UC Riverside

Vacuum-based pneumatic logic is a computationally powerful method of controlling pneumatic devices, but it has minimal applicability due to inherently low flow rates and differential pressures. These circuits are typically composed of monolithic membrane valves that can be arranged to form Boolean logic gates (AND, OR, NOT, XOR, etc.) and circuits like demultiplexers and finite state machines. Pneumatic microfluidics are light, mass-manufacturable, and easily adaptable, however, their incapability to manipulate large volumes of air limits them to controlling lab-on-chip devices and relatively small systems. In this work, we present a modular 3D printable device called the “pneumatic level shifter” that can shift and amplify vacuum-based logic signals into positive pressure signals suitable for macro-scale pneumatic actuation. The level shifter contains “normally open” and “normally closed” pinch valves which externally regulate a fluidic flow input (e.g. positive pressure) by compressing tubing as vacuum signals are received by the control input. We designed a pressure-based oscillatory circuit by attaching level shifters to the outputs of 3, 5, 7, and 9 Boolean NOT microfluidic oscillators. This system produced stronger, amplified periodic pressure signals with about twice the pressure differential of the original vacuum signals from the microfluidics. As a proof-of-concept, we implemented a macro-scale oscillator powered by a 9 NOT microfluidic circuit and 8 level shifters into a soft pneumatic hexapedal tripod gait robot and observed autonomous forward movement. The pneumatic level shifter eliminates the need to reinvent logic gates, providing an easy solution for expanding existing vacuum-based logic to control large-scale devices.