Artificial Muscles by Microfluidic Microcapacitors

Abstract

Many modern applications require the generation of force by a means that is miniaturized, low-weight, compact, and electrically controlled. For example, this is necessary in human prosthetics, where size and degrees of freedom are some of the primary challenges. Furthermore, a variety of unmanned surface and underwater vehicles require electrically-operated acoustically-quiet propulsion that moves away from cavitation-inducing traditional propellers and hopefully also offers acoustic translucence. In particular, the reciprocal motion of pelagic fish fins is highly efficient energetically, and requires only a low-frequency low-strain deformation, so artificial muscles made of soft materials would be the correct solution. Finally, a range of robotics applications have the same demand for lightweight, compact, high-force actuators that can be controlled with precision and do not require an excessive number of joints and axes. One way to address this demand is by the production of artificial muscles.

We propose a miniaturized system of force actuation. It consists of a long stack of soft microfluidic capacitors, where the dielectric is made of the bulk material of the device while flexible electrodes are produced by filling microfluidic channels with soft conductors, e.g. electrolyte solution or conducting gel. Applying voltage to the two networks of electrodes produces electrostatic attraction force between the plates of each capacitor in the stack. The resulting contraction is transferred to the surrounding bulk material, which produces a macroscopic contraction of the material akin to human muscle fibers. The result is an artificial muscle fiber that is electrically actuated, compatible with large-scale integration and mass production by a variety of methods, most importantly 3D printing, which lends itself to inexpensive upscaling and automated manufacture.