Self-assembly of Micro Pumps with High Uniformity in Performance

In this paper we report a novel capillary-force-driven selfassembly technique which proceeds in an air environment. We demonstrate this technique for the self-assembly of piezoelectric driving elements (PZT) for diffuser valve micropumps: with the agitation of an orbital shaker, square PZT actuators self-align and mount to the hydrophilic trench binding sites with electric connections by heat curable lubricant oil and conductive physical contact between the PZT actuators and the substrate. 28 pumps are fabricated on a 4-inch bonded pyrex/silicon substrate. The resonance frequencies of all the pumps show high performance uniformity: the average is 80.1 kHz and standard deviation is 2.0 kHz. This technique provides fast, parallel and well-controlled bonding of bulk PZTs for micro pumps with yield ratio up to 100%.