Tag Archives: nanogenerators

Bandage with nanogenerator promotes healing

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This bandage not only heals wounds (on rats) much faster; it’s cheap, according to a November 29, 2018 news item on Nanowerk,

A new, low-cost wound dressing developed by University of Wisconsin-Madison engineers could dramatically speed up healing in a surprising way.

The method leverages energy generated from a patient’s own body motions to apply gentle electrical pulses at the site of an injury.

In rodent tests, the dressings reduced healing times to a mere three days compared to nearly two weeks for the normal healing process.

“We were surprised to see such a fast recovery rate,” says Xudong Wang, a professor of materials science and engineering at UW-Madison. “We suspected that the devices would produce some effect, but the magnitude was much more than we expected.”

A November 29, 2018 University of Wisconsin-Madison news release (also on EurekAlert) by Sam Million-Weaver, which originated the news item, expands on the theme,

Researchers have known for several decades that electricity can be beneficial for skin healing, but most electrotherapy units in use today require bulky electrical equipment and complicated wiring to deliver powerful jolts of electricity.

“Acute and chronic wounds represent a substantial burden in healthcare worldwide,” says collaborator Angela Gibson, professor of surgery at UW-Madison and a burn surgeon and director of wound healing services at UW Health. “The use of electrical stimulation in wound healing is uncommon.”

In contrast with existing methods, the new dressing is much more straightforward.

“Our device is as convenient as a bandage you put on your skin,” says Wang.

The new dressings consist of small electrodes for the injury site that are linked to a band holding energy-harvesting units called nanogenerators, which are looped around a wearer’s torso. The natural expansion and contraction of the wearer’s ribcage during breathing powers the nanogenerators, which deliver low-intensity electric pulses.

“The nature of these electrical pulses is similar to the way the body generates an internal electric field,” says Wang.

And, those low-power pulses won’t harm healthy tissue like traditional, high-power electrotherapy devices might.

In fact, the researchers showed that exposing cells to high-energy electrical pulses caused them to produce almost five times more reactive oxygen species — major risk factors for cancer and cellular aging — than did cells that were exposed to the nanogenerators.

Also a boon to healing: They determined that the low-power pulses boosted viability for a type of skin cell called fibroblasts, and exposure to the nanogenerator’s pulses encouraged fibroblasts to line up (a crucial step in wound healing) and produce more biochemical substances that promote tissue growth.

“These findings are very exciting,” says collaborator Weibo Cai, a professor of radiology at UW-Madison. “The detailed mechanisms will still need to be elucidated in future work.”

In that vein, the researchers aim to tease out precisely how the gentle pulses aid in healing. The scientists also plan to test the devices on pig skin, which closely mimics human tissue.

And, they are working to give the nanogenerators additional capabilities–tweaking their structure to allow for energy harvesting from small imperceptible twitches in the skin or the thrumming pulse of a heartbeat.

“The impressive results in this study represent an exciting new spin on electrical stimulation for many different wound types, given the simplicity of the design,” says Gibson, who will collaborate with the team to confirm the reproducibility of these results in human skin models.

If the team is successful, the devices could help solve a major challenge for modern medicine.

“We think our nanogenerator could be the most effective electrical stimulation approach for many therapeutic purposes,” says Wang.

And because the nanogenerators consist of relatively common materials, price won’t be an issue.

“I don’t think the cost will be much more than a regular bandage,” says Wang. “The device in itself is very simple and convenient to fabricate.”

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

Effective Wound Healing Enabled by Discrete Alternative Electric Fields from Wearable Nanogenerators by Yin Long, Hao Wei, Jun Li, Guang Yao, Bo Yu, Dalong Ni, Angela LF Gibson, Xiaoli Lan, Yadong Jiang, Weibo Cai, and Xudong Wang. ACS Nano, Article ASAP DOI: 10.1021/acsnano.8b07038 Publication Date (Web): November 29, 2018

Copyright © 2018 American Chemical Society

This paper is open access.

I assume it will be a while before there are human clinical trials.

Hyper stretchable nanogenerator

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There’s a lot of talk about flexibility, stretchability and bendability in electronics and the latest is coming from Korea. An April 13, 2015 Korea Advanced Institute for Science and Technology (KAIST) news release on EurekAlert describes the situation and the Korean scientists’ most recent research into stretchable electronics,

A research team led by Professor Keon Jae Lee of the Department of Materials Science and Engineering at the Korea Advanced Institute of Science and Technology (KAIST) has developed a hyper-stretchable elastic-composite energy harvesting device called a nanogenerator.

Flexible electronics have come into the market and are enabling new technologies like flexible displays in mobile phone, wearable electronics, and the Internet of Things (IoTs). However, is the degree of flexibility enough for most applications? For many flexible devices, elasticity is a very important issue. For example, wearable/biomedical devices and electronic skins (e-skins) should stretch to conform to arbitrarily curved surfaces and moving body parts such as joints, diaphragms, and tendons. They must be able to withstand the repeated and prolonged mechanical stresses of stretching. In particular, the development of elastic energy devices is regarded as critical to establish power supplies in stretchable applications. Although several researchers have explored diverse stretchable electronics, due to the absence of the appropriate device structures and correspondingly electrodes, researchers have not developed ultra-stretchable and fully-reversible energy conversion devices properly.

Recently, researchers from KAIST and Seoul National University (SNU) have collaborated and demonstrated a facile methodology to obtain a high-performance and hyper-stretchable elastic-composite generator (SEG) using very long silver nanowire-based stretchable electrodes. Their stretchable piezoelectric generator can harvest mechanical energy to produce high power output (~4 V) with large elasticity (~250%) and excellent durability (over 104 cycles). These noteworthy results were achieved by the non-destructive stress- relaxation ability of the unique electrodes as well as the good piezoelectricity of the device components. The new SEG can be applied to a wide-variety of wearable energy-harvesters to transduce biomechanical-stretching energy from the body (or machines) to electrical energy.

Professor Lee said, “This exciting approach introduces an ultra-stretchable piezoelectric generator. It can open avenues for power supplies in universal wearable and biomedical applications as well as self-powered ultra-stretchable electronics.”

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

A Hyper-Stretchable Elastic-Composite Energy Harvester by Chang Kyu Jeong, Jinhwan Lee, Seungyong Han, Jungho Ryu, Geon-Tae Hwang, Dae Yong Park, Jung Hwan Park, Seung Seob Lee, Mynghwan Byun, Seung Hwan Ko, and Keon Jae Lee. Advanced Materials DOI: 10.1002/adma.201500367 30 March 2015Full

This paper is behind a paywall.

The researchers have prepared a short video (22 secs. and silent),

Finger pinches today, heartbeats tomorrow and electricity forever

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Devices powered by energy generated and harvested from one’s own body have been of tremendous interest to me. Last year I mentioned some research in this area by Professor Zhong Lin Wang at Georgia Tech (Georgia Institute of Technology) in a July 12, 2010 posting. Well, Wang and his team recently announced that they have developed the first commercially viable nanogenerator. From the March 29, 2011 news item on Physorg.com,

After six years of intensive effort, scientists are reporting development of the first commercially viable nanogenerator, a flexible chip that can use body movements — a finger pinch now en route to a pulse beat in the future — to generate electricity. Speaking here today at the 241st National Meeting & Exposition of the American Chemical Society, they described boosting the device’s power output by thousands times and its voltage by 150 times to finally move it out of the lab and toward everyday life.

“This development represents a milestone toward producing portable electronics that can be powered by body movements without the use of batteries or electrical outlets,” said lead scientist Zhong Lin Wang, Ph.D. “Our nanogenerators are poised to change lives in the future. Their potential is only limited by one’s imagination.”

Here’s how it works  (from Kit Eaton’s article on Fast Company),

The trick used by Dr. Zhong Lin Wang’s team has been to utilize nanowires made of zinc oxide (ZnO). ZnO is a piezoelectric material–meaning it changes shape slightly when an electrical field is applied across it, or a current is generated when it’s flexed by an external force. By combining nanoscopic wires (each 500 times narrower than a human hair) of ZnO into a flexible bundle, the team found it could generate truly workable amounts of energy. The bundle is actually bonded to a flexible polymer slice, and in the experimental setup five pinky-nail-size nanogenerators were stacked up to create a power supply that can push out 1 micro Amp at about 3 volts. That doesn’t sound like a lot, but it was enough to power an LED and an LCD screen in a demonstration of the technology’s effectiveness.

Dexter Johnson at Nanoclast on the IEEE (Institute of Electrical Engineering and Electronics) website notes in his March 30, 2010 posting (http://spectrum.ieee.org/nanoclast/semiconductors/nanotechnology/powering-our-electronic-devices-with-nanogenerators-looks-more-feasible) that the nanogenerator’s commercial viability is dependent on work being done at the University of Illinois,

I would have happily chalked this story [about the nanogenerator] up to one more excellent job of getting nanomaterial research into the mainstream press, but because of recent work by Eric Pop and his colleagues at the University of Illinois’s Beckman Institute in reducing the energy consumed by electronic devices it seems a bit more intriguing now.

So low is the energy consumption of the electronics proposed by the University of Illinois research it is to the point where a mobile device may not need a battery but could possibly operate on the energy generated from piezoelectric-enabled nanogenerators contained within such devices like those proposed by Wang.

I have a suspicion it’s going to be a while before I will be wearing nanogenerators to harvest the electricity my body produces. Meanwhile, I have some questions about the possible uses for nanogenerators (from the Kit Eaton article),

The search for tiny power generator technology has slowly inched forward for years for good reason–there are a trillion medical and surveillance uses–not to mention countless consumer electronics applications– for a system that could grab electrical power from something nearby that’s moving even just a tiny bit. Imagine an implanted insulin pump, or a pacemaker that’s powered by the throbbing of the heart or blood vessels nearby (and then imagine the pacemaker powering the heart, which is powered by the pacemaker, and so on and so on….) and you see how useful such a system could be.

It’s the reference to surveillance that makes me a little uneasy.