Autonomic perspiration in 3D-printed hydrogel actuators

Area of Science:

• Soft Robotics
• Biomimetic Engineering
• Materials Science

Background:

• Effective thermoregulation is crucial for sustained peak performance in biological and engineered systems.
• Existing engineered systems often lack efficient, autonomous cooling mechanisms comparable to biological counterparts.

Purpose of the Study:

• To develop a soft hydrogel-based actuator capable of autonomic perspiration for active thermoregulation.
• To investigate the potential of this sweating actuator in enhancing cooling rates and enabling thermal manipulation.

Main Methods:

• Utilized multimaterial stereolithography to 3D print finger-like fluidic elastomer actuators.
• Incorporated a poly-N-isopropylacrylamide (PNIPAm) body and a microporous polyacrylamide (PAAm) dorsal layer.
• Leveraged the temperature-dependent chemomechanical response of hydrogels for controlled pore dilation and perspiration.

Main Results:

• The sweating actuators demonstrated a 600% enhancement in cooling rate (39.1°C minute⁻¹) compared to non-sweating devices.
• Achieved thermoregulatory performance of approximately 107 watts kilogram⁻¹, significantly exceeding animal systems (~35 watts kilogram⁻¹).
• Developed soft robotic grippers using multiple actuators capable of mechanically and thermally manipulating heated objects.

Conclusions:

• The developed hydrogel-based sweating actuators offer a highly efficient, biomimetic approach to thermoregulation.
• These actuators provide a promising platform for applications requiring active cooling and thermal management in soft robotics.
• The system achieves superior cooling capacity at the expense of a temporary reduction in actuation efficiency.