Trade.Information

Topic Name: Research team hopes Portable electricity, life-like prosthetics on the way

Category: Mechanical

Research persons: Pradeep Sharmas' Research Team

Location: University of Houston, United States

Details

The technology that makes a cell phone vibrate is the same technology that provides more natural movements to prosthetic limbs. A University of Houston research team is working on recreating and enhancing this technological effect, which, if successful, could result in better prosthetic movements and also provide instant electrical power for soldiers and others through the simple act of walking.

Pradeep Sharma, a UH mechanical engineering professor, is leading the team to create a “piezoelectric on steroids.” Piezoelectricity is the ability of some materials to generate an electric charge when placed under stress. This pioneering technology already is more useful than many people realize. Piezoelectrics are involved in everything from making an airbag deploy to how a lighter produces a flame.

Although piezoelectrics are naturally occurring, they have their limits. If an application requires a level of energy conversion not found in a naturally occurring piezoelectric, a composite consisting of piezoelectrics and non-piezoelectrics must be made. Sharma and his team are creating piezoelectrics from man-made materials that have no piezoelectric property.

“If you press on a piezoelectric, or apply mechanical force, it will produce a voltage,” Sharma said. “Or, if you apply a voltage or electrical force to it, the object will bend or change its shape.”

An engineered piezoelectric strip placed in the boot of a soldier would generate electricity and power the increasing number of devices that soldiers carry. The walking motion produces force or deformation of the strip, which generates electricity with every step. The highly customizable piezoelectrics also could enable the creation of prosthetics that come closer to offering both the flexibility and the strength of real limbs. Current prosthetic limbs face challenges in range and movement by the two types of naturally occurring piezoelectrics, ceramic and polymer.

“Ceramic piezoelectrics are very hard and brittle, and don’t allow for a lot of movement,” Sharma said. “They take a lot of electrical energy for a lot of motion. Polymers are better for large forces of motion, but don’t have a lot of strength. So, you can stretch adequately, but may not even be able to pick up an egg. Nature has given us some elements, and now we’re going beyond and designing materials from the ground up. We wanted to combine the best qualities of the two types of piezoelectrics, among other things.”

Sharma has been working to refine his theoretical ideas for two years. His research team includes Ramanan Krishnamoorti of the UH Cullen College of Engineering, Boris Yakobson of Rice University and Zoubeida Ounaies of Texas A&M University. Krishanmoorit and Ounaies will begin putting the research to the test with the help of a $1.22 million grant from the National Science Foundation.

“The real applications of this technology are going to come from the fact that you don’t have to depend on existing piezoelectrics,” Sharma said. “You can create materials, using certain nanoscale effects, that give higher energy conversion. These are basically piezoelectrics on steroids.”

Note for Piezoelectricity

Piezoelectricity is the ability of some materials (notably crystals and certain ceramics) to generate an electric potential in response to applied mechanical stress. This may take the form of a separation of electric charge across the crystal lattice. If the material is not short-circuited, the applied charge induces a voltage across the material. The word is derived from the Greek piezein, which means to squeeze or press.

The piezoelectric effect is reversible in that materials exhibiting the direct piezoelectric effect (the production of electricity when stress is applied) also exhibit the converse piezoelectric effect (the production of stress and/or strain when an electric field is applied). For example, lead zirconate titanate crystals will exhibit a maximum shape change of about 0.1% of the original dimension. The effect finds useful applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies.

About the University of Houston

The University of Houston, Texas’ premier metropolitan research and teaching institution, is home to more than 40 research centers and institutes and sponsors more than 300 partnerships with corporate, civic and governmental entities. UH, the most diverse research university in the country, stands at the forefront of education, research and service with more than 35,000 students.

About the Cullen College of Engineering

UH Cullen College of Engineering has produced five U.S. astronauts, 10 members of the National Academy of Engineering, and degree programs that have ranked in the top 10 nationally. With more than 2,600 students, the college offers accredited undergraduate and graduate degrees in biomedical, chemical, civil and environmental, electrical and computer, industrial, and mechanical engineering. It also offers specialized programs in aerospace, materials, petroleum engineering and telecommunications.

About Researcher

Dr. Pradeep Sharma
Assistant Professor of Mechanical Engineering
Dept. of Mechanical Engineering 
University of Houston 
Engineering Building One 
Houston, TX 77204-4006

Office Location: N233
Telephone: (713) 743-4256
Fax: (713) 743-4503
E-mail: psharma@uh.edu