Tag Archives: Guang Yao

Harvesting bioenergy to cure wounds and control weight

I’m always a sucker for bioenergy harvesting stories but this is the first time I’ve seen research on the topic which combines weight control with wound healing. From a January 17, 2019 news item on Nanowerk,


Although electrical stimulation has therapeutic potential for various disorders and conditions, ungainly power sources have hampered practical applications. Now bioengineers have developed implantable and wearable nanogenerators from special materials that create electrical pulses when compressed by body motions. The pulses controlled weight gain and enhanced healing of skin wounds in rat models.

The work was performed by a research team led by Xudong Wang, Ph.D., Professor of Material Sciences and Engineering, College of Engineering, University of Wisconsin-Madison, and supported by the [US Dept. of Health, National Institutes of Health] National Institute of Biomedical Imaging and Bioengineering (NIBIB).

A January 17, 2019 NIBIB news release, which originated the news item, provides more technical information (Note: Links have been removed),

The researchers used what are known as piezoelectric and dielectric materials, including ceramics and crystals, which have a special property of creating an electrical charge in response to mechanical stress.

“Wang and colleagues have engineered solutions to a number of technical hurdles to create piezoelectric and dielectric materials that are compatible with body tissues and can generate a reliable, self-sufficient power supply. Their meticulous work has enabled a simple and elegant technology that offers the possibility of developing electrical stimulation therapies for a number of major diseases that currently lack adequate treatments,” explained David Rampulla, Ph.D., director of the Program in Biomaterials and Biomolecular Constructs at NIBIB

Shedding weight by curbing appetite

Worldwide, more than 700 million people — over 100 million of them children — are obese, causing health problems such as cardiovascular disease, diabetes, kidney disease, and certain cancers. In 2015 approximately four million people died of obesity-related causes1.

To address this crisis, Wang and his colleagues developed a vagal nerve stimulator (VNS) that dramatically improves appetite suppression through electrical stimulation of the vagus nerve. The approach is a promising one that has previously not proven practical because patients must carry bulky battery packs that require proper programming, and frequent recharging

The VNS consists of a small patch, about the size of a fingernail, which carries tiny devices called nanogenerators. Minimally invasive surgery was used to attach the VNS to the stomachs of rats. The rat’s stomach movements resulted in the delivery of gentle electrical pulses to the vagus nerve, which links the brain to the stomach. With the VNS, when the stomach moved in response to eating, the electric signal told the brain that the stomach was full, even if only a small amount of food was consumed.

The device curbed the rat’s appetite and reduced body weight by a remarkable 40 percent. “The stimulation is a natural response to regulate food intake, so there are no unwanted side effects,” explained Wang. When the device was removed the rats resumed their normal eating patterns and their weight returned to pre-treatment levels.

“Given the simplicity and effectiveness of the system, coupled with the fact that the effect is reversible and carries no side-effects, we are now planning testing in larger animals with the hope of eventually moving into human trials,” said Wang.

Accelerating wound healing

In another NIBIB-funded study in a rat experimental model, the researchers used their nanogenerator technology to determine whether electrical stimulation would accelerate healing of wounds on the skin surface.

For this experiment, a band of nanogenerators was placed around the rat’s chest, where the expansion from breathing created a mild electric field. Small electrodes in a bandage-like device were placed over skin wounds on the rat’s back, where they directed the electric field to cover the wound area.

The technique reduced healing times to just three days compared with nearly two weeks for the normal healing process.

Similar to the case with appetite suppression, it was known that electricity could enhance wound healing, but the devices that had been developed were large and impractical. The nanogenerator-powered bandage is completely non-invasive and produced a mild electric field that is similar to electrical activity detected in the normal wound-healing process.

The researchers observed electrical activation of normal cellular healing processes that included the movement of healthy skin fibroblasts into the wound, accompanied by the release of biochemical factors that promote the growth of the fibroblasts and other cell types that expand to repair the wound space.

“The dramatic decrease in healing time was surprising,” said Wang, “We now plan to test the device on pigs because their skin is very similar to humans.” 

The team believes the simplicity of the electric bandage will help move the technology to human trials quickly. In addition, Wang explained that the fabrication of the device is very inexpensive and a product for human use would cost about the same as a normal bandage.

The experiments on appetite suppression were reported in the December issue of Nature Communications2. The wound-healing studies were reported in the December issue of ACS Nano3. Both studies were supported by grant EB021336 from the National Institute of Biomedical Imaging and Bioengineering, and grant CA014520 from the National Cancer Institute.

Here are links to and citations for the papers,

Effective weight control via an implanted self-powered vagus nerve stimulation device by Guang Yao, Lei Kang, Jun Li, Yin Long, Hao Wei, Carolina A. Ferreira, Justin J. Jeffery, Yuan Lin, Weibo Cai & Xudong Wang. Nature Communications volume 9, Article number: 5349 (2018) DOI: https://doi.org/10.1038/s41467-018-07764-z Published 17 December 2018

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, 2018, 12 (12), pp 12533–12540 DOI: 10.1021/acsnano.8b07038 Publication Date (Web): November 29, 2018

Copyright © 2018 American Chemical Society

Both papers are open access.

Bandage with nanogenerator promotes healing

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.