Pneumatic impulsion device for microfluidic systems

Abstract

Design, fabrication and characterization of a highly integrable fluid impulsion microdevice developed for microfluidic systems are presented in this paper. The device is composed by a chamber and a single-use microvalve that connects its output port to an external microfluidic circuit. Due to the in-plane structure, a high integration with microfluidic and electronic components can be achieved. The activation is based in the combination of mechanical to thermal phenomena. The thermal effect is producing by making an electrical current flow through a resistor, and the mechanical one by applying a differential pressure. The combination of these phenomena at the time of activation produces a reduction of the required electrical energy with respect to other devices, and also enables fluid movement. It is based on the simultaneous application of a temperature ramp that weakens the membrane and a pressure difference that provokes its collapse, bringing on also the impulsion of the fluid. The in-plane structure allows the embedding of a thermal actuator, maximizing the heat transfer to the membrane. Another significant advantage of this structure is manufacturing a series of microdevices in an array, which has been reported. As a result of the integration of SU-8 and PCB-MEMS technologies in the fabrication of the device, fully integrated microfluidic circuits can be implemented within a PCB substrate without the need of complex interfaces to external impulsion actuation. The integration also incorporates outstanding advantages as the possibility of integration with sensing and auxiliary electronics and the drastic decrement of the fabrication cost. A series of microvalves has been characterized varying their parameters of fabrication, leading to a device that requires 0.35 J of electrical energy and supports a range of differential pressures from 50 to 400 kPa.