Flow actuation and control is being largely studied, aiming at a wide range of applications including medical diagnostics, chemical and biological analysis, etc. Micronozzles, microvalves, micropumps, and microfluidic devices, have been considered with this purpose. Because of their relatively simple structures, with no movable part, microfluidic amplifiers can be considered an attractive alternative for applications that require that a main flow be directed to one of two (or multiple) outputs.
Microfluidic amplifiers are being analyzed with respect to the activation process. Both hydraulic and thermal activation of devices with different geometries are being considered.
These type of microfluidic devices, schematically presented in the figure, have at least four basic functional parts: (1) a supply port, (2) control ports, (3) output ports, and (4) an interaction region. The fluid flow emerging from the supply port generates a jet which interacts with flows from the control ports in the interaction region. As a result, the jet from the supply nozzle is directed to one or another output, depending on the pressure/flow of the control ports.
The microfluidic amplifiers are being implemented by means of bulk micromachining processes, including silicon plasma etching for microchannels fabrication and anodic bonding for sealing. In order to achieve thermal activation, free-standing filaments will be integrated in the control ports of the microfluidic amplifiers by using sacrificial layer technology.
Special attention is given to the filament fabrication process that has LPCVD polysilicon as the material of the structural layer and PECVD silicon oxide as the material of the sacrificial layer.
The resulting microfluidic amplifiers will be probed with a sample holder that will be part of a hydraulic circuit containing pressure and flow sensors.
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