A. Geipel, F. Goldschmidtböing, A. Doll, C. Farhat, P. Jantscheff, N. Esser, U. Massing, and P. Woias (Germany)
Multilayer soft lithography, PDMS, polyurethane, microtechnology, packaging, life sciences
For biomedical applications the encapsulation of devices is a nontrivial task which has to meet ambitious specifications such as biocompatibility, mechanical and chemical stability, fluidic sealing or electrical isolation. Especially for microsystems the packaging is considered as a key process since it has to provide the interface between the microchips and the outer world. For life science applications polydimethylsiloxane (PDMS) has been widely employed, particularly for the formation of multilayer stacks. In our concept the multilayer approach is employed to design a multilayered housing for an active microport with embedded functional structures. In addition to PDMS, we explored polyurethane (PU) as a suitable material for the multilayer technique. Compared to PDMS it excels by an even better transparency and a slightly higher mechanical stability. Moreover, a large number of glues work with PU whereas adhesives for PDMS are rarely found. For our application the bond strength is an extremely critical parameter due to the demand of an absolutely reliable sealing. Several bonding techniques such as adhesion, annealing, mixing ratio variation and adhesive layers have been compared considering the reversibility of the bond type and the bond strength. An experimental setup has been developed which applies a load to the bond interface and determines the maximum applicable force.
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