sweating robot hand

‘Sweating’ robot developed to keep cool during intense activities

Image credit: cornell university

A soft robot muscle has been developed that can regulate its temperature through sweating in much the same way that humans do.

As robotic technology advances and machines begin to carry out more demanding tasks, the heat they generate is likely to increase, running the risk of malfunctioning if not cooled down.

The Cornell University research team believe that the technology should allow high-powered robots to operate untethered for long periods of time without overheating.

The kinds of high-torque density motors and exothermic engines typically used in robots make overheating a common hazard.

This is a particular issue for soft robots, which are made of synthetic materials. While more flexible, they hold their heat, unlike metals, which dissipate heat quickly. An internal cooling technology, such as a fan, may not be much help because it would take up space inside the robot and add weight.

The new system sees machines “sweating” off cooling liquid stored around actuators, the component responsible for moving and controlling a mechanism or system.

“To thermal regulate, engineered systems often have dedicated components - our laptops have fans, cars have radiators - unfortunately there’s a penalty to these strategies,” said Thomas J. Wallin, a research scientist at Facebook reality lab, who worked on the project.

“The cooling components take up valuable space inside our electronics and they add weight. Additionally, these components are conventionally made from rigid materials that are incompatible with fully soft robots.

“To realise the numerous advantages of soft robots, we wanted to explore a thermo regulatory strategy that was compatible with soft polymeric materials.”

The researchers fabricated finger-like actuators (pictured above) composed of two hydrogel materials that can retain water and respond to temperature - in effect, “smart” sponges.

The base layer, made of poly(N-isopropylacrylamide), reacts to temperatures above 30°C by shrinking, which squeezes water up into a top layer of polyacrylamide that is perforated with micron-sized pores.

These pores are sensitive to the same temperature range and automatically dilate to release the “sweat”, then close when the temperature drops below 30°C.

In testing, the sweating actuators cooled off about six times faster than their non-sweating counterparts when exposed to wind from a fan.

The researchers said there is still work to do before the system can be commercialised as sweating efficiency temporarily dampened the robot’s ability to move and they are yet to find a way to replenish the water lost during extended operation.

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