An optical 3D force sensor for biomedical devices

In this paper we describe the development of an optical sensor that is low profile, inexpensive, physically robust, and suitable for contact with soft tissue. It is constructed using commercially available integrated circuits, a printed circuit board, and layers of silicone elastomer. The sensor exhibits modest drift and hysteresis, as well as some temperature sensitivity, for which we compensate. We demonstrate how the raw sensor signals can be used to infer both normal and shear forces. The sensor proves to be particularly sensitive to shear forces, reporting them accurately and with minimal coupling between them.