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A 3D rendering of molybdenum disulphide, used by Rutgers scientists to create a powerful new actuator — devices that work like muscles. (Credit: Shutterstock/ogwen)

Imagine repeatedly lifting 165 times your weight without breaking a sweat — a feat normally reserved for heroes like Spider-Man. Engineers have discovered a simple, economical way to make a nano-sized device that can match the friendly neighborhood Avenger, on a much smaller scale. Their creation weighs 1.6 mg and can lift 265 mg.

Its strength comes from a process of inserting and removing ions between very thin sheets of molybdenum disulfide (MoS2), an inorganic crystalline mineral compound. It’s a new type of actuator — devices that work like muscles and convert electrical energy to mechanical energy. The Rutgers discovery — called an inverted-series-connected (ISC) biomorph actuation device — is described in a study published online in the journal Nature.

Actuators are used in a wide variety of electromechanical systems and in robotics. They have applications such as steerable catheters, the study notes. The extremely thin sheets, also called nanosheets, remain suspended in solvents such as water.

The nanosheets can be assembled into stacks by putting the solution onto a flexible material and allowing the solvent to evaporate. The restacked sheets can then be used as electrodes with high electrical conductivity to insert and remove ions. Inserting and removing ions leads to the expansion and contraction of nanosheets, resulting in force on the surface. This force triggers the movement — or actuation — of the flexible material.

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