University of California Berkeley Engineers Create Energy-Scavenging Nanofibers that Could One Day Be Woven Into Clothing and Textiles

fiber nanogenerator

Shown is a fiber nanogenerator on a plastic substrate created by UC Berkeley scientists. The nanofibers can convert energy from mechanical stresses and into electricity, and could one day be used to create clothing that can power small electronics. (Chieh Chang, UC Berkeley)

















In research that gives literal meaning to the term “power suit,” University of California, Berkeley, engineers have created energy-scavenging nanofibers that could one day be woven into clothing and textiles.
These nano-sized generators have “piezoelectric” properties that allow them to convert into electricity the energy created through mechanical stress, stretches and twists.
“This technology could eventually lead to wearable ‘smart clothes’ that can power hand-held electronics through ordinary body movements,” said Liwei Lin, UC Berkeley professor of mechanical engineering and head of the international research team that developed the fiber nanogenerators.
Because the nanofibers are made from organic polyvinylidene fluoride, or PVDF, they are flexible and relatively easy and cheap to manufacture.
Although they are still working out the exact calculations, the researchers noted that more vigorous movements, such as the kind one would create while dancing the electric boogaloo, should theoretically generate more power. “And because the nanofibers are so small, we could weave them right into clothes with no perceptible change in comfort for the user,” said Lin, who is also co-director of the Berkeley Sensor and Actuator Center at UC Berkeley.
The fiber nanogenerators are described in this month’s issue of Nano Letters, a peer-reviewed journal published by the American Chemical Society.
The goal of harvesting energy from mechanical movements through wearable nanogenerators is not new. Other research teams have previously made nanogenerators out of inorganic semiconducting materials, such as zinc oxide or barium titanate. “Inorganic nanogenerators — in contrast to the organic nanogenerators we created — are more brittle and harder to grow in significant quantities,” Lin said.
The tiny nanogenerators have diameters as small as 500 nanometers, or about 100 times thinner than a human hair and one-tenth the width of common cloth fibers. The researchers repeatedly tugged and tweaked the nanofibers, generating electrical outputs ranging from 5 to 30 millivolts and 0.5 to 3 nanoamps.
Furthermore, the researchers report no noticeable degradation after stretching and releasing the nanofibers for 100 minutes at a frequency of 0.5 hertz (cycles per second).
Lin’s team at UC Berkeley pioneered the near-field electrospinning technique used to create and position the polymeric nanogenerators 50 micrometers apart in a grid pattern. The technology enables greater control of the placement of the nanofibers onto a surface, allowing researchers to properly align the fiber nanogenerators so that positive and negative poles are on opposite ends, similar to the poles on a battery.
Without this control, the researchers explained, the negative and positive poles might cancel each other out and reducing energy efficiency.
The researchers demonstrated energy conversion efficiencies as high as 21.8 percent, with an average of 12.5 percent.
“Surprisingly, the energy efficiency ratings of the nanofibers are much greater than the 0.5 to 4 percent achieved in typical power generators made from experimental piezoelectric PVDF thin films, and the 6.8 percent in nanogenerators made from zinc oxide fine wires,” said the study’s lead author, Chieh Chang, who conducted the experiments while he was a graduate student in mechanical engineering at UC Berkeley.
“We think the efficiency likely could be raised further,” Lin said. “For our preliminary results, we see a trend that the smaller the fiber we have, the better the energy efficiency. We don’t know what the limit is.”
Other co-authors of the study are Yiin-Kuen Fuh, a UC Berkeley graduate student in mechanical engineering; Van H. Tran, a graduate student at the Technische Universität München (Technical University of Munich) in Germany; and Junbo Wang, a researcher at the Institute of Electronics at the Chinese Academy of Sciences in Beijing, China.
The National Science Foundation and the Defense Advanced Research Projects Agency helped support this research.

UCLA Develops 3-Dimensional Batteries and Demonstrates Fuel Cells Powered by Sugar

Bruce Dunn is a Professor of Materials Science at UCLA’s Henry Samueli School of Engineering and Applied Science. Follow him around UCLA’s campus as he discusses 3-dimensional batteries and demonstrates fuel cells powered by sugar.
Ever since the beginning of the age of “electrification,” scientists and engineers have struggled with a fundamental problem: How do you store electricity until you need it?
One way is in a battery, but batteries are too heavy and expensive, and they are so large they dictate the size of many things that use them.
Today’s batteries are two-dimensional, with a layer of anode, a layer of cathode and a layer of electrolyte. Dunn is working in the third dimension, which consists of “an array of pins that are all sort of sticking up in the air. So the area they take up is pretty small, but they go up into a third dimension,” providing more storage space for the chemical energy that will convert to electrical energy.
Dunn says he can build batteries so small they will fit on a semiconductor chip and power incredibly small devices. With these and many other projects, it’s clear that wherever and however we get our energy in the future, UCLA will be in the forefront of the science — and that’s the kind of power we can all enjoy.

Purdue Magnetic “Ferropaper” for Low Cost Micromotors, Surgical Instruments, Cell Tweezers and Miniature Speakers

Researchers at Purdue University have created a magnetic “ferropaper” that might be used to make low-cost “micromotors” for surgical instruments, tiny tweezers to study cells and miniature speakers.

The material is made by impregnating ordinary paper – even newsprint – with a mixture of mineral oil and “magnetic nanoparticles” of iron oxide. The nanoparticle-laden paper can then be moved using a magnetic field.

“Paper is a porous matrix, so you can load a lot of this material into it,” said Babak Ziaie, a professor of electrical and computer engineering and biomedical engineering.

Image Credit: Purdue University

The new technique represents a low-cost way to make small stereo speakers, miniature robots or motors for a variety of potential applications, including tweezers to manipulate cells and flexible fingers for minimally invasive surgery.
“Because paper is very soft it won’t damage cells or tissue,” Ziaie said. “It is very inexpensive to make. You put a droplet on a piece of paper, and that is your actuator, or motor.”
Once saturated with this “ferrofluid” mixture, the paper is coated with a biocompatible plastic film, which makes it water resistant, prevents the fluid from evaporating and improves mechanical properties such as strength, stiffness and elasticity.
Findings will be detailed in a research paper being presented during the 23rd IEEE International Conference on Micro Electro Mechanical Systems on Jan. 24-28 in Hong Kong. The paper was written by Ziaie, electrical engineering doctoral student Pinghung Wei and physics doctoral student Zhenwen Ding.
Because the technique is inexpensive and doesn’t require specialized laboratory facilities, it could be used in community colleges and high schools to teach about micro robots and other engineering and scientific principles, Ziaie said.
The magnetic particles, which are commercially available, have a diameter of about 10 nanometers, or billionths of a meter, which is roughly 1/10,000th the width of a human hair. Ferro is short for ferrous, or related to iron.
“You wouldn’t have to use nanoparticles, but they are easier and cheaper to manufacture than larger-size particles,” Ziaie said. “They are commercially available at very low cost.”
The researchers used an instrument called a field-emission scanning electron microscope to study how well the nanoparticle mixture impregnates certain types of paper.
“All types of paper can be used, but newspaper and soft tissue paper are especially suitable because they have good porosity,” Ziaie said.
The researchers fashioned the material into a small cantilever, a structure resembling a diving board that can be moved or caused to vibrate by applying a magnetic field.
“Cantilever actuators are very common, but usually they are made from silicon, which is expensive and requires special cleanroom facilities to manufacture,” Ziaie said. “So using the ferropaper could be a very inexpensive, simple alternative. This is like 100 times cheaper than the silicon devices now available.”
The researchers also have experimented with other shapes and structures resembling Origami to study more complicated movements.
The research is based at the Birck Nanotechnology Center in Purdue’s Discovery Park.
Writer: Emil Venere, (765) 494-4709, venere@purdue.edu

Neah Power System Acquires CyVolt Energy Systems, Plans Hybrid Fuel Cell Product Introduction within 6 Months

Neah Power Systems, Inc., a company developing fuel cell based renewable energy solutions, reported that it has signed documents with CyVolt Energy Systems to acquire all of its technology and assets. The cost of the acquisition would be covered by the company’s recently announced financing that management plans to use to acquire businesses that are expected to provide positive cash flows in the near term.
Dr. Chris D’Couto, President and CEO of Neah Power Systems, said, “Neah’s goals, as part of the recently announced funding, is to complete strategic acquisitions that complement Neah’s technology and meet our target of having commercially available products within the next 6 months. CyVolt meets these high standards.”
Neah intends to introduce the product, a hybrid fuel cell technology that recharges industry-standard lithium ion batteries, to the retail market within four to six months. Lithium ion batteries are the most common form of battery used in portable electronics. The product will produce ongoing power by “hot-swapping” additional fuel via cartridges or refills, thereby eliminating dependence on access to the electrical grid.
CyVolt Energy Systems is a Cleantech company developing fuel cell based portable power products for the consumer and military electronics market. CyVolt has developed a renewable fuel cell technology with the potential of significantly reducing development and downstream manufacturing costs. www.cyvolt.com
 Neah Power Systems, Inc. (OTCBB: NPWZ) is developing long-lasting, efficient and safe power solutions for the military, industrial and consumer applications, Neah uses a unique, patented, silicon-based design for its micro fuel cells that enable higher power densities, lower cost and compact form-factors. The company’s micro fuel cell system can run in aerobic and anaerobic modes. The company is developing energy generation and storage solutions based on its patented technology. Further company information can be found at www.neahpower.com.

Home Cancer Test Like Home Pregnancy Test Could Soon Be a Reality Thanks to University of Missouri Research

What if it were possible to go to the store and buy a kit to quickly and accurately diagnose cancer, similar to a pregnancy test? A University of Missouri researcher is developing a tiny sensor, known as an acoustic resonant sensor, that is smaller than a human hair and could test bodily fluids for a variety of diseases, including breast and prostate cancers.
“Many disease-related substances in liquids are not easily tracked,” said Jae Kwon, assistant professor of electrical and computer engineering at MU. “In a liquid environment, most sensors experience a significant loss of signal quality, but by using highly sensitive, low-signal-loss acoustic resonant sensors in a liquid, these substances can be effectively and quickly detected — a brand-new concept that will result in a noninvasive approach for breast cancer detection.”
Kwon’s real-time, special acoustic resonant sensor uses micro/nanoelectromechanical systems (M/NEMS), which are tiny devices smaller than the diameter of a human hair, to directly detect diseases in body fluids.
 The sensor doesn’t require bulky data reading or analyzing equipment and can be integrated with equally small circuits, creating the potential for small stand-alone disease-screening systems. Kwon’s sensor also produces rapid, almost immediate results that could reduce patient anxiety often felt after waiting for other detection methods, such as biopsies, which can take several days or weeks before results are known.
“Our ultimate goal is to produce a device that will simply and quickly diagnose multiple specific diseases, and eventually be used to create ‘point of care’ systems, which are services provided to patients at their bedsides,” Kwon said. “The sensor has strong commercial potential to be manifested as simple home kits for easy, rapid and accurate diagnosis of various diseases, such as breast cancer and prostate cancer.”
Last January, Kwon was awarded a $400,000, five-year National Science Foundation CAREER Award to continue his effort on this sensor research. The CAREER award is the NSF’s most prestigious award in support of junior faculty members who exemplify the role of teacher-scholars through outstanding research, excellent teaching, and the integration of education and research. Kwon’s sensor research has been published in the IEEE International Conference on Solid-state, Sensors, Actuators and Microsystems and the IEEE Conference on Sensors.