It is easy to lose sight of temperature regulation in the heat of battle. For humans, that comes with a risk of dehydration and exhaustion, as they sweat to avoid harm from heat. For machines, it means tolerating a wide range of temperatures or breaking. But what if a machine could sweat?
That is the somewhat unsettling question asked by a team of researchers at Cornell University. In mammals that sweat, it is an efficient method of rapid cooling. For a robot, the ability to shed moisture, and with it heat, can improve the ability to handle hot objects without suffering damage.
“Such sweating actuators exhibit a 600 percent enhancement in cooling rate over similar non-sweating devices,” write the authors of Autonomic perspiration in 3D-printed hydrogel actuators. “Combining multiple finger actuators into a single device yields soft robotic grippers capable of both mechanically and thermally manipulating various heated objects.”
With five soft robotic fingers attached to a rigid robotic hand, the researchers were able to test grip strength and resilience, as the special polymer passively sweat hydraulic fluid at a certain temperature threshold.
For work that requires brief exposure to intense heat, and then an ability to cool off quickly, such sweating robots could lend a hand. This might involve loading artillery, or carefully yet quickly disposing of spent shells, or repair work at moments where the danger is too great for humans but the task still requires a human-like finesse. It is easy to imagine the kinds of scenarios for such a machine on a military ship, especially, which is perhaps why the research was funded in part by the Office of Naval Research Young Investigator Program.
As a cooling mechanism, sweating in robots may be more efficient than it is even in humans, but it comes with a specific resource need. Sweaty robots are thirsty robots.
“Similar to animals that ingest food and water from their environment to sustain thermoregulated activity, our demonstrated system eventually requires a means to replenish lost water during extended operation,” write the authors.
That thirst and need for replenish is an opportunity in and of itself. The authors note that animals use fluid excretion for a range of purposes, and suggest future sweating robots could deliberately release coatings that make them more or less slippery, as the situation demands.
“The ability to selectively elute liquids from the robot body also provides for many other opportunities including ‘digesting’ and absorbing nutrients, catalyzing reactions, removing contaminants from the surface, or coating the surface of the robot with a protective layer,” write the authors.
For now, the principles explored suggest there’s real benefit in developing soft robots that can better handle heat. Retaining flexibility and durability in robotic limbs despite increases in temperature could be a valuable asset.
One that’s worth it even if it means the robots, as well as humans, need to rehydrate after a particularly heated firefight.
Watch the soft robot fingers sweat in action below: