Materials Science and Engineering Professor Xudong Wang is improving the electrical efficiency and biocompatibility of batteries and implantable electrostimulation devices for tissue repair.
When light hits the nacre of an oyster’s inner shell, variations in thickness create shimmering interference patterns, resulting in the lustrous glow of mother-of-pearl. Nacre is composed of thin, microscopic layers of calcium carbonate and soft proteins that function like brick and mortar, allowing the oyster’s shell to absorb the mechanical stresses of rolling along the ocean floor without fracturing.
UW-Madison Materials Science and Engineering Professor Xudong Wang recently developed strategies for 3D printing nacre-like structures in his laboratory that enhance a material’s capability to generate an electric charge when squeezed, stretched, or otherwise physically manipulated. The nacre-like composition also enhances the strength of the material, preventing shattering when subjected to mechanical impact. Wang’s invention, which is designed to be used as an implantable electrostimulation device to potentially repair damaged bone, strikes a balance between soft and hard composite materials to boost electrical efficiency and toughness.
“Creating thin layers in the microstructure can disperse the force subjected to the material, meaning that you can hit it hard without breaking it, while producing more electricity,” says Wang. “We may use this new material as artificial bones to produce localized electricity to stimulate tissue growth.”
The Wisconsin Alumni Research Foundation (WARF) recently patented his method to 3D-print ferroelectric materials with large-scale piezoelectricity, or the ability to polarize a material through mechanical stress.
Wang’s career, established in the early days of materials science engineering, focuses on developing applications that generate electricity from human movement. In another recent invention, he incorporated the amino acid glycine with Polyvinyl alcohol (PVA), a material designed to generate small electric charges in electrostimulation tissue scaffolds or to act as an energy source in implantable sensors.
Wang’s patents include transient, biodegradable electronics with longer duration battery power for potential use in cardiac pacemakers, defibrillators, and neurostimulators, as well as a wearable energy harvesting system which converts body movement into electrical power for use in therapeutic electrostimulation.
“I think the biggest challenge to the field of biocompatible piezoelectric materials is still energy conversion efficiency,”
“Our body has sufficient energy to serve as a perfect source of kinetic energy for electricity to power devices locally for healthcare monitoring and electrostimulation therapeutics.”
Xudong Wang
Wang’s group showed that the material with various amino acid additions can generate an appreciable voltage output in in vivo models, resolving a longstanding scalability issue.
“When we began, the field of materials science and engineering was focused on one-dimensional nanowires with biocompatible materials like zinc oxide or titanium dioxide,” Wang recounts. While Wang and his team tackled challenges associated with synthesizing materials, they recognized early on that incorporating three-dimensional structures could enhance scalability and functionality, broadening potential applications.
His lab also applies three-dimensional design to solar energy conversion. Wang explains, “We used a separate etching process to create complex, non-planar geometries that, in the case of the nanowires, increased surface area and interaction potential to convert sunlight into hydrogen fuel.”
Wang attributes his interest in the field to an early interest in exploring: “By the time I was an undergraduate, nanotechnology was an emerging field. I think I am lucky in part because I am always looking to find some area that may eventually turn into a real product.”
Through curiosity-driven approaches, Wang continues to bridge nature-inspired materials with real-world applications in energy conversion.