Silicon-photonics acoustic detector for optoacoustic micro-tomography

High-resolution photoacoustic tomography is challenging due to reduced efficiency of miniaturized piezoelectric elements. Here, the authors fabricate a miniaturized silicon-photonics acoustic detector coated with a sensitivity-enhancing elastomer, and demonstrate high-resolution in vivo imaging. Medical ultrasound and optoacoustic (photoacoustic) imaging commonly rely on the concepts of beam-forming and tomography for image formation, enabled by piezoelectric array transducers whose element size is comparable to the desired resolution. However, the tomographic measurement of acoustic signals becomes increasingly impractical for resolutions beyond 100 mu m due to the reduced efficiency of piezoelectric elements upon miniaturization. For higher resolutions, a microscopy approach is preferred, in which a single focused ultrasound transducer images the object point-by-point, but the bulky apparatus and long acquisition time of this approach limit clinical applications. In this work, we demonstrate a miniaturized acoustic detector capable of tomographic imaging with spread functions whose width is below 20 mu m. The detector is based on an optical resonator fabricated in a silicon-photonics platform coated by a sensitivity-enhancing elastomer, which also effectively eliminates the parasitic effect of surface acoustic waves. The detector is demonstrated in vivo in high-resolution optoacoustic tomography.

Automated summary

The authors demonstrate high-resolution in vivo optoacoustic tomography using a miniaturized silicon-photonics acoustic detector coated with a sensitivity-enhancing elastomer. This detector allows for tomographic imaging with spread functions narrower than 20 μm and eliminates the parasitic effect of surface acoustic waves. The miniaturized detector provides higher resolution compared to piezoelectric array transducers commonly used in medical ultrasound and optoacoustic imaging.