Plasmonic Absorption Enabled Analyte Detection Using Piezotransistive Microcantilevers

In this work, a highly sensitive photoacoustic (PA) based detection of analytes has been demonstrated using GaN microcantilevers coated with a thin layer of metal nanoparticles (NPs). Microcantilevers were oscillated at their resonance frequencies by a PA excitation generated from a pulsed 520 nm laser, whose amplitude was enhanced by the plasmonic absorption in metal NPs. Analytes such as Hg vapor and H2 altered the plasmonic properties of specific metal NPs, resulting a change in absorption of photons and hence a difference in the generated PA signal strength. Changes in the PA signal is detected with very high sensitivity using an HFET embedded at the base of the microcantilever.