Low-cost, portable dual-channel pressure pump for droplet microfluidics

Due to the high cost and complexity of instrumentation in droplet microfluidics, droplet generation has been limited to a small subset of the scientific community. In addition, scientific value is not in droplet generation, but rather in monodisperse microreactor environments created in droplets. To reduce the complexity of droplet generation, we designed a low-cost (~250 €), portable, dual-channel microfluidic pressure pump. In contrast with commonly used syringe pumps, our pump could control both phases in a two-phase flow simultaneously and pump continuously without refilling. Furthermore, it had wireless remote control and was battery-powered for portability. The pump was controlled through a dual core ESP32 DevKitC board, which enabled concurrent management of wireless access and flow control. Pressure setpoints could be configured remotely via Wi-Fi using a web browser based graphical user interface. Low-pulsation, continuous flows were produced by piezoelectric diaphragm pumps and regulated by closed-loop control of the pressure drop through the microfluidic chip. The pump could produce flow rates between 10-2050 μl/min for different liquid viscosities. Powered from its internal 3.7 V, 4 Ah battery, the pump could operate for >10 h at maximum load.