Optical sequential readout of microcantilever arrays for biological detection

A technique for the readout of the nanomechanical response of multiple microcantilevers is presented. This combines the optical beam deflection technique and the scanning of a laser beam illuminating the cantilevers of an array sequentially. The individual motion of each microcantilever is obtained by correlating the total photocurrent collected in a photodetector array, the position of the laser beam and the coordinates of the laser spot centroid on the photodetector. The technique provides sub-angstrom resolution in the cantilever deflection and it allows the readout of tens of cantilevers per second. This is applied for the quasi-simultaneous detection of single-stranded DNA with an array of five microcantilevers. Moreover, this technique also allows the measurement of the resonant frequency of individual microcantilevers into an array. This can be applied for multiple detection of several pathogen targets.