Electrothermal Dry Adhesives with High Adhesion Under Low Temperatures Based on Tunable Stiffness

Bioinspired dry adhesives relying on van der Waals interactions have shown great potential in object manipulation and climbing robots. Although substantial progress has been made in dry adhesives for extreme environments (such as vacuum and microgravity), robust adhesion at low temperatures, i.e., typical scenes in space or polar environments, is rarely achieved. Here, an electrothermal dry adhesive (EDA) based on tunable stiffness for low-temperature environments is proposed, which can be reversibly transformed between the soft and rigid state in low-temperature environments due to the electrothermal effect. The former is beneficial for conformal contact, while the latter is convenient for interfacial stress homogenization in the grasping stage. According to the adhesion strategy comprising soft contact followed by rigid gripping, the EDA demonstrates the adhesion of 1063 kPa at −90 °C, i.e., 1022 times higher than conventional polydimethylsiloxane (PDMS) adhesives. Moreover, the EDA requires an energy supply (6 W at −90 °C) only during pressing, subsequently changing to the rigid state with no power consumption, which requires relatively low electrical energy compared to continuous heating methods. Such adhesion strategy extends the workable temperature of dry adhesives to −90 °C, opening up a new avenue for developing dry adhesives for harsh environments.