The piezoelectric wafer at left shows the crystalline structure of the middle...
The piezoelectric wafer at left shows the crystalline structure of the middle layer of lysine. On the right the wafer easily flexes for biocompatibility and to induce the lysine crystal to create an electrical output. Scale is centimeters.
Source: Xudong Wang, University of Wisconsin-Madison

Using muscle power for healing

Bioengineers at the University of Wisconsin's Department of Materials Science and Engineering have developed biocompatible generators that create electrical pulses when compressed by body motions. The generators are made up of self-assembling "piezoelectric wafers" which can be made rapidly and inexpensively to enable broad use of muscle-powered electromechanical therapies.

Piezoelectric materials such as ceramics and crystals have a special property of creating an electrical charge in response to mechanical stress.They are used in numerous devices including ultrasound transducers, vibration sensors, and cell phones. In medicine, electrostimulation using piezoelectric devices has been shown to be beneficial for accelerating the healing of wounds and bone fractures, maintaining muscle tone in stroke victims, and reducing chronic pain. However, the lack of biocompatibility — resulting in stiffness and toxicity — has stalled progress in the field.

The bioengineers have developed implantable piezoelectric therapeutic devices. The wafer-thin, flexible devices take advantage of the fact that non-rigid, nontoxic biological materials such as silk, collagen, and amino acids also have piezoelectric properties.

The team, led by Xudong Wang, Ph.D., professor of Materials Science and Engineering, created a method for self-assembly of small patch-like constructs that use the amino acid lysine as the piezoelectric generator. The self-assembly process incorporates a biocompatible polymer shell that surrounds the lysine as the polymer/lysine solution evaporates. The chemical interaction between the inner layer of lysine and the polymer coating are critical for orienting the lysine into the crystal structure necessary for it to produce electric current when flexed.

This work is an outstanding example of using the chemical properties of the materials to create a self-assembling product.

David Rampulla

"This work is an outstanding example of using the chemical properties of the materials to create a self-assembling product," explains David Rampulla, director of the Division of Discovery Science and Technology at the National Institute of Biomedical Imaging and Bioengineering, which supports the research. "The process used is rapid and inexpensive, making production of such wafers for therapeutic applications feasible. That the wafers are biodegradable opens the possibility for creating electrotherapies that could be used to accelerate healing of an injured bone or muscle, for example, and then degrade and disappear from the body."

The team did a number of tests of the properties of the piezoelectric wafers. Wafers were placed in the leg and chest of rats. The leg movements and chest movements compressed the piezoelectric wafers enough to create an electrical output. Blood tests that were done after the transplanted wafer dissolved in the rats showed normal levels of blood cells and other metabolites indicating there were no harmful effects from the dissolved device.

Wang stresses the simplicity of the team's elegant work that can turn muscle movements into potentially game-changing therapeutic approaches. "We believe the technology opens a vast array of possibilities including real-time sensing, accelerated healing of wounds and other types of injuries, and electrical stimulation to treat pain and other neurological disorders. Importantly, our rapid self-assembling technology dramatically reduces the cost of such devices, which has the potential to greatly expand the use of this very promising form of medical intervention."

Subscribe to our newsletter

Related articles

Bioelectronic implant could prevent opioid deaths

Bioelectronic implant could prevent opioid deaths

Researchers are developing a device that can sense the effects of a potentially fatal level of ingested opioids and deliver a life-saving dose of naloxone.

Converting human body motions into electricity

Converting human body motions into electricity

Bioengineers have invented a novel soft and flexible self-powered bioelectronic device that converts human body motions into electricity.

Glove and gaming make rehabilitation fun

Glove and gaming make rehabilitation fun

A new sensor material suitable for developing a rehabilitation glove.

Diabetology 4.0: emerging technologies for diabetes care

Diabetology 4.0: emerging technologies for diabetes care

This overview introduces smart insulin delivery systems and more innovations that help patients and doctors guide decision-making in diabetes care.

Immunotherapy response studied in body-on-a-chip models

Immunotherapy response studied in body-on-a-chip models

Clinicians are using patient-specific tumor 'organoid' models as a preclinical companion platform to better evaluate immunotherapy treatment for appendiceal cancer.

Self-aware materials for living structures

Self-aware materials for living structures

Researchers at University of Pittsburgh have developed a revolutionary scalable material that senses and powers itself.

Microfluidics: efficiently smuggling drugs into cells

Microfluidics: efficiently smuggling drugs into cells

Progressive Mechanoporation makes it possible to mechanically disrupt the membranes of cells for a short time period and let drugs or genes inside cells.

CRISPRoff offers unrivaled control of epigenetic inheritance

CRISPRoff offers unrivaled control of epigenetic inheritance

Scientists have figured out how to modify CRISPR’s basic architecture to extend its reach beyond the genome and into what’s known as the epigenome.

A conductive hydrogel for medical applications

A conductive hydrogel for medical applications

Researchers have developed a method to produce graphene-enhanced hydrogels with an excellent level of electrical conductivity.

Popular articles

Subscribe to Newsletter