A nL/min-Scale Valveless Flow Regulator for Integrated Micro Chemical Devices(<Special Issue>Micro Mechanical Engineering)

A micro flow regulator with a capability of continuous volume flow control of a ultra-small volume flow rate liquid in nL/min scale is reported. A valveless principle based on the temperature dependence of liquid viscosity and the parylene-based freestanding micro channel structure enabled an extremely simple structure of the regulator element. This simplicity and the small footprint are advantageous over other mechanically movable regulation valves as the driving element for integrated chemical devices that require flexible control of liquid flow. A prototype device was fabricated with the surface micromachining technology. The experimantal results using de-ionized (DI) water as working fluid showed that the flow rate was continuously controlled in the range of 100-200% of that in the room temperature regardless of the applied pressure drop, successfully proofing the initial concept.