A Microfabricated Pistonless Syringe Pump Driven by Electro‐Conjugate Fluid with Leakless On/Off Microvalves

Abstract In contrast to microfluidic devices, bulky syringe pumps are widely used to deliver a small amount of solution with high accuracy. Miniaturizing the syringe pump is difficult due to the scale effect in the microscale where the friction of the piston–cylinder is dominant and there are few high‐power microactuators. To solve these problems, an on‐chip microsyringe pump without mechanical sliding parts and with high power sources is proposed. The microsyringe pump utilizes the interface between water and oil (electro‐conjugate fluid, ECF) instead of a piston and an electrohydrodynamic (EHD) flow driven by ECF in place of a linear actuator. ECF as a functional fluid has two capabilities: a) making the water–oil interface in microchannels and b) generating an active ECF flow at an applied voltage to withdraw and infuse aqueous solution by the interface. To control the flow direction, ECF‐driven leakless on/off microvalves are also integrated. It is demonstrated that the proposed ECF microsyringe pump synchronized with the ECF on/off microvalves can control the withdrawing and infusing of aqueous solution with high resolution and precision. The experiments prove the feasibility of the microsyringe pump to be embedded as a module for the precise and linear control of flow rates in microfluidic devices.