Search

Date of Conference: 7-10 October 2012 We present a design method for airborne capacitive micromachined ultrasonic transducers (CMUT). We use an equivalent lumped element circuit to model both electrical and mechanical properties of CMUT and analyze it in frequency domain using harmonic balance approach. We use this method to design CMUTs for large transmitted power generation at low drive voltage amplitude. We determine the dimensions of an airborne CMUT using the proposed method that works at 30 kHz with 5 mm radius, 240 μm membrane thickness and 11.8 μm effective gap height. The CMUT is designed such that an atmospheric depression of 70% of effective gap height is maintained. © 2012 IEEE.

Date of Conference: 7-10 October 2012 We use an accurate nonlinear equivalent circuit model to analyze CMUT arrays with multiple cells, where every cell in the array is coupled to other cells at their acoustic terminals through a mutual radiation impedance matrix. We get results comparable to finite element analysis accuracy. Hence, the analysis of a large array becomes a circuit theory problem and can be scrutinized with circuit simulators. We study the mutual acoustic interactions that arise through the immersion medium due to the influence of the generated pressure field by each cell on the others. We compare the performance of different 1D cMUT arrays, where each element is half-wavelength wide and 10 and 20 wavelengths long at the resonance frequency of a single cell. © 2012 IEEE.

Date of Conference: 7-10 October 2012 An equivalent electrical circuit model valid for collapsed mode operation of CMUT is described. The across and through variables of the circuit model are chosen to be rms force and rms displacement over the surface of the CMUT membrane. The relation between rms displacement and applied voltage is obtained through analytical calculations utilizing the exact force distribution. The radiation impedance of collapsed mode CMUT is included as a load impedance in the circuit model. The resulting equivalent circuit is merged with uncollapsed mode model, to obtain a simulation tool that covers the whole operation range of CMUT. © 2012 IEEE.