Polymer film capable of generating electricity by harnessing the power of water vapour

14-Jan-13

A polymer film that generates energy using water vapor has been created by MIT engineers at the David H. Koch Institute for Integrative Cancer Research. The film makes use of two different polymers: a hard but flexible layer matrix and a soft gel that expands when it comes in contact with moisture. Together, the film contracts it comes in contact with water, causing the material to curl up. When the wet surface is exposed to air, the moisture is released and the cycle repeats. The polymer could be used as an actuator to control robotic limbs, or act as a generator when paired with a piezoelectric material that converts mechanical stress into electricity. The energy created by the film can be used to power small sensors or nanoelectronics without the need for batteries. The 20-micrometre-thick polymer film is able to take advantage of very small amounts of moisture. In the video above you can see pieces of the film absorbing evaporated water from a damp surface and beginning to curl up. Once the bottom layer is exposed to the air it releases the moisture and uncurls before beginning the process again. As a result the chemical energy of the water gradient can be transformed into mechanical energy.