Improving PMUT Receive Sensitivity via DC Bias and Piezoelectric Composition

Abstract

The receive sensitivity of lead zirconate titanate (PZT) piezoelectric micromachined ultrasound transducers (PMUTs) was improved by applying a DC bias during operation. The PMUT receive sensitivity is governed by the voltage piezoelectric coefficient, h31,f. With applied DC biases (up to 15 V) on a 2 μm PbZr0.52Ti0.48O3 film, e31,f increased 1.6 times, permittivity decreased by a factor of 0.6, and the voltage coefficient increased by ~2.5 times. For released PMUT devices, the ultrasound receive sensitivity improved by 2.5 times and the photoacoustic signal improved 1.9 times with 15 V applied DC bias. B-mode photoacoustic imaging experiments showed that with DC bias, the PMUT received clearer photoacoustic signals from pencil leads at 4.3 cm, compared to 3.7 cm without DC bias.

Review of Piezoelectric Micromachined Ultrasonic Transducers for Rangefinders

“…Therefore, the product of the sensitivities can be described by , which is denoted as the figure of merit for a pMUT [ 80 ]. Since larger give rise to a smaller maximum range error or larger maximum range according to Equation (10), researchers have been working on choosing different piezoelectric materials and strategies to enhance by increasing the absolute value of or decreasing in order to enlarge the maximum range of pMUT rangefinders [ 81 , 82 , 83 ].…”

Temperature dependence of dielectric nonlinearity of BaTiO3 ceramics

“…This produces a far stronger DC bias dependence of the relative permittivity [4] than would be predicted based on phenomenological descriptions of the field dependence of the intrinsic permittivity (e.g., intrinsic dielectric stiffening) [17,18] . This progressive loss of the extrinsic contributions to the permittivity is problematic in multilayer ceramic capacitors where the voltage saturation significantly depresses the usable capacitance [19] . In contrast, the suppression is very helpful in some piezoelectric sensing applications, as it increases the figure of merit = piezoelectric coefficient/relative permittivity [20] .…”

Curved and Annular Diaphragm Coupled Piezoelectric Micromachined Ultrasonic Transducers for High Transmit Biomedical Applications

“…Feng et al [30] proposed a pMUT integrated with a volume-tunable Helmholtz resonator, realizing a 200% sound pressure level (SPL) increase and two-fold bandwidth enhancement in the experiments. Cheng et al [31] enhanced the receive sensitivity of the pMUT by applying a DC bias during operation, improving sensitivity by a factor of 2.5 using a 15 V DC bias. Thereafter, Xu et al [17] proposed a pMUT structure combing annular and circular diaphragms, resulting in an output pressure increase of 155% compared with that generated by the circular reference.…”