Out-of-Plane Soft Lithography for Soft Pneumatic Microactuators Arrays

Abstract

Elastic pneumatic actuators are fuelling new devices and applications in soft robotics. Actuator miniaturisation is critical to enable soft microsystems for applications in microfluidics and micromanipulation. This work proposes a fabrication technique to make out-of-plane bending microactuators entirely by soft lithography. The only bonding step required is to seal the embedded fluidic channels, assuring the structural integrity of the microactuators. The process consists of fabricating two SU8 mold halves using different lithographic layers. Polydimethilsiloxane (PDMS) is poured on the bottom mold, which is subsequently aligned and assembled with the top mould. The process allows for out-of-plane actuators with a diameter of 300 µm and for fabricating arrays of up to 36 actuators that are row-addressable. These active micropillars have an aspect ratio of 1:1.5 and when pressurized at 1 bar, show a bending angle of approximately 30°.