Artificial muscles to make your eyes water…

By using onion skin cells, scientists have developed an artificial muscle that can bend and contract at the same time.

A research team from National Taiwan University used gold-plated onion cells to create an elastic muscle that could simultaneously expand or contract while bending when an electric field was applied.

“The initial goal was to develop an engineered microstructure in artificial muscles for increasing the actuation deformation. One day, we found that the onion’s cell structure and its dimensions were similar to what we had been making,” said lead researcher Professor Wen-Pin Shih.

In the study, published in Applied Physics Letters, the team treated onion epidermis cells with acid to remove a protein – hemicellulose – that makes the cell walls rigid. Each side of the cells was then unevenly coated with gold.

[caption id="attachment_43245" align="alignright" width="240"] Credit: SHIH LAB, NATIONAL TAIWAN UNIVERSITY[/caption]

“We intentionally made the top and bottom electrodes a different thickness so that the cell stiffness becomes asymmetric from top to bottom,” said Professor Shih.

The results showed that that when current flowed through the golden electrodes, the onion cells bent and stretched like a muscle. By modulating the voltage magnitude, the scientists observed deflection of the artificial muscle in different directions while either contracting or elongating. At low voltages, from 0–50V, the cells expanded and bended down, but they contracted and bended upwards between 50–1000V.

“We found that the single-layer lattice structure can generate unique actuation modes that engineered artificial muscle has never achieved before,” said Professor Shih.

By combining two onion muscles into a pair of tweezers, the team managed to pick up a cotton ball, showing the device’s utility.

The team now hopes to increase the lifting power of the artificial muscles.

Paper: http://scitation.aip.org/content/aip/journal/apl/106/18/10.1063/1.4917498