LCD 3D Printing of a Normally Closed Fluidic Transistor via Additive Assembly

Fluidically actuated soft robotic devices have attracted increasing interest due to their ability to provide benefits over traditional rigid systems in biomedical applications such as minimally invasive surgery, rehabilitative devices, and prosthetics. Unfortunately, challenges remain for controlling the fluidic operations of such systems, driving a critical need for new classes of fluidic circuit elements. Here we explore the use of “Liquid Crystal Display (LCD)” 3D printing-a low-cost vat photopolymerization (VPP) approach-to additively manufacture “normally closed” fluidic transistors with operations analogous to their electronic counterparts. Specifically, we leverage an “additive assembly” strategy wherein part components are printed separately and assembled post hoc. Experimental results for higher source pressure magnitudes revealed that in the absence of an applied gate pressure, the element obstructed source-to-drain fluid flow-i.e., normally closed behavior-however, by applying a gate pressure of 2::25 kPa, the element permitted source-to-drain fluid flow. Thus, this work establishes the efficacy for VPP-based additive assembly of fluidic circuit elements, which could help to advance and democratize fluidic circuit-based soft robotic technologies.