Improving PMUT Receive Sensitivity via DC Bias and Piezoelectric Composition

Area of Science:

• Materials Science
• Acoustics
• Electrical Engineering

Background:

• Lead zirconate titanate (PZT) piezoelectric micromachined ultrasound transducers (PMUTs) are crucial for various sensing applications.
• The receive sensitivity of PMUTs is primarily determined by their voltage piezoelectric coefficient (h).
• Optimizing PMUT performance is essential for advancing ultrasound technology.

Purpose of the Study:

• To investigate the effect of DC bias on the performance of PZT-based PMUTs.
• To enhance the receive sensitivity and photoacoustic signal detection of PMUT devices.
• To evaluate the impact of DC bias on B-mode photoacoustic imaging.

Main Methods:

• Applied DC biases up to 15 V to a 2 μm PbZr0.52Ti0.48O3 film within PMUTs.
• Measured changes in the in-plane charge coefficient (e31,f), permittivity, and voltage coefficient.
• Evaluated ultrasound receive sensitivity and photoacoustic signal strength in released PMUT devices.
• Conducted B-mode photoacoustic imaging experiments to assess signal clarity and imaging depth.

Main Results:

• Applied DC bias increased the in-plane charge coefficient (e31,f) by 1.6 times and the voltage coefficient by approximately 2.5 times.
• Permittivity decreased by a factor of 0.6 with applied DC bias.
• Ultrasound receive sensitivity improved by 2.5 times, and photoacoustic signal strength improved by 1.9 times with a 15 V DC bias.
• B-mode photoacoustic imaging demonstrated clearer signals and an increased imaging depth (4.3 cm vs. 3.7 cm) with DC bias.

Conclusions:

• Applying DC bias is an effective method to significantly improve the receive sensitivity of PZT-based PMUTs.
• DC bias optimization enhances photoacoustic signal detection and imaging performance.
• This technique offers a practical approach to boost the capabilities of PMUTs for advanced sensing and imaging.