UC Irvine

In this work, pneumatic digital logic systems (i.e., gates, ring oscillators, and peristaltic pumps) were demonstrated using high-resolution (20 µm) stereolithographic (SLA) 3D printing. Pneumatic digital logic systems are Boolean circuits that use pressure (instead of electricity). To this end, normally closed pneumatic membrane valves are configured analogous to NMOS transistors. Vacuum pressure represents logic "1" or True, while atmospheric pressure represents logic "0" or False. Using three alternative fabrication methods (CNC milling, photolithography, and laser-cutting), pneumatic digital circuits have been built to provide embedded control for physical systems (e.g., microfluidics and robotics). However, scaling and high-aspect-ratio manufacturing of these integrated circuits have remained difficult despite progress. Additive manufacturing (i.e., SLA 3D printing) is attractive for the high-aspect-ratio and scalable manufacturing of pneumatic digital systems. Utilizing the versatile design of SLA 3D printing, the circuit density of 3D-printed pneumatic ring oscillators was increased to approximately 7 gates per cm2, constraining complex pneumatic digital systems and eliminating off-chip controllers. Utilizing a 3-ring pneumatic oscillator to integrate a peristaltic pump, a liquid pump rate as high as 12 µL/sec was successfully demonstrated. In addition, a set-up that could support prolonged automated fluid experiments was implemented. Advances in SLA prototyping of pneumatic digital logic are strongly encouraged to facilitate futuristic microfluidic applications.