The same piezoelectric effect that ignites your gas grill with the push of a button could one day power sensors in your body via the respiration in your nose. In a recent paper US scientists from the University of Wisconsin-Madison described a device that converts air flow from human breath into electricity. The device could power implantable biomedical devices as an alternative to batteries which often need replacing via surgery. The device relies on a technique that uses piezoelectric polyvinylidene fluoride (PVDF) microbelts to convert the energy from low speed air flow into electricity via resonant oscillation. During an experiment the PVDF microbelts were able to generate sufficient electrical energy from low speed air flor for the sustained operation of small electronic devices. Their capability for harvesting energy from simulated respiration was also deomonstrated.

Electricity from Nose - Human Respiration Generates PowerIn certain materials such as the polyvinylidene fluoride (PVDF), an electric charge accumulates in response to applied mechanical stress. This is known as the piezoelectric effect. The researchers engineered PVDF to generate sufficient electrical energy from respiration to operate small electronic devices.

“Basically, we are harvesting mechanical energy from biological systems. The airflow of normal human respiration is typically below about two meters per second,” says Xudong Wang, postdoctoral Researcher from the University of Wisconsin-Madison. “We calculated that if we could make this material thin enough, small vibrations could produce a microwatt of electrical energy that could be useful for sensors or other devices implanted in the face.”

Researchers are taking advantage of advances in nanotechnology and miniaturized electronics to develop a host of biomedical devices that could monitor blood glucose for diabetics or keep a pacemaker battery charged so that it would not need replacing. What’s needed to run these tiny devices is a miniscule power supply. Waste energy in the form or blood flow, motion, heat, or in this case respiration, offers a consistent source of power.

Wang’s team used an ion-etching process to carefully thin material while preserving its piezoelectric properties. With improvements, he believes the thickness can be controlled down to the submicron level. Because PVDF is biocompatible, he says the development represents a significant advance toward creating a practical micro-scale device for harvesting energy from respiration.