Fig. 3: Characterization of the CSPM. | Nature Communications

Fig. 3: Characterization of the CSPM.

From: A conformal piezoelectric microsystem for demographic-adaptive and calibration-free cuffless blood pressure monitoring

Fig. 3: Characterization of the CSPM.

a Impedance and phase angle spectra of the ultrasound transducer, showing good electromechanical coupling capability. b Resonance and antiresonance frequency variations of 8 transducer elements in CSPM. The mean values/SDs are 5.07 MHz/43.76 kHz (resonant) and 5.74 MHz/70.62 kHz (antiresonant), respectively. c Acoustic field simulation of ultrasound transducer with different sizes. d Pulse-echo response and frequency spectra, with a short spatial pulse length (~1.32 μs) with a peak to peak voltage of ~1.6 V, and a central frequency of 5.11 MHz with good sensitivity of 31% at −6 dB bandwidth. e Electrical impedances of ultrasound sensor under different strains. f Comparison of PWF sensor without and with cavity in terms of response time. g Square wave displacement loads with varying amplitudes applied on PWF sensor. h Square response of PWF sensor, showing a consistent trend with displacement loads. i, j Sensitivity test results for the stacked-type PWF sensor and cantilever-type PWF sensor, which are 0.20 V/N and 32.43 V/N, respectively, with coefficients of determination of 0.99 and 0.98 respectively.

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