The current amplifier is exploiting and integrated with the CMUT cells to minimize the parasitic capacitance and enhance the sensitivity of the overall ultrasonic system.
We inflict a waterproof package for CMUT chip and measured in the underwater environment.
4: The cross section view of the CMUT structure, (A) Before post Processing (B) After post processing
CMUT devices, largely used, for instance, in biomedical imaging , transduce ultrasound waves into electrical signal by means of the flexure of a thin (~200 nm) micro-machined membrane.
This is the fundamental reason why the minimization of the length of the connection between the electrodes and the amplifier pad is so important, leading to the radical solution of making the experiment/sensor "on the pad," that is, building the sensing microelectrodes on the same ASIC substrate, as shown for MEMS gyros , CMUT , dust detection , on-chip capacitive biosensors , and nanopore current amplifier  and AFM impedance spectroscopy on pad .
High-frequency, high-resolution transducers are potentially easier to fabricate with CMUT technology, which could make ultrasound available for a wider range of applications.
The development of CMUT technology was initiated many years ago by a team at Stanford University that included the Kolo Medical founders.
The devices are known as capacitive micromachined ultrasound transducers, or CMUTs
Unlike the piezoelectric IDTs, where a pair of the surface electrodes establish one finger of the transducer, CMUT interdigital transducers need only one surface electrode, since another one is at the bottom of the device.
Design of the microstructure of the interdigital CMUT is shown on the Fig.
This research was also designated to test the proprietary CMUT fabrication technology , .
CMUT operating point can be found from the lumped element model subjected to electrostatic and spring force equilibrium, which can be stable and unstable.