Progress is a fight between what works the best and what's feasible to manufacture cheaply at scale. Usually the latter wins. It's why we used VHS instead of Betamax. It's why most grocery store produce is utterly tasteless. And it's why we've built a humanoid robot that sweats. Image: spectrum.ieee
One of the major challenges facing robotics is heat, which starts to effect performance if it isn't properly dissipated. There are a variety of active cooling systems that can solve that problem by pumping cooled liquid through artificial veins and arteries, but those tend to be expensive (not to mention heavy). For a cheaper but no less elegant solution, researchers the University of Tokyo's JSK Lab borrowed sweating as a cooling concept from the playbook of nature for their Kengoro robot.
The perspiration (that is, deionised water) drips onto Kengoro's 108 motors, cooling them down through evaporation. While not quite as effective as those active cooling systems, sweating allows the bot to do push-ups for 11 minutes without overheating. It can run for half a day on just one cup of water.
Kengoro, of course, doesn't have any skin. Instead it sweats from its bones, which is incredibly smart and deeply unsettling to imagine. That soggy skeleton is made by laser sintering, a process similar to 3D printing that allows metal of various densities to be built up into complex shapes. Channels of less dense aluminium run through Kengoro's frame which act like a sponge, retaining water and making sure the "sweat" drops onto the motors instead of all over the floor.
Sweaty robots are the future, people. Lets hope that's the only biological process that turns out to make bots more efficient.