2-step surface modification technology for acoustic chemical sensor arrays based on CMUTs

A new method has been developed to allow a localized deposition of different sensitive materials on the surface of capacitive micromachined ultrasonic transducers (CMUTs). It is based on a 2-layer preparation. In the first step, nanoparticles provide a bottom layer which defines the acoustic properties of the device, while different supermolecules are dispensed onto selected areas of the nanoparticle layer in the second step. This layer serves as chemically sensitive interface. The fairly ordered arrangement of the nanoparticles guarantees a sufficient uniformity of the sensitive film. The chemically modified CMUT wafers were exposed to toluene and n-propanol vapors.