We demonstrate the use of an astigmatic detection system (ADS) for resonance frequency identification of polymer microcantilever sensors. The ADS technology is based on a DVD optical head combined with an optical microscope (OM). The optical head has a signal bandwidth of 80 MHz, allowing thermal fluctuation measurements on cantilever beams with a subnanometer resolution. Furthermore, an external excitation can intensify the resonance amplitude, enhancing the signal- to-noise ratio. The full width at half maximum (FWHM) of the laser spot is 568 nm, which facilitates read-out on potentially submicrometer-sized cantilevers. The resonant frequency of SU-8 microcantilevers is measured by both thermal fluctuation and excited vibration measurement modes of the ADS.
Hwu, E-T., Liao, H-S., Bosco, F., Chen, C-H., Keller, S. S., Boisen, A., & Huang, K-Y. (2012). An Astigmatic Detection System for Polymeric Cantilever-based Sensors. Journal of Sensors, 580939. https://doi.org/10.1155/2012/580939