A microcantilever sensor with integrated optical readout for antimicrobial drug discovery

We present the first microcantilever sensor with integrated optical readout capable of detecting liquid samples. The measurement of beam displacement is performed through on-chip waveguides using an external laser and a photodetector. This approach yields ap 0.4% change in power per nanometer displacement. The device is embedded in microfluidics and is used for detecting the amino acid homocysteine common in bacterial signaling pathways. It is aimed at providing a testing platform for new drugs that target bacterial communications. The minimal measurable cantilever displacement and surface stress are 5 nm are 1.3 mN/m respectively. The lowest homocysteine concentration detected with the sensor is 10 muM.