Electro-optically based liquid mass sensor using resonating micro-plate under harsh drop and spray conditions

We perform in-situ sensing of volatile droplet and spray masses using plate-like single crystal Si micro-resonators with low stress, where robust and reusable operation was attained over harsh conditions and over multiple cycles. A home-built electro-optical sensing system has been used. The effects on the resonant frequency of altered mass loading, elasticity and strain are compared, where the latter two mechanisms are found to be negligible in the presence of low viscosity liquids deposited on top of our devices. In resonant mode, the loaded mass is estimated from measured frequency response shifts and interpreted from simple (uniformly deposited film) model.