It has been reported that a group of researchers from National Taiwan University has created an artificial muscle from onion cells that can either expand or contract to bend in different directions.

The initial goal of the research was to develop an engineered microstructure in artificial muscles for increasing the actuation deformation (the amount the muscle can bend or stretch when triggered).

Lead researcher for the current study, Wen-Pin Shih said, "One day, we found that the onion's cell structure and its dimensions were similar to what we had been making".

The onion epidermis is the fragile skin found just beneath the onion's surface. It is a thin translucent layer of blocky cells arranged in a tightly-packed lattice.

Shih and his colleagues thought that onion epidermal cells might be a viable option for the tricky task of creating a more versatile muscle that could expand or contract while bending.

The researchers treated the cells with acid in order to remove the hemicellulose, a protein that makes the cell walls rigid.

Furthermore, they coated both the sides of the non layers with gold. And when the current flowed through the gold electrodes, the onion cells bent and stretched like a muscle.

Further in explanation Shih said they intentionally made the top and bottom electrodes a different thickness so that the cell stiffness becomes asymmetric from top to bottom.

He said the asymmetry gave them control over the muscle's response, low voltage made them expand and flex downwards, towards the thicker bottom layer.

On the other hand, a high voltage caused the cells to contract and flex upwards, towards the thinner top layer.

Furthermore, in order to demonstrate the utility of their device researchers combined two onion muscles into a pair of tweezers which they used to pick up a cotton ball.