Fabrication of porous silicon-based optical sensors using metal-assisted chemical etchingElectronic supplementary information (ESI) available: Materials and methods, experimental details, additional SEM images. See DOI: 10.1039/c5ra26816h

Optical biosensors based on porous silicon were fabricated by metal assisted chemical etching. Thereby double layered porous silicon structures were obtained consisting of porous pillars with large pores on top of a porous silicon layer with smaller pores. These structures showed a similar sensing performance in comparison to electrochemically produced porous silicon interferometric sensors. Metal-assisted chemical etching was exploited for fabricating a porous silicon double beam interferometer composed of pillars with large pores on top of a monolayer with smaller pores which can act as a sensing and reference channel, respectively.