Fig. 3: Characterization of snCMUT.
From: Silicon nanocolumn-based disposable and flexible ultrasound patches
Electrical impedance measurements of the corresponding element of the snCMUT: the phase part (a) and the amplitude part (b). The electrical impedance was measured using different bias voltages, 10 to 50 V of DC. Phase shifts with bias voltage were observed. The resonant frequency in air was 6.7 MHz at 50 V of bias. c The dynamic plate displacement of the snCMUT measuring from a laser Doppler vibrometer. The maximum displacement was measured in the four-piston top plate’s positive (left) and negative (right) direction. d The maximum peak-to-peak displacement of the four-piston top plate. e Comparison of the displacement profile of the moving top plate between conventional CMUT and snCMUT. The measured displacement profile is from the red dashed line in (d). The bias voltage of each CMUT is 48% of the pull-in voltage. Even though there are variations in the maximum displacement of each piston top plate, the embedded silicon nanocolumn induces parallel motion of the top plate in CMUT, which causes enhanced average displacement. f Measured acoustic pressure of the snCMUT via hydrophone as follows a number of operating elements at a distance of 3.5 mm in corn oil. g Impulse response (16.6 ns, 20VPP) and its Fourier transform of a snCMUT array element under dc bias of 50 V measured by hydrophone in corn oil. h 39 dB amplified pulse-echo impulse response (16.6 ns, 20 VPP) and its Fourier transform of a snCMUT array element under DC bias of 50 V reflected on ultrasound gel pad and air interface.
