Background: Piezoelectric materials produce electric charge in response to mechanical stress. Such materials can be utilized as very small ‘nanogenerators’ that absorb vibrations from the environment (e.g. acoustic waves car motion etc.) and output sub-milliwatt energy. This is sufficient to power LEDs speed sensors and other small devices. Although exciting nanogenerators require bendable components not easily integrated with portable electronics like cell phones. New nanogenerator designs must be simpler to fabricate and have good energy conversion efficiency. Technology Description: UW–Madison researchers have developed a thin piezoelectric film that converts ambient vibrations into electrical energy and can be directly integrated onto the surface of a device. The film is made by dispersing metal oxide or other nanoparticles into a solution of a piezoelectrically active polymer like PVDF (polyvinylidene fluoride). The solution is allowed to dry into a sponge-like layer. The nanoparticles then are etched away or otherwise removed. This leaves a finely porous matrix that can be sandwiched between electrodes to create a nanogenerator. Applications: Nanogenerators for wireless sensors battery chargers laptops tablets and other portable electronics
1) Design is simple and compact. 2) Enables piezoelectric material to be thin and flexible. 3) Film can be directly attached to devices eliminating the need for other components. 4) Films can be tailored for desired characteristics based on the size and distribution of nanoparticles.