Although soft robotic graspers may be squishy on the outside, they usually still have hard, unyielding electronic components on the inside. A new and potentially more versatile bio-inspired grasping system, however, is 100 percent soft.
Developed by a team of scientists from China's Southeast University, the experimental grasper was inspired by plants such as the Venus flytrap, which move in response to environmental stimuli.
The researchers started with a slab of a polymer known as a liquid crystal elastomer (LCE), which changes its shape in response to changes in temperature. They then applied a liquid metal (nickel-infused gallium-indium alloy) to its surface, which they magnetically arranged into lines, forming an uninterrupted circuit. Finally, they sealed that circuit with a layer of silicone.
When an electrical current is run through that circuit, a small amount of heat is produced within the material. Subsequently applying mechanical pressure to the grasping surface stretches the circuit, causing the current and thus the material's temperature to drop. As a result, the LCE curls inward. Easing off on the pressure allows it to to return to its default flat state.
In this fashion, the scientists were able to grip small objects by pressing the grasper against them, causing it to curl. Those items could then be lifted, moved, and then dropped as the grasper uncurled after the initial pressure was released.
The device is demonstrated in the video below – in order to better visualize its morphing action, a type of silicone was used that changes from pink to red as its temperature rises.
A paper on the research was recently published in the journal ACS Applied Materials & Interfaces.
Source: American Chemical Society
