Open-Source Pressure Controller Based on Compact Electro-Pneumatic Regulators for Droplet Microfluidics Applications

Abstract

Microfluidics is a rapidly growing area that provides innovations in biotechnology, medical diagnostics, and life science. Along with the commercial solutions, there are open-source projects aimed to make such technologies more affordable and flexible for end users. In this article, we developed an open-source, low-cost, and easy-to-use microfluidic pressure controller with a modular design based on electropneumatic regulators to introduce liquids into microfluidic devices under constant pressures. For implementation of complex experimental protocols, the controller contains a vacuum pump, relay outputs, analog inputs, and digital inputs/outputs to connect external equipment. It can be operated using five displays and an encoder or from a personal computer in a manual or automatic regime through the custom open-source software. In this study, we applied this pressure controller for the generation of water-in-oil droplets in microfluidic flow-focusing droplet generators. Droplets&#x2019; diameters linearly depended on the dispersed and continuous phases&#x2019; ratio in the range 5&#x2013;<inline-formula> <tex-math notation="LaTeX">$65 \mu \text{m}$ </tex-math></inline-formula>. In all the cases, the generation regimes were stable for at least 4 h. Direct comparison of the droplet generation obtained with the developed pressure controller and precise syringe pumps showed that it will suit the needs of the microfluidic community for different flow-based lab-on-a-chip applications, as a more affordable and flexible solution for introducing liquids and controlling flow sensors, heaters, valves, light sources, and so on during experiments.