”

After printing, the nanoparticles must be rejoined by applying light pressure, which renders the material conductive. This step is necessary because the liquid-metal nanoparticles are initially coated with oxidized gallium, which acts as a skin that prevents electrical conductivity.

“But it’s a fragile skin, so when you apply pressure it breaks the skin and everything coalesces into one uniform film,” Kramer said. “We can do this either by stamping or by dragging something across the surface, such as the sharp edge of a silicon tip.”

The approach makes it possible to select which portions to activate depending on particular designs, suggesting that a blank film might be manufactured for a multitude of potential applications.

“We selectively activate what electronics we want to turn on by applying pressure to just those areas,” said Kramer, who this year was awarded an Early Career Development award from the National Science Foundation, which supports research to determine how to best develop the liquid-metal ink.

The process could make it possible to rapidly mass-produce large quantities of the film.

Future research will explore how the interaction between the ink and the surface being printed on might be conducive to the production of specific types of devices.

“For example, how do the nanoparticles orient themselves on hydrophobic versus hydrophilic surfaces? How can we formulate the ink and exploit its interaction with a surface to enable self-assembly of the particles?” she said.

The researchers also will study and model how individual particles rupture when pressure is applied, providing information that could allow the manufacture of ultrathin traces and new types of sensors.

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

Nanoparticles: Mechanically Sintered Gallium–Indium Nanoparticles by John William Boley, Edward L. White and Rebecca K. Kramer. Advanced Materials Volume 27, Issue 14, page 2270, April 8, 2015 DOI: 10.1002/adma.201570094 Article first published online: 7 APR 2015

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This article is behind a paywall.

Cellullose nanocrystals (CNC) and better concrete

Earlier this week in a March 30, 2015 post, I was bemoaning the dearth of applications for cellulose nanocrystals (CNC) with concomitant poor prospects for commercialization and problems for producers such as Canada’s CelluForce. Possibly this work at Purdue University (Indiana, US) will help address some of those issues (from a March 31, 2015 news item on Nanowerk),

Cellulose nanocrystals derived from industrial byproducts have been shown to increase the strength of concrete, representing a potential renewable additive to improve the ubiquitous construction material.

The cellulose nanocrystals (CNCs) could be refined from byproducts generated in the paper, bioenergy, agriculture and pulp industries. They are extracted from structures called cellulose microfibrils, which help to give plants and trees their high strength, lightweight and resilience. Now, researchers at Purdue University have demonstrated that the cellulose nanocrystals can increase the tensile strength of concrete by 30 percent.

A March 31, 2015 Purdue University news release by Emil Venere, which originated the news item, further describes the research published in print as of February 2015 (Note: A link has been removed),

One factor limiting the strength and durability of today’s concrete is that not all of the cement particles are hydrated after being mixed, leaving pores and defects that hamper strength and durability.

“So, in essence, we are not using 100 percent of the cement,” Zavattieri [Pablo Zavattieri, an associate professor in the Lyles School of Civil Engineering] said.

However, the researchers have discovered that the cellulose nanocrystals increase the hydration of the concrete mixture, allowing more of it to cure and potentially altering the structure of concrete and strengthening it.  As a result, less concrete needs to be used.

The cellulose nanocrystals are about 3 to 20 nanometers wide by 50-500 nanometers long – or about 1/1,000th the width of a grain of sand – making them too small to study with light microscopes and difficult to measure with laboratory instruments. They come from a variety of biological sources, primarily trees and plants.

The concrete was studied using several analytical and imaging techniques. Because chemical reactions in concrete hardening are exothermic, some of the tests measured the amount of heat released, indicating an increase in hydration of the concrete. The researchers also hypothesized the precise location of the nanocrystals in the cement matrix and learned how they interact with cement particles in both fresh and hardened concrete. The nanocrystals were shown to form little inlets for water to better penetrate the concrete.

The research dovetails with the goals of P3Nano, a public-private partnership supporting development and use of wood-based nanomaterial for a wide-range of commercial products.

“The idea is to support and help Purdue further advance the CNC-Cement technology for full-scale field trials and the potential for commercialization,” Zavattieri said.

The researchers have provided an image,

This transmission electron microscope image shows cellulose nanocrystals, tiny structures derived from renewable sources that might be used to create a new class of biomaterials with many potential applications. The structures have been shown to increase the strength of concrete. (Purdue Life Sciences Microscopy Center)

This transmission electron microscope image shows cellulose nanocrystals, tiny structures derived from renewable sources that might be used to create a new class of biomaterials with many potential applications. The structures have been shown to increase the strength of concrete. (Purdue Life Sciences Microscopy Center)

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

The influence of cellulose nanocrystal additions on the performance of cement paste by Yizheng Cao, Pablo Zavaterri, Jeff Youngblood, Robert Moon, and Jason Weiss. Cement and Concrete Composites, Volume 56, February 2015, Pages 73–83  DOI: 10.1016/j.cemconcomp.2014.11.008 Available online 18 November 2014

The paper is behind a paywall.

One final note, cellulose nanocrystals (CNC) may also be referred to nanocrystalline cellulose (NCC).


Nano for car lubricants and for sensors on dashboards

I have two car-oriented news items today. The first concerns the introduction of carbon nanospheres into lubricants as a means of reducing friction. From a March 5, 2015 news item on Nanowerk,

Tiny, perfectly smooth carbon spheres added to motor oil have been shown to reduce friction and wear typically seen in engines by as much as 25 percent, suggesting a similar enhancement in fuel economy.

The researchers also have shown how to potentially mass-produce the spheres, making them hundreds of times faster than previously possible using ultrasound to speed chemical reactions in manufacturing.

“People have been making these spheres for about the last 10 years, but what we discovered was that instead of taking the 24 hours of synthesis normally needed, we can make them in 5 minutes,” said Vilas Pol, an associate professor of chemical engineering at Purdue University.

The spheres are 100-500 nanometers in diameter, a range that generally matches the “surface roughness” of moving engine components.

“So the spheres are able to help fill in these areas and reduce friction,” said mechanical engineering doctoral student Abdullah A. Alazemi.

A March 4, 2015 Purdue University news release by Emil Venere, which originated the news item, elaborates on the impact this finding could have (Note: A link has been removed),

Tests show friction is reduced by 10 percent to 25 percent when using motor oil containing 3 percent of the spheres by weight.

“Reducing friction by 10 to 25 percent would be a significant improvement,” Sadeghi said. “Many industries are trying to reduce friction through modification of lubricants. The primary benefit to reducing friction is improved fuel economy.”

Friction is greatest when an engine is starting and shutting off, so improved lubrication is especially needed at those times.

“Introducing microspheres helps separate the surfaces because the spheres are free to move,” Alazemi said. “It also is possible that these spheres are rolling and acting as little ball bearings, but further research is needed to confirm this.” [emphasis mine]

Findings indicate adding the spheres did not change the viscosity of the oil.

“It’s very important not to increase the viscosity because you want to maintain the fluidity of the oil so that it can penetrate within engine parts,” Alazemi said.

The spheres are created using ultrasound to produce bubbles in a fluid containing a chemical compound called resorcinol and formaldehyde. The bubbles expand and collapse, generating heat that drives chemical reactions to produce polymer particles. These polymeric particles are then heated in a furnace to about 900 degrees Celsius, yielding the perfectly smooth spheres.

“A major innovation is that professor Pol has shown how to make lots of these spheres, which is important for potential industrial applications,” Sadeghi said.

Etacheri said, “Electron microscopy images and Raman spectra taken before and after their use show the spheres are undamaged, suggesting they can withstand the punishing environment inside engines and other machinery.”

Funding was provided by Purdue’s School of Chemical Engineering. Electron microscopy studies were performed at the Birck Nanotechnology Center in Purdue’s Discovery Park.

Future research will include work to determine whether the spheres are rolling like tiny ball bearings or merely sliding. A rolling mechanism best reduces friction and would portend well for potential applications. Future research also will determine whether the resorcinol-formaldehyde particles might themselves be used as a lubricant additive without heating them to produce pure carbon spheres.

I’m not sure why the researcher is referring to microspheres as the measurements are at the nanoscale, which should mean these are ‘nanospheres’ or, as the researchers have it in the title for their paper, ‘submicrometer spheres’.

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

Ultrasmooth Submicrometer Carbon Spheres as Lubricant Additives for Friction and Wear Reduction by Abdullah A. Alazemi, Vinodkumar Etacheri, Arthur D. Dysart, Lars-Erik Stacke, Vilas G. Pol, and Farshid Sadeghi. ACS Appl. Mater. Interfaces, Article ASAP DOI: 10.1021/acsami.5b00099 Publication Date (Web): February 17, 2015
Copyright © 2015 American Chemical Society

This paper is behind a paywall but there is an instructive image freely available,

This image taken with an electron microscope shows that tiny carbon spheres added to motor oil reduce friction and wear typically seen in engines by as much as 25 percent, suggesting a similar enhancement in fuel economy. Purdue researchers also have shown how to potentially mass-produce the spheres. (Purdue University image)

This image taken with an electron microscope shows that tiny carbon spheres added to motor oil reduce friction and wear typically seen in engines by as much as 25 percent, suggesting a similar enhancement in fuel economy. Purdue researchers also have shown how to potentially mass-produce the spheres. (Purdue University image)

My second car item concerns thin films and touch. From a March 5, 2015 news item on Azonano (Note: A link has been removed),,

Canatu, a leading manufacturer of transparent conductive films, has in partnership with Schuster Group [based in Germany] and Display Solution AG [based in Germany], showcased a pioneering 3D encapsulated touch sensor for the automotive industry.

The partnership is delivering the first ever, button free, 3D shaped true multitouch panel for automotives, being the first to bring much anticipated touch applications to dashboards and paneling. The demonstrator provides an example of multi-functional display with 5 finger touch realized in IML [in mould labeling] technology.

A March 5, 2015 Canatu press release, which originated the news item, provides more details about the technology and some insight into future plans,

The demonstrator provides an example of multi-functional display with 5 finger touch realized in IML technology. The integration of touch applications to dashboards and other paneling in cars has long been a desired by automotive designers but a suitable technology was not available. Finally the technology is now here. Canatu’s CNB™ (Carbon NanoBud®) In-Mold Film, with its unique stretch properties provides a clear path to the eventual replacement of mechanical controls with 3D touch sensors. The touch application was made using an existing mass manufacturing tool and industry standard processes.

Specifically designed for automobile center consoles and dashboards, household machines, wearable devices, industrial user interfaces, commercial applications and consumer devices, CNB™ In-Mold Films can be easily formed into shape. The film is first patterned to the required touch functionality, then formed, then back-molded by injection molding, resulting in a unique 3D shape with multitouch functionality.

With a bending radius of 1mm, CNB™ In-Mold Films can bring touch to almost any surface imaginable. The unique properties of CNB™ In-Mold Films are unmatched as no other film on the market can be stretched 120% and molded without losing their conductivity.

You can find out more about Canatu, based in Finland, here.