Tag Archives: University of Wisconsin-Madison

Center for Sustainable Nanotechnology or how not to poison and make the planet uninhabitable

I received notice of the Center for Sustainable Nanotechnology’s newest deal with the US National Science Foundation in an August 31, 2015 email University of Wisconsin-Madison (UWM) news release,

The Center for Sustainable Nanotechnology, a multi-institutional research center based at the University of Wisconsin-Madison, has inked a new contract with the National Science Foundation (NSF) that will provide nearly $20 million in support over the next five years.

Directed by UW-Madison chemistry Professor Robert Hamers, the center focuses on the molecular mechanisms by which nanoparticles interact with biological systems.

Nanotechnology involves the use of materials at the smallest scale, including the manipulation of individual atoms and molecules. Products that use nanoscale materials range from beer bottles and car wax to solar cells and electric and hybrid car batteries. If you read your books on a Kindle, a semiconducting material manufactured at the nanoscale underpins the high-resolution screen.

While there are already hundreds of products that use nanomaterials in various ways, much remains unknown about how these modern materials and the tiny particles they are composed of interact with the environment and living things.

“The purpose of the center is to explore how we can make sure these nanotechnologies come to fruition with little or no environmental impact,” explains Hamers. “We’re looking at nanoparticles in emerging technologies.”

In addition to UW-Madison, scientists from UW-Milwaukee, the University of Minnesota, the University of Illinois, Northwestern University and the Pacific Northwest National Laboratory have been involved in the center’s first phase of research. Joining the center for the next five-year phase are Tuskegee University, Johns Hopkins University, the University of Iowa, Augsburg College, Georgia Tech and the University of Maryland, Baltimore County.

At UW-Madison, Hamers leads efforts in synthesis and molecular characterization of nanomaterials. soil science Professor Joel Pedersen and chemistry Professor Qiang Cui lead groups exploring the biological and computational aspects of how nanomaterials affect life.

Much remains to be learned about how nanoparticles affect the environment and the multitude of organisms – from bacteria to plants, animals and people – that may be exposed to them.

“Some of the big questions we’re asking are: How is this going to impact bacteria and other organisms in the environment? What do these particles do? How do they interact with organisms?” says Hamers.

For instance, bacteria, the vast majority of which are beneficial or benign organisms, tend to be “sticky” and nanoparticles might cling to the microorganisms and have unintended biological effects.

“There are many different mechanisms by which these particles can do things,” Hamers adds. “The challenge is we don’t know what these nanoparticles do if they’re released into the environment.”

To get at the challenge, Hamers and his UW-Madison colleagues are drilling down to investigate the molecular-level chemical and physical principles that dictate how nanoparticles interact with living things.
Pedersen’s group, for example, is studying the complexities of how nanoparticles interact with cells and, in particular, their surface membranes.

“To enter a cell, a nanoparticle has to interact with a membrane,” notes Pedersen. “The simplest thing that can happen is the particle sticks to the cell. But it might cause toxicity or make a hole in the membrane.”

Pedersen’s group can make model cell membranes in the lab using the same lipids and proteins that are the building blocks of nature’s cells. By exposing the lab-made membranes to nanomaterials now used commercially, Pedersen and his colleagues can see how the membrane-particle interaction unfolds at the molecular level – the scale necessary to begin to understand the biological effects of the particles.

Such studies, Hamers argues, promise a science-based understanding that can help ensure the technology leaves a minimal environmental footprint by identifying issues before they manifest themselves in the manufacturing, use or recycling of products that contain nanotechnology-inspired materials.

To help fulfill that part of the mission, the center has established working relationships with several companies to conduct research on materials in the very early stages of development.

“We’re taking a look-ahead view. We’re trying to get into the technological design cycle,” Hamers says. “The idea is to use scientific understanding to develop a predictive ability to guide technology and guide people who are designing and using these materials.”

What with this initiative and the LCnano Network at Arizona State University (my April 8, 2014 posting; scroll down about 50% of the way), it seems that environmental and health and safety studies of nanomaterials are kicking into a higher gear as commercialization efforts intensify.

Audience perceptions of emerging technologies and media stories that emphasize conflict over nuance

A few names popped into my head, as soon as I saw a news release focused on audience perceptions and emerging technologies. I was right about one of the authors (Dominique Brossard of the University of Wisconsin-Madison [UWM] often writes on the topic) however, the lead author is Andrew Binder of North Carolina State University (NCSU). An August 31, 2015 NCSU news release describes a joint NCSU-UWM research project  (Note: Links have been removed),

Researchers from NC State University and the University of Wisconsin-Madison have found more evidence that how media report on emerging technologies – such as nanotechnology or genetically modified crops – influences public opinion on those subjects.

Specifically, when news stories highlight conflict in the scientific community on an emerging technology, people who accept the authority of scientists on scientific subjects are more likely to view the emerging technology as risky.

“Scientists – even scientists who disagree – often incorporate caveats and nuance into their comments on emerging technologies,” says Andrew R. Binder, lead author of a paper on the work and an associate professor of communication at NC State. “For example, a scientist may voice an opinion but note a lack of data on the subject. But that nuance is often lost in news stories.

“We wanted to know stories that present scientists as being in clear conflict, leaving out the nuance, affected the public’s perception of uncertainty on an issue – particularly compared to stories that incorporate the nuances of each scientist’s position,” Binder says.

For their experiment, the researchers had 250 college students answer a questionnaire on their deference to scientific authority and their perceptions of nanotechnology. Participants were split into four groups. Before asking about nanotechnology, one group was asked to read a news story about nanotech that quoted scientists and presented them as being in conflict; one group read a news story with quotes that showed disagreement between scientists but included nuance on each scientist’s position; one group read a story without quotes; and one group – the control group – was given no reading.

In most instances, the reading assignments did not have a significant impact on study participants’ perception of risks associated with nanotechnology. However, those participants who were both “highly deferent” to scientific authority and given the “conflict” news item perceived nanotechnology as being significantly more risky as compared to those highly deferent study participants who read the “nuance” article.

“One thing that’s interesting here is that participants who were highly deferential to scientific authority but were in the control group or read the news item without quotes – they landed about halfway between the ‘conflict’ group and the ‘nuance’ group,” Binder says. “So it would seem that the way reporters frame scientific opinion can sway an audience one way or the other.”

The researchers also found that, while an appearance of conflict can increase one’s perception of risk, it did not increase participants’ sense of certainty in their position.

As a practical matter, the findings raise questions for journalists – since scientists have limited control over how they’re portrayed in the news. Previous surveys have found that many people are deferent to scientific authority – they trust scientists – so a reporter’s decision to cut nuance or highlight conflict could make a very real impact on how the public perceives emerging technologies.

“Reporters can’t include every single detail, and scientists want to include everything,” Binder says. “So I don’t think there’s a definitive solution out there that will make everyone happy. But hopefully this will encourage both parties to meet in the middle.”

I have one comment, this research was conducted on college students whose age range is likely more restricted than what you’d find in the general populace. I don’t know if the research team has plans or more funding but it would seem the next step would be to tested a wider range to see if the results with the college students can be generalized.

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

Conflict or Caveats? Effects of Media Portrayals of Scientific Uncertainty on Audience Perceptions of New Technologies by Andrew R. Binder, Elliott D. Hillback, and Dominique Brossard. Risk Analysis DOI: 10.1111/risa.12462 Article first published online: 13 AUG 2015

© 2015 Society for Risk Analysis

This paper is behind a paywall.

Nanoscale device emits light as powerfully as an object 10,000 times its size

The potential application in the field of solar power is what most interests me in this collaborative research from the University of Wisconsin-Madison (US) and Fudan University in China. From a July 13, 2015 news item on ScienceDaily,

University of Wisconsin-Madison engineers have created a nanoscale device that can emit light as powerfully as an object 10,000 times its size. It’s an advance that could have huge implications for everything from photography to solar power.

In a paper published July 10 [2015] in the journal Physical Review Letters, Zongfu Yu, an assistant professor of electrical and computer engineering, and his collaborators describe a nanoscale device that drastically surpasses previous technology in its ability to scatter light. They showed how a single nanoresonator can manipulate light to cast a very large “reflection.” The nanoresonator’s capacity to absorb and emit light energy is such that it can make itself — and, in applications, other very small things — appear 10,000 times as large as its physical size.

A July 13, 2015 University of Wisconsin-Madison news release (also on EurekAlert) by Scott Gordon, which originated the news item, expands on the theme,

“Making an object look 10,000 times larger than its physical size has lots of implications in technologies related to light,” Yu says.

The researchers realized the advance through materials innovation and a keen understanding of the physics of light. Much like sound, light can resonate, amplifying itself as the surrounding environment manipulates the physical properties of its wave energy. The researchers took advantage of this by creating an artificial material in which the wavelength of light is much larger than in a vacuum, which allows light waves to resonate more powerfully.

The device condenses light to a size smaller than its wavelength, meaning it can gather a lot of light energy, and then scatters the light over a very large area, harnessing its output for imaging applications that make microscopic particles appear huge.

“The device makes an object super-visible by enlarging its optical appearance with this super-strong scattering effect,” says Ming Zhou, a Ph.D. student in Yu’s group and lead author of the paper.

Much as a very thin string on a guitar can absorb a large amount of acoustic energy from its surroundings and begin to vibrate in sympathy, this one very small optical device can receive light energy from all around and yield a surprisingly strong output. In imaging, this presents clear advantages over conventional lenses, whose light-gathering capacity is limited by direction and size.

“We are developing photodetectors based on this technology and, for example, it could be helpful for photographers wanting to shoot better quality pictures in weak light conditions,” Yu says.

Given the nanoresonator’s capacity to absorb large amounts of light energy, the technology also has potential in applications that harvest the sun’s energy with high efficiency. In addition, Yu envisions simply letting the resonator emit that energy in the form of infrared light toward the sky, which is very cold. Because the nanoresonator has a large optical cross-section — that is, an ability to emit light that dramatically exceeds its physical size — it can shed a lot of heat energy, making for a passive cooling system.

“This research opens up a new way to manipulate the flow of light, and could enable new technologies in light sensing and solar energy conversion,” Yu says.

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

Extraordinarily Large Optical Cross Section for Localized Single Nanoresonator by Ming Zhou, Lei Shi, Jian Zi, and Zongfu Yu. Phys. Rev. Lett. 115, 023903  DOI: http://dx.doi.org/10.1103/PhysRevLett.115.023903 Published 10 July 2015

This paper is behind a paywall.

Cellulose Nanofibrillated Fiber Based Transistors from the University of Wisconsin-Madison

There’s a team of researchers at the University of Wisconsin-Madison working to substitute silicon used in computer chips with cellulose derived from wood (my May 27, 2015 posting). Their latest effort, featuring mobile electronics, is described in a July 1, 2015 news item on Azonano,

A report published by the U.S. Environmental Protection Agency in 2012 showed that about 152 million mobile devices are discarded every year, of which only 10 percent is recycled — a legacy of waste that consumes a tremendous amount of natural resources and produces a lot of trash made from expensive and non-biodegradable materials like highly purified silicon.

Now researchers from the University of Wisconsin-Madison have come up with a new solution to alleviate the environmental burden of discarded electronics. They have demonstrated the feasibility of making microwave biodegradable thin-film transistors from a transparent, flexible biodegradable substrate made from inexpensive wood, called cellulose nanofibrillated fiber (CNF). This work opens the door for green, low-cost, portable electronic devices in future.

A June 30, 2015 American Institute of Physics news release by Zhengzheng Zhang, which originated the news item, describes the research in more detail,

“We found that cellulose nanofibrillated fiber based transistors exhibit superior performance as that of conventional silicon-based transistors,” said Zhenqiang Ma, the team leader and a professor of electrical and computer engineering at the UW-Madison. “And the bio-based transistors are so safe that you can put them in the forest, and fungus will quickly degrade them. They become as safe as fertilizer.”

Nowadays, the majority of portable electronics are built on non-renewable, non-biodegradable materials such as silicon wafers, which are highly purified, expensive and rigid substrates, but cellulose nanofibrillated fiber films have the potential to replace silicon wafers as electronic substrates in environmental friendly, low-cost, portable gadgets or devices of the future.

Cellulose nanofibrillated fiber is a sustainable, strong, transparent nanomaterial made from wood. Compared to other polymers like plastics, the wood nanomaterial is biocompatible and has relatively low thermal expansion coefficient, which means the material won’t change shape as the temperature changes. All these superior properties make cellulose nanofibril an outstanding candidate for making portable green electronics.

To create high-performance devices, Ma’s team employed silicon nanomembranes as the active material in the transistor — pieces of ultra-thin films (thinner than a human hair) peeled from the bulk crystal and then transferred and glued onto the cellulose nanofibrill substrate to create a flexible, biodegradable and transparent silicon transistor.To create high-performance devices, Ma’s team employed silicon nanomembranes as the active material in the transistor — pieces of ultra-thin films (thinner than a human hair) peeled from the bulk crystal and then transferred and glued onto the cellulose nanofibrill substrate to create a flexible, biodegradable and transparent silicon transistor.

But to make portable electronics, the biodegradable transistor needed to be able to operate at microwave frequencies, which is the working range of most wireless devices. The researchers thus conducted a series of experiments such as measuring the current-voltage characteristics to study the device’s functional performance, which finally showed the biodegradable transistor has superior microwave-frequency operation capabilities comparable to existing semiconductor transistors.

“Biodegradable electronics provide a new solution for environmental problems brought by consumers’ pursuit of quickly upgraded portable devices,” said Ma. “It can be anticipated that future electronic chips and portable devices will be much greener and cheaper than that of today.”

Next, Ma and colleagues plan to develop more complicated circuit system based on the biodegradable transistors.

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

Microwave flexible transistors on cellulose nanofibrillated fiber substrates by Jung-Hun Seo, Tzu-Hsuan Chang, Jaeseong Lee, Ronald Sabo, Weidong Zhou, Zhiyong Cai, Shaoqin Gong, and Zhenqiang Ma.  Applied Physics Letters, Volume 106, Issue 26 or  Appl. Phys. Lett. 106, 262101 (2015); http://dx.doi.org/10.1063/1.4921077

This is an open access paper.

Your tires generate energy that can be harvested

One day, this new work from the University of Wisconsin-Madison could help cut gas expenditures for your car and other motorized vehicles dependent on fossil fuels. A June 29, 2015 news item on Nanowerk describes the research (Note: A link has been removed),

A group of University of Wisconsin-Madison engineers and a collaborator from China have developed a nanogenerator that harvests energy from a car’s rolling tire friction.

An innovative method of reusing energy, the nanogenerator ultimately could provide automobile manufacturers a new way to squeeze greater efficiency out of their vehicles.

The researchers reported their development, which is the first of its kind, in a paper published May 6, 2015, in the journal Nano Energy (“Single-electrode triboelectric nanogenerator for scavenging friction energy from rolling tires”).

A June 29, 2015 University of Wisconsin-Madison news release (also on EurekAlert), which originated the news item, provides more details (Note: Links have been removed),

Xudong Wang, the Harvey D. Spangler fellow and an associate professor of materials science and engineering at UW-Madison, and his PhD student Yanchao Mao have been working on this device for about a year.

The nanogenerator relies on the triboelectric effect to harness energy from the changing electric potential between the pavement and a vehicle’s wheels. The triboelectric effect is the electric charge that results from the contact or rubbing together of two dissimilar objects.

Wang says the nanogenerator provides an excellent way to take advantage of energy that is usually lost due to friction.

“The friction between the tire and the ground consumes about 10 percent of a vehicle’s fuel,” he says. “That energy is wasted. So if we can convert that energy, it could give us very good improvement in fuel efficiency.”

The nanogenerator relies on an electrode integrated into a segment of the tire. When this part of the tire surface comes into contact with the ground, the friction between those two surfaces ultimately produces an electrical charge-a type of contact electrification known as the triboelectric effect.

During initial trials, Wang and his colleagues used a toy car with LED lights to demonstrate the concept. They attached an electrode to the wheels of the car, and as it rolled across the ground, the LED lights flashed on and off. The movement of electrons caused by friction was able to generate enough energy to power the lights, supporting the idea that energy lost to friction can actually be collected and reused.

“Regardless of the energy being wasted, we can reclaim it, and this makes things more efficient,” Wang says. “I think that’s the most exciting part of this, and is something I’m always looking for: how to save the energy from consumption.”

The researchers also determined that the amount of energy harnessed is directly related to the weight of a car, as well as its speed. Therefore the amount of energy saved can vary depending on the vehicle-but Wang estimates about a 10-percent increase in the average vehicle’s gas mileage given 50-percent friction energy conversion efficiency.

“There’s big potential with this type of energy,” Wang says. “I think the impact could be huge.”

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

Single-electrode triboelectric nanogenerator for scavenging friction energy from rolling tires by Yanchao Mao, Dalong Geng, Erjun Liang, & Xudong Wang. Nano Energy Volume 15, July 2015, Pages 227–234 doi:10.1016/j.nanoen.2015.04.026

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.

Tiny, electrically conductive 3D-printed chair made from cellulose

Sweden’s Chalmers University of Technology researchers have just announced that they’ve printed a very small 3D chair with electrical properties using cellulose nanomaterials. From a June 17, 2015 news item on Nanowerk,

A group of researchers at Chalmers University of Technology have managed to print and dry three-dimensional objects made entirely by cellulose for the first time with the help of a 3D-bioprinter. They also added carbon nanotubes to create electrically conductive material. The effect is that cellulose and other raw material based on wood will be able to compete with fossil-based plastics and metals in the on-going additive manufacturing revolution, which started with the introduction of the 3D-printer.

Here’s the 3D-printed chair,

The tiny chair made of cellulose is a demonstrational object, printed using the 3D bioprinter at Chalmers University of Technology. Photo: Peter Widing

The tiny chair made of cellulose is a demonstrational object, printed using the 3D bioprinter at Chalmers University of Technology. Photo: Peter Widing

A June 17, 2015 Chalmers University of Technology press release (also on EurekAlert*), which originated the news item, describes the problem with printing from cellulose nanomaterials and how it was solved,

The difficulty using cellulose in additive manufacturing is that cellulose does not melt when heated. Therefore, the 3D printers and processes designed for printing plastics and metals cannot be used for materials like cellulose. The Chalmers researchers solved this problem by mixing cellulose nanofibrils in a hydrogel consisting of 95-99 percent water. The gel could then in turn be dispensed with high fidelity into the researchers’ 3D bioprinter, which was earlier used to produce scaffolds for growing cells, where the end application is patient-specific implants.

The next challenge was to dry the printed gel-like objects without them losing their three-dimensional shape.

“The drying process is critical,” Paul Gatenholm explains. “We have developed a process in which we freeze the objects and remove the water by different means as to control the shape of the dry objects. It is also possible to let the structure collapse in one direction, creating thin films.”

Furthermore, the cellulose gel was mixed with carbon nanotubes to create electrically conductive ink after drying. Carbon nanotubes conduct electricity, and another project at Wallenberg Wood Science Center aims at developing carbon nanotubes using wood.

Using the two gels together, one conductive and one non-conductive, and controlling the drying process, the researchers produced three-dimensional circuits, where the resolution increased significantly upon drying.

The two gels together provide a basis for the possible development of a wide range of products made by cellulose with in-built electric currents.

“Potential applications range from sensors integrated with packaging, to textiles that convert body heat to electricity, and wound dressings that can communicate with healthcare workers,” says Paul Gatenholm. “Our research group now moves on with the next challenge, to use all wood biopolymers, besides cellulose.”

The research findings are presented this week at the conference New Materials From Trees that takes place in Stockholm, Sweden, June 15-17 [2015].

The research team members are Ida Henriksson, Cristina de la Pena, Karl Håkansson, Volodymyr Kuzmenko and Paul Gatenholm at Chalmers University of Technology.

This research reminds me of another effort, a computer chip fashioned of cellulose nanofibrils (CNF) from the University of Wisconsin-Madison (mentioned in my May 27, 2015 post).

* EurekAlert link added June 18, 2015.

Wood chip/computer chip, a cellulose nanofibril development

I imagine researchers at the University of Wisconsin-Madison and the US Department of Agriculture Forest Products Laboratory (FPL) are hoping they have managed to create a wood-based computer chip that can be commercialized in the near future. From a May 26, 2015 news item on ScienceDaily,

Portable electronics — typically made of non-renewable, non-biodegradable and potentially toxic materials — are discarded at an alarming rate in consumers’ pursuit of the next best electronic gadget.

In an effort to alleviate the environmental burden of electronic devices, a team of University of Wisconsin-Madison researchers has collaborated with researchers in the Madison-based U.S. Department of Agriculture Forest Products Laboratory (FPL) to develop a surprising solution: a semiconductor chip made almost entirely of wood.

The research team, led by UW-Madison electrical and computer engineering professor Zhenqiang “Jack” Ma, described the new device in a paper published today (May 26, 2015) by the journal Nature Communications. The paper demonstrates the feasibility of replacing the substrate, or support layer, of a computer chip, with cellulose nanofibril (CNF), a flexible, biodegradable material made from wood.

Here’s what the wood computer chip looks like,

A cellulose nanofibril (CNF) computer chip rests on a leaf. Photo: Yei Hwan Jung, Wisconsin Nano Engineering Device Laboratory

A cellulose nanofibril (CNF) computer chip rests on a leaf. Photo: Yei Hwan Jung, Wisconsin Nano Engineering Device Laboratory Courtesy University of Wisconsin-Madison

A May 25, 2015 University of Wisconsin-Madison news release by John Steeno, which originated the news item, provides more details,

“The majority of material in a chip is support. We only use less than a couple of micrometers for everything else,” Ma says. “Now the chips are so safe you can put them in the forest and fungus will degrade it. They become as safe as fertilizer.”

Zhiyong Cai, project leader for an engineering composite science research group at FPL, has been developing sustainable nanomaterials since 2009.

“If you take a big tree and cut it down to the individual fiber, the most common product is paper. The dimension of the fiber is in the micron stage,” Cai says. “But what if we could break it down further to the nano scale? At that scale you can make this material, very strong and transparent CNF paper.”

Working with Shaoqin “Sarah” Gong, a UW-Madison professor of biomedical engineering, Cai’s group addressed two key barriers to using wood-derived materials in an electronics setting: surface smoothness and thermal expansion.

“You don’t want it to expand or shrink too much. Wood is a natural hydroscopic material and could attract moisture from the air and expand,” Cai says. “With an epoxy coating on the surface of the CNF, we solved both the surface smoothness and the moisture barrier.”

Gong and her students also have been studying bio-based polymers for more than a decade. CNF offers many benefits over current chip substrates, she says.

“The advantage of CNF over other polymers is that it’s a bio-based material and most other polymers are petroleum-based polymers. Bio-based materials are sustainable, bio-compatible and biodegradable,” Gong says. “And, compared to other polymers, CNF actually has a relatively low thermal expansion coefficient.”

The group’s work also demonstrates a more environmentally friendly process that showed performance similar to existing chips. The majority of today’s wireless devices use gallium arsenide-based microwave chips due to their superior high-frequency operation and power handling capabilities. However, gallium arsenide can be environmentally toxic, particularly in the massive quantities of discarded wireless electronics.

Yei Hwan Jung, a graduate student in electrical and computer engineering and a co-author of the paper, says the new process greatly reduces the use of such expensive and potentially toxic material.

“I’ve made 1,500 gallium arsenide transistors in a 5-by-6 millimeter chip. Typically for a microwave chip that size, there are only eight to 40 transistors. The rest of the area is just wasted,” he says. “We take our design and put it on CNF using deterministic assembly technique, then we can put it wherever we want and make a completely functional circuit with performance comparable to existing chips.”

While the biodegradability of these materials will have a positive impact on the environment, Ma says the flexibility of the technology can lead to widespread adoption of these electronic chips.

“Mass-producing current semiconductor chips is so cheap, and it may take time for the industry to adapt to our design,” he says. “But flexible electronics are the future, and we think we’re going to be well ahead of the curve.”

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

High-performance green flexible electronics based on biodegradable cellulose nanofibril paper by Yei Hwan Jung, Tzu-Hsuan Chang, Huilong Zhang, Chunhua Yao, Qifeng Zheng, Vina W. Yang, Hongyi Mi, Munho Kim,    Sang June Cho, Dong-Wook Park, Hao Jiang, Juhwan Lee,    Yijie Qiu, Weidong Zhou, Zhiyong Cai, Shaoqin Gong, & Zhenqiang Ma. Nature Communications 6, Article number: 7170 doi:10.1038/ncomms8170 Published 26 May 2015

This paper is open access.

US Dept. of Agriculture awards $3.8M for nanotechnology research grants

I wonder just how much funding the US Dept. of Agriculture (USDA) is devoting to nanotechnology this year (2015). I first came across an announcement of $23M in the body of a news item about Zinkicide (my April 7, 2015 posting),

Found in Florida orchards in 2005, a citrus canker, citrus greening, poses a serious threat to the US state’s fruit industry. An April 2, 2105 news item on phys.org describes a possible solution to the problem,

Since it was discovered in South Florida in 2005, the plague of citrus greening has spread to nearly every grove in the state, stoking fears among growers that the $10.7 billion-a-year industry may someday disappear.

Now the U.S. Department of Agriculture has awarded the University of Florida a $4.6 million grant aimed at testing a potential new weapon in the fight against citrus greening: Zinkicide, a bactericide invented by a nanoparticle researcher at the University of Central Florida.

An April 29, 2015 article by Diego Flammini for Farm.com describes the latest USDA nanotechnology funding announcement,

In an effort to increase America’s food security, nutrition, food safety and environmental protection, the United States Department of Agriculture’s (USDA) National Institute of Food and Agriculture (NIFA) announced $3.8 million in nanotechnology research grants.

Flammini lists three of the eight recipients,

University of Georgia
With $496,192, the research team will develop different sensors that are able to detect fungal pathogens in crops. The project will also develop a smartphone app for farmers to have so they can access their information whenever necessary.

Rutgers University
The school will use its $450,000 to conduct a nationwide survey about nanotechnology and gauge consumer beliefs about it and its relationship to health. Among the specifics it will touch on is the use of visuals to communicate nanotechnology.

University of Massachusetts
The researchers will concentrate their $444,200 on developing a platform to detect pathogens in food that is better than the current methods.

A full list of the recipients can be found in the April 27, 2015 USDA news release featuring the $3.8M in awards,

  • The University of Georgia, Athens, Ga., $496,192
  • University of Iowa, Iowa City, Iowa., $496,180
  • University of Kentucky Research Foundation, Lexington, Ky., $450,000
  • University of Massachusetts, Amherst, Mass., $444,200
  • North Dakota State University, Fargo, N.D., $149,714
  • Rutgers University, New Brunswick. N.J., $450,000
  • Pennsylvania State University, University Park, University Park, Pa., $447,788
  • West Virginia University, Morgantown, W. Va., $496,168
  • University of Wisconsin-Madison, Madison, Wis., $450,100

You can find more details about the awards in this leaflet featuring the USDA project descriptions for the eight recipients.