Composite porous silicon-crystalline silicon cantilevers for enhanced biosensing

Cantilever transducers, which are recognized as a promising platform for the next generation of chemical and biological sensors, are currently under extensive research. Here we report composite porous silicon-crystalline silicon microcantilevers made of SOI wafers, where the porous silicon surface provides an excellent interface for immobilization of the biosensing layer. We start with crystalline silicon cantilevers fabricated from SOI wafers and we establish a surface layer of porous silicon on the cantilevers by vapor phase stain etching. The processed porous silicon does not introduce significant static bending of the cantilevers indicating that it does not introduce significant residual stress. It does provide an excellent biocompatible material for immobilization of a wide variety of chemical and biological materials, resulting in enhanced sensitivity as demonstrated on the covalently immobilized antibody binding its complementary antigen.