Improved Evaluation of CMUT Collapse and Snapback Voltages via Charge Control using Fast Dynamic Current Excitation

This work describes a method to estimate the mean collapse and snapback voltages of CMUT elements and their statistical distribution by extracting the voltage-dependent capacitance from fast dynamic excitation of the device, enabling fast analysis of fabrication-related intra-element and inter-element variability. While both voltage excitation and current excitation of the CMUT element provide comparable array-level results in terms of mean and deviation of positive and negative collapse and snapback voltages, it is demonstrated that improved detection of isolated collapse and snapback events is achieved through current-driven excitation, implementing charge-controlled actuation of the membranes.