A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak (～10nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000bacteriaml ~(- 1) at the level of relative standard deviation of 0.994 and detection limit of 20bacteriaml~(- 1). The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.
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