Design and implementation of capacitive micromachined ultrasonic transducers for high intensity focused ultrasound

摘要: High intensity focused ultrasound (HIFU) is a medical procedure for noninvasive treatment of cancers. used to heat and destroy the diseased tissue. Piezoelectricity has been core mechanism generation waves in treatment. Focusing can be done by using spherically curved transducers or lens electronically steering sound phased arrays. Current research HIFU technology targets development MR-guided miniaturized ultrasonic probes cancerous tumors. Capacitive micromachined transducer (CMUT) an alternative generate detect ultrasound. CMUT consists suspended membrane The advances technology, enables fabricating tiny arrays with wide bandwidth makes them strong candidate application. In this thesis, new methodology proposed design operate CMUTs high pressures under continuous wave excitation. An accurate nonlinear circuit model developed carried into SPICE (Simulation Program Integrated Circuit Emphasis) simulator fast simulations. includes radiation impedance array, thus operation fluid environment simulated. verified doing FEM provides novel optimization tool operating non-collapse mode. optimized parameters are presented sample fabrication anodic bonding process. With process, 100 m thick silicon wafer bonded glass substrate. A driving scheme without need DC voltage. Thus, charge trapping problem eliminated. fabricated device 1.8 MPa surface pressure -28dB second harmonic maximum 125V drive voltage at 1.44 MHz which currently state art performance