Cellulose. It’s one of the most common bio-materials on earth. It’s the substance that gives plants the ability to stand up, from blades of grass to might oaks. It’s the by-product of practically all plant food production in the world. And unless you’re a termite or a cow (or actually, the bacteria that live in those animals), you can’t digest it to access its energy. Efforts are underway to turn it into a sustainable biofuel, which could reduce dependency on fossil fuel sources. But this common material may also find a role in generating tiny amounts of power.
Researchers at Jadavpur University in Kolkata, India have harnessed the piezoelectric property of cellulose to convert motion into electricity. Cellulose is a natural polymer, and the researchers were able to create a flexible energy harvesting device without having to modify the original material. They combined it with polydimethylsiloxane, which is a form of silicone plastic that is used in breast implants. To transport the electricity that is generated, they added carbon nanotubes (CNT) to the mix. Repeated pressing generates enough power — about 9 micro Watts per cubic centimeter — to light up dozens of LEDs. They also demonstrated the ability to store the electricity in capacitors that could then be used to power a calculator and a wrist watch.
Using bio-compatible materials such as cellulose and silicone, the researchers hope that their device can be implanted in a person’s body. It could be used to harvest energy from repeated body motion, from heart beats and breathing to moving limbs. The electricity generated could generate sensors, transmitters, and other wearable devices without the need to recharge or replace batteries.