Sensing light and sound velocities of fluids in 2D phoxonic crystal slab

We study theoretically the potentiality of dual phononic-photonic (the so-called phoxonic) crystals for sensing applications. In this work, we study the transmission normal to a periodically perforated silicon slab when the surrounding medium is a liquid. We investigate the existence of well-defined features (peaks or dips) in the transmission spectra of acoustic and optical waves and estimate their sensitivity to the sound and light velocities of the liquid environment. Such ultra compact structure is shown to be a label-free, affinity-based acoustic and optical nanosensor, useful for biosensing applications.