John Roach/ NBC News
When scientist Mingming Ma interlocked two different polymers in hopes of creating a new type of electrode to stimulate atrophied muscles, he made something more powerful: an artificial muscle, or actuator, that can generate electricity by drawing on water vapor.
“The first time I synthesized this material, I put the film on my hand and I found it was just moving by itself,” the chemical engineer at MIT’s David H. Koch Institute for Integrative Cancer Research told NBC News. “That was very surprising, so I decided to find out why.”
Ma and colleagues discovered the material changes its shape after absorbing tiny amounts of water vapor. It curls up and down as it absorbs and expels the moisture. Harnessing this movement could, for example, drive robotic limbs or generate enough electricity to power small sensors.
To generate electricity, the artificial muscles are attached a piezoelectric material that converts mechanical energy into electricity.
“You just need a little bit of water gradient to make it work,” Ma said. “If you immerse this material completely in water, it doesn’t work.”
The material is made of a hard but flexible polymer called polypyrrole and another polymer called polyol-borate, which is a soft gel that swells when it absorbs water. The material expands when it absorbs water and contracts when it expels water…