Flexible transparent CMUT arrays for photoacoustic tomography
Mahyar Ghavami, Afshin Kashani Ilkhechi, Roger J. Zemp
Abstract
This paper reports the fabrication and characterization of the first flexible transparent capacitive micromachined ultrasound transducer (CMUT) array for through-illumination photoacoustic tomography. Fabricated based on an adhesive wafer bonding technique and a PDMS backfill approach, the array has a maximum transparency of 67% in visible light range and can be bent to a radius of curvature of less than 5 mm without the structural layers being damaged. With a center frequency of 3.5 MHz, 80% fractional bandwidth, and noise equivalent pressure (NEP) of 62 mPa/ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msqrt> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">H</mml:mi> <mml:mi mathvariant="normal">z</mml:mi> </mml:mrow> </mml:msqrt> </mml:math> , the array was successfully used in limited-view photoacoustic tomography of a 100 µ m wire target, demonstrating lateral and axial resolutions of 293 µ m and 382 µ m, respectively, with 46 dB signal-to-noise ratio. Additionally, deep tissue photoacoustic tomography was also demonstrated on a blood tube within a chicken tissue using the fabricated CMUT arrays.