The thermoelastic effect in a black polydimethylsiloxane (PDMS) film is used to produce high-frequency, high-intensity ultrasound for applications in water and soft tissue. We show that the optoacoustic transduction efficiency is improved by about 10 dB by decreasing the thickness of the black PDMS film from 25 μm to 11 μm. The center frequency of the generated ultrasound is 60 MHz, with a -6 dB bandwidth of 80%. When a 5 ns laser pulse with energy of 50 μJ is delivered to a spot size of 25 μm, the acoustic pressure 10 mm away from the film surface is about 800 kPa. Furthermore, we demonstrate that the center frequency and bandwidth of the generated ultrasound is mainly determined by the temporal profile of the input optical pulse, and it has the potential to be easily improved to above 100 MHz.
|Original language||English (US)|
|Number of pages||5|
|Journal||IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control|
|State||Published - Mar 2007|
Bibliographical noteFunding Information:
Manuscript received April 27, 2006; accepted October 24, 2006. This work was supported in part by NIH under grants EB-003455 and EB-003449. The authors are with the Departments of Electrical Engineering & Computer Science and Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109-2099 (e-mail: email@example.com). Digital Object Identifier 10.1109/TUFFC.2007.292