A robot hand made from wood could be used in extremely hot environments while still maintaining a delicate touch.
Most robotic hand grippers are made from soft plastics, which can pick up objects without damaging them but melt at high temperatures, or from metals with many moving parts, which are stiff and complex to operate.
Now, at the National University of Singapore and his colleagues have developed wooden grippers made from 0.5 millimetre-thick pieces of Canadian maple, which clasp tighter as they warm up and then relax when exposed to high humidity.
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To make the device, Tan and his team applied sodium chlorite to remove the lignin from the wood, a glue-like component found inside plant cell walls, and replaced it with a polymer called polypyrrole so that the material can absorb heat more quickly. They attached a hydrophobic film to one side of the wood and a moisture-absorbing gel to the other.
鈥淎fter the wood has been modified, it can withstand high temperatures, like 200掳C. This is much better than a lot of polymer robotic hands that I鈥檝e seen so far,鈥� says Tan.
The team tested the wooden grippers in a range of different heat and humidity environments, and showed that a single 鈥渇inger鈥� weighing just 0.1 grams can support a 300g weight. They then created a robotic hand with five wooden fingers and used it to pick up a ball in 70掳C heat.
While it can work as a robotic hand, Tan says that the treated wood鈥檚 predictable bending in response to heat and moisture could make it useful as an eco-friendly thermostat or home sensor for humidity.
The team is now working on modifying the wood to make it work at temperatures above 200掳C, as the current version warps when heated too much.
Advanced Materials
