Elastomer microspring arrays for biomedical sensors fabricated using micromachined silicon molds

摘要

An approach to the implementation of micromachined structures in silicon suitable for use in the molding of large area elastomer microspring arrays is presented. Such arrays are of interest as primary sensing elements in the development of improved biomedical interface pressure sensors having low profile but with relatively large area so as to reduce interface measurement artifacts. The approach exploits the special features of anisotropically etched silicon to generate molds which are then used to form elastomer microspring array structures with individual array element shapes designed to optimize spring mechanical performance parameters. The basic shape used is a trench of trapezoidal cross section with depth in the range 5-40 mum, and length which may extend close to the edges of the die, i.e. 9.5 mm long. The molding process produces complementary elastomer structures with corresponding precision to that of the molds. Preliminary, stress-strain results for the arrays are inconsistent with simple elastic theory. However, it is found that a straightforward interpretation of the data is possible using the elastic theory for large deflections by incorporating an empirical shape factor adjustment. Experimentally determined Young's moduli ranged from 300 kPa to 560 kPa for the microspring arrays tested. This approach offers the potential to match and optimize elastomer microspring array mechanical properties to specific biomedical interface sensor requirements. [References: 21]