Thermometric profiling of capacitive micromachined ultrasonic transducer surface via micro-fabricated fractal resistive thermometer

Conventional High-Intensity Focused Ultrasound (HIFU) systems typically utilize lead zirconate titanate (PZT) transducers, which are limited by their modest thermal conductivity and inefficient heat dissipation. Capacitive Micromachined Ultrasonic Transducers (CMUTs), with significantly higher thermal conductivity due to their silicon composition (~150 Wm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup>K<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup>), present a promising alternative, offering improved thermal dissipation and reduced self-heating. Despite these advantages, there has been a lack of quantitative data on CMUTs' thermal behavior, leaving uncertainties regarding their efficacy in addressing thermal challenges during HIFU operations. To close this gap, our study introduces a novel method to assess the thermal attributes of CMUTs by integrating a micro-fractal resistive temperature detector (µ-FRTD) directly onto the CMUT surface. By employing a fractal design for the µ-FRTD, we enhance sensor performance and strain tolerance (stretch capabilities exceeding 10 %), enabling accurate thermal monitoring and energy dissipation analysis during CMUT operation. The temperature rise within CMUT is observed to reach a maximum of 4.59 K. This approach provides valuable insights into CMUTs' potential for improved thermal management in HIFU applications.