Batch fabrication of polymer microsystems with shape memory microactuators
This paper introduces the technologies of ultrasonic welding and heat-activated bonding for batch integration of micromachined polymer layers and shape memory alloy (SMA) foils or films. A series of ultrasonic welding tests is performed to achieve matter-free bonds on the wafer level with vertical accuracy of 1 mum. Heat-activated bonding is tested for various pressure and temperature conditions using micromachined foils of 60 mum thickness. The technologies are combined in a new process flow for batch fabrication of mechanically active polymer microsystems. The process flow is validated by the fabrication and characterization of SMA-actuated polymer microvalves.
A Bistable Shape Memory Alloy Microvalve With Magnetostatic Latches
This paper presents the layout, fabrication, and characterization of a first-of-its-kind bistable shape memory microvalve. The main functional components are two counteracting shape memory alloy microbridges for switching and magnetic layers to maintain two stable switching states in power-off condition. The high demands on alignment accuracy are met by a novel fabrication process, where all components are assembled to a self-aligning valve stack. This allows full electrical, mechanical, and fluidic performance tests as well as fine adjustment of layer thicknesses prior to final bonding. The overall dimensions of first demonstrators are 11 mm × 6 mm × 3 mm. Bistable operation is shown for differential pressures up to 300 kPa for gas (N2) at high flow rates of 2200 seem.
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