%AMishra, Anand%AWallin, Thomas%APan, Wenyang%AXu, Patricia%AWang, Kaiyang%AGiannelis, Emmanuel%AMazzolai, Barbara%AShepherd, Robert%BJournal Name: Science Robotics; Journal Volume: 5; Journal Issue: 38 %D2020%I %JJournal Name: Science Robotics; Journal Volume: 5; Journal Issue: 38 %K %MOSTI ID: 10148494 %PMedium: X %TAutonomic perspiration in 3D-printed hydrogel actuators %XIn both biological and engineered systems, functioning at peak power output for prolonged periods of time requires thermoregulation. Here, we report a soft hydrogel-based actuator that can maintain stable body temperatures via autonomic perspiration. Using multimaterial stereolithography, we three-dimensionally print finger-like fluidic elastomer actuators having a poly- N -isopropylacrylamide (PNIPAm) body capped with a microporous (~200 micrometers) polyacrylamide (PAAm) dorsal layer. The chemomechanical response of these hydrogel materials is such that, at low temperatures (<30°C), the pores are sufficiently closed to allow for pressurization and actuation, whereas at elevated temperatures (>30°C), the pores dilate to enable localized perspiration in the hydraulic actuator. Such sweating actuators exhibit a 600% enhancement in cooling rate (i.e., 39.1°C minute −1 ) over similar non-sweating devices. Combining multiple finger actuators into a single device yields soft robotic grippers capable of both mechanically and thermally manipulating various heated objects. The measured thermoregulatory performance of these sweating actuators (~107 watts kilogram −1 ) greatly exceeds the evaporative cooling capacity found in the best animal systems (~35 watts kilogram −1 ) at the cost of a temporary decrease in actuation efficiency. %0Journal Article