Robot hand can 'sweat' to cool itself down

James Marshall
February 1, 2020

The team, which includes a scientist from Facebook's reality lab, are hopeful it will eventually be a more reliable alternative to bulky cooling systems in use today. Researchers took inspiration for cooling a soft robot from how mammals stay cool - sweating.

"The ability to perspire is one of the most remarkable features of humans", Wallin stated in a press release from Cornell.

That's due to the fact that versatile, artificial products hold warm from the inner engines that run the robot- unlike steels, which dissipate warm promptly. “Sweating takes advantage of evaporated water loss to rapidly dissipate heat and can cool below the ambient environmental temperature.

The scientists, from Cornell University in NY, established the robot hand from hydraulically managed "fingerlike actuators" that have little openings which can produce water. "So as is often the case, biology provided an excellent guide for us as engineers". At temperatures below 30 C, the pores remain closed.

When the fingers reach a temperature of 30°C (86°F), the base layer reacts by shrinking, squeezing the water through the top micron-sized pores in the top layer.

The researchers mounted several of the sweaty fingers on a rigid "palm" to create a hand that could grip hot objects of different shapes and sizes, and found that simulated sweating was even more effective in cooling the robot than human perspiration.

The artificial skin that allows robots to feel
Robot hand can 'sweat' to cool itself down

In testing the sweating actuators cooled off about six times faster than their non-sweating counterparts when exposed to wind from a fan. '18 said, "The best part of this synthetic strategy is that the thermal regulatory performance is based in the material itself".

Shepherd said, "The team incorporated the actuator fingers into a robot hand that could grab and lift objects, and they realized that autonomous sweating not only cooled the hand but lowered the temperature of the object as well". We did not need to have sensors or other components to control the sweating rate.

However, it will be a while before they start appearing in mainstream technology, as the team haven't been able to find a way to replenish water lost during operation.

One disadvantage of the technology is that it can hinder a robots mobility. "This brings up a point [about the importance of] multidisciplinary research in this area, where really no one group has all the answers".

In the future, "sweat" could be used to allow robots to self-lubricate for a smoother movement (think of robot slugs) or excrete enzymes to "digest" the materials on which they move.

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