An ultrasonic welding based process for building up a new class of inert fluidic microsensors and -actuators from polymers

In this paper, a process for building up a new class of polymer fluidic microsensors and -actuators with foreign matter free, physicochemically inert flow paths for applications in the field of pharmaceutics, biotechnology and life sciences as well as for high temperature automotive applications is presented. It is based on first time ultrasonic (US) welding of real micro polymer parts. The performance of this novel ‘micro US welding’ based process, alone using standard US welding equipment, is demonstrated by the example of covering and sealing microchannels and assembling micro membrane check valves and a piezo driven micro membrane pump. With the welding power as process termination criterion, accuracies of the relative welding depth in the range of only ±1 μm were achieved. The sealed channels have a width and depth of 500 μm. The outer size of the cuboidal single check valves is 3 mm × 3 mm × 2 mm. The valves show a low flow resistance in forward direction and shut tight in reverse direction. The discoidal piezo pump has a diameter of 14 mm. Delivering water, the pump achieves a maximum flow rate and back pressure of about 3 ml/min and more than 750 hPa, respectively.