Study of the CMUT operation in microfluidic application

Operation of capacitive micromachined ultrasound transducers (CMUT) in comparatively low profile (2-400 μm) fluid-coupled microchannels was studied by numerical simulation. The two-dimensional transient time finite element analysis was used to simulate the transmission of the short pulse and capture the resulting mechanical waves in solid and fluid environments and at the solid-fluid interface. The analysis of the CMUT cell operation during transmission showed that the bulk waves in fluid, which are reflected from the top wall of the microchannel, can affect the performance of the membrane, if the height of the microchannel is below certain critical value. Membrane swing amplitude and central frequency of membrane oscillations can be shifted because of this interaction. As far as these parameters are informative in sensor applications, the design of the CMUT/microchannel system has to be accounted for the microchannel height.