Synthetic muscle built from gold-plated onion skin

Scientists have used onion cells to develop a new and inexpensive class of artificial muscle that can bend and contract at the same time.

In a world first, physicists in Taiwan discovered that the onion's epidermis – the delicate layer of skin between the layers of an onion – could help them create a cheaper and more versatile muscle for use with humans and robots.

"The initial goal was to develop an engineered micro-structure in artificial muscles for increasing the actuation deformation [the amount the muscle can bend or stretch when triggered]," said lead researcher Wen-Pin Shih.

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"One day, we found that the onion's cell structure and its dimensions were similar to what we had been making," he said.

The onion cells were coated with gold electrodes to make them move like muscles. Scientists were able to make them expand or contract to bend in different directions depending on the voltage used.

To demonstrate its application, the scientists developed muscle-like "tweezers" made up of the coated cells, which they used to pick up a cotton ball.

But the tweezers were only strong enough to pick up 2mg at a time and required a high voltage, which developers say is the concept's main drawback. "We will have to understand the configuration and mechanical properties of the cell walls better to overcome this challenge," explained Wen-Pin Shih.

Artificial muscles have a wide range of real-word applications, from helping people with debilitating injuries to powering robots.

"If the new muscle becomes viable for production, it could be a valuable tool for the emerging world of soft robotics," says The Verge. Robots can currently only perform simple motor functions such as contracting, expanding and rotating, but experts hope that advancements in technology might one day combine all of those functions into a "single, all-purpose" muscle.