Dielectric antenna effects in integrating line piezoelectric sensors for optoacoustic imaging

TL;DR

This paper investigates dielectric antenna effects in water-immersed piezoelectric sensors for optoacoustic imaging, demonstrating a low-cost shielding solution that enhances signal-to-noise ratio and system sensitivity.

Contribution

It reveals dielectric antenna effects in water-immersed sensors and introduces a silver-paint shield to mitigate noise without compromising acoustic performance.

Findings

Dielectric antenna effects limit sensor performance due to electromagnetic noise.

Silver-paint shielding significantly improves signal-to-noise ratio.

Enhanced noise reduction enables use of higher gain amplifiers.

Abstract

This work studies the adverse effects, as regards noise, of immersing in water an integrating line piezoelectric detector devoted to optoacoustic imaging. We found that the sensor, in conjunction with the acoustic coupling medium (water), behaves as a resonant dielectric antenna. This phenomenon limits the performance of the system because it efficiently captures unwanted electromagnetic signals. The requirement of good acoustic coupling between the water and the sensor precluded the use of a standard metallic shielding enclosure. Therefore, we resorted to a silver-paint based electrical shield deposited on the detector. This easy-to-implement and low-cost solution significantly increases the signal to noise ratio and does not degrade the acoustic performance. The noise reduction allows the use of a better transimpedance amplifier with higher gain and bandwidth; thus achieving a very sensitive, low-noise detection system.