Biocompatible packaging of vectorial micro force sensors applied in laparoscopic surgery robots

Radó, János and Dücső, Csaba and Battistig, Gábor and Szebényi, Gábor and Nawrat, Zbigniew and Rohr, Kamil and Fürjes, Péter (2016) Biocompatible packaging of vectorial micro force sensors applied in laparoscopic surgery robots. In: Proceedings of the Symposium on Design, Test, Integration and Packaging of MEMS/MOEMS (DTIP'16). IEEE, New York, pp. 1-4. ISBN 9781509015054

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Abstract

3D force sensors were developed to further integration in laparoscopic heads of surgery robots. The Si sensors operate with piezoresistive transduction principle by measuring the stress induced signals of the symmetrically arranged four piezoresistors in the deforming membrane. As the chip size has to be reduced to a few mm2 , the conventional anisotropic alkaline etching technique was replaced by deep reactive ion etching (DRIE) for membrane formation. Besides, DRIE has no practical limitation in membrane geometry and offers the formation of monolith force transfer rod protruding over the chip surface. SOI (silicon on insulator) wafers of appropriate device layer thickness provide the uniformity of membranes and reproducibility of the process. According to the medical and functional requirements the MEMS sensors will be covered by biocompatible elastic polymer coating. Nevertheless, the elastomer drastically effect on the performance of the device. Therefore, the proposed sensor structures were modelled by coupled finite element simulation to determine the appropriate geometric parameters to meet the functional requirements. Sensors were covered with spherically shaped PDMS (polydimethylsiloxane) polymer and the effect of the elastic coating was also studied in terms of sensitivity and response time. Finally the design of the laparoscopic head integrating the 3D MEMS force sensors is also demonstrated.

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