Dimensional scaling for optimized CMUT operations

This work presents a dimensional scaling study using numerical simulations, where gap height and plate thickness of a CMUT cell is varied, while the lateral plate dimension is adjusted to maintain a constant transmit immersion center frequency of 5 MHz. Two cell configurations have been simulated, one with a single square cell and one with an infinite array of square cells. It is shown how the radiation impedance from neighboring cells has a significant impact on the design process. For transmit optimization, both plate dimensions and gap height should be increased. For receive mode, the gap height should be increased while the effect of plate dimensions is ambiguous depending on if the array design is closest to a single cell or infinite array of cells. The findings of the simulations are verified by acoustical measurements on two CMUT arrays with different plate dimensions.