Surfacemicromachined in-channel Parylene dual valves for unpowered microflow regulation

This paper presents the world’s first in-channel parylene dual-valved microfluidic system for unpowered microflow regulation. Incorporating a normally-closed and a normally-open passive check valve in a back-to-back configuration inside a microchannel, the dual-valved system has successfully regulated the pressure/flow rate of air or liquid without power consumption or electronic/magnetic/thermal transduction. By exclusively using parylene C as the structural material, the fabricated valves have higher flexibility to shunt flows in comparison with other conventional thin-film valves. In addition, the parylene-based devices are completely biocompatible/implantable, and provide an economical paradigm for fluidic control in integrated lab-on-a-chip systems. Testing results have successfully demonstrated that the microflow regulation of the dual-valved system can achieve mmHg pressure – mL/min flow rates for air and mmHg pressure – μL/min flow rates for water. This regulation range is suitable for controlling biological conditions in human healthcare, such as regulating elevated intraocular pressure (IOP) in glaucoma patients