Heating of Polymer Films Induced by HIFU: Study of Acoustic and Thermal Effects

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Coralie Koo Sin Lin - , Robert Bosch GmbH (Author)
  • Lukas Oehm - , Fraunhofer Institute for Process Engineering and Packaging (Author)
  • Marko Liebler - , Robert Bosch GmbH (Author)
  • Holger Brehm - , Robert Bosch GmbH (Author)
  • Klaus Vitold Jenderka - , Merseburg University of Applied Sciences (Author)
  • Jens Peter Majschak - , Chair of Processing Machines/ Processing Technology, Fraunhofer Institute for Process Engineering and Packaging (Author)

Abstract

This article presents the study of the thermal and acoustic effects occurring in polymer samples of different thicknesses receiving high-intensity focused ultrasound (HIFU). Whereas the heating mechanisms in polymer plates immersed in water are well known, the physical mechanisms enabling the heating of polymer films using a solid waveguide transducer remain not fully understood. A coupled acoustothermal finite-element simulation is conducted to model the sound field and the heat generation inside polymer samples of different thicknesses. To validate the acoustic model, the acoustic particle velocities at the transducer waveguide tip are measured by vibrometry and compared with the simulation results. The heating effects in the samples are monitored using an infrared thermography system and compared with the measured particle velocities and with the acoustic and thermal simulation results. Correlations among particle velocities, sound intensity, and polymer heating are investigated. A qualitative and quantitative correlation between the simulation and the measurement results is found. Experiments show that the heating effects depend on the sample thickness. In samples thinner than 1 mm, the maximum temperature is lower than the one observed in samples thicker than 1 mm but rises faster. The simulation shows that the sound intensity in polymer samples thinner than 1 mm decreases sharply with the decrease in the thickness of the sample. This study contributes to the understanding of the challenges in heating thin polymer films by HIFU in a dry environment, using only a force to couple the transducer to the polymer films.

Details

Original languageEnglish
Article number8832263
Pages (from-to)1201-1209
Number of pages9
JournalIEEE transactions on ultrasonics, ferroelectrics, and frequency control
Volume67
Issue number6
Publication statusPublished - Jun 2020
Peer-reviewedYes

External IDs

PubMed 31514132

Keywords

Keywords

  • Finite element analysis, interferometry, polymer film, temperature measurement, ultrasonic transducer, waves propagation