Scientists Make Artificial Muscles Out of Onion Skin


Image Credit: Osvaldo Gago via Wikimedia Commons // CC BY-SA 3.0

The key to making artificial muscles may be sitting on your kitchen counter. Scientists at National Taiwan University have discovered that onion skin cells can mimic the movement capabilities of muscle tissue.

Rectangular onion epidermis cells are arranged in a single-layer lattice pattern. The researchers peeled onions and freeze-dried a selection of skin cells, treating them with acid and coating them in gold electrodes on either side, as they describe in a study published in Applied Physics Letters. The gold coating was applied in a different thickness on each side of the onion skin so that the cells would bend when an electric charge was introduced. 

Image Credit: Chen et al., Applied Physics Letters

The onion "muscles" expand or contract, bending in different directions based on the voltage applied. A low voltage caused the cells to flatten and bend downward, while a higher voltage caused the cells to contract and bend up.

Image Credit: Chen et al., Applied Physics Letters

To test the potential of the artificial muscle, the researchers shaped the gold-coated onion cells into a pair of tweezers, then successfully used them to pick up a cotton ball. It’s not exactly Hulk-level stuff, but still, that’s pretty strong for a root vegetable. 

Scientists are keen to mimic the abilities of actual muscles for use in robotics and powered exoskeletons that enhance mobility both for therapeutic and military applications, and this isn’t the first attempt to create artificial muscles. One recent project made them out of fishing line and thread. However, previous artificial muscles haven’t been able to both stretch and contract simultaneously as the onion muscles can, and the fact that onion cells don’t need to be manufactured makes them an attractive material. 

[h/t: Newswise]