Now there is more use for onion than just in food, as scientists have created artificial muscles from the vegetable.
Unlike previous artificial muscles, this one, created by a group of researchers from National Taiwan University, can either expand or contract to bend in different directions depending on the driving voltage applied.
Lead researcher Wen-Pin Shih said that the initial goal was to develop an engineered microstructure in artificial muscles for increasing the actuation deformation the amount the muscle can bend or stretch when triggered, and they found that the onion's cell structure and its dimensions were similar to what they had been making.
The onion epidermis-the fragile skin found just beneath the onion's surface-is a thin, translucent layer of blocky cells arranged in a tightly-packed lattice. The researchers treated the cells with acid to remove the hemicellulose, a protein that makes the cell walls rigid. Then, they coated both sides of the onion layer with gold. When current flowed through the gold electrodes, the onion cells bent and stretched much like a muscle.
To demonstrate their device's utility, the researchers combined two onion muscles into a pair of tweezers, which they used to pick up a cotton ball. In the future, they hope to increase the lifting power of their artificial muscles.
Shih said their next step would be to reduce the driving voltage and the actuating force.
The finding is published in the journal Applied Physics Letters.