High-resolution silicon photonics focused ultrasound transducer with a sub-millimeter aperture

Abstract

We present an all-optical focused ultrasound transducer with a sub-millimeter aperture and demonstrate its capability for high-resolution imaging of tissue ex vivo. The transducer is composed of a wideband silicon photonics ultrasound detector and a miniature acoustic lens coated with a thin optically absorbing metallic layer used to produce laser-generated ultrasound. The demonstrated device achieves axial resolution and lateral resolutions of 12 μm and 60 μm, respectively, well below typical values achieved by conventional piezoelectric intravascular ultrasound. The size and resolution of the developed transducer may enable its use for intravascular imaging of thin fibrous cap atheroma.

Silicon photonic acoustic detector (SPADE) using a silicon nitride microring resonator

“…In the case of intravascular imaging [41] , acoustic focusing capabilities would need to be added to MRR-SPADE, which may be achieved by bonding the sensor to an acoustic lens, as demonstrated in Refs. [42] , [43] , or by utilizing larger microrings, which exhibit a needle-shaped focus [44] , [45] , [46] .…”

Miniaturised dual-modality all-optical ultrasound probe for laser interstitial thermal therapy (LITT) monitoring

“…Among these sensors, plano-concave resonators with high detection sensitivity and broad detection bandwidth, which can detect the acoustically induced deformations of its polymer cavity, are well-suited for minimally invasive procedures [ 28 ]. In previous works, the OpUS devices have been used successfully to achieve two- and three-dimensional imaging on ex vivo tissue [ 12 , 29 , 30 ], as well as in vivo real-time imaging [ 11 , 31 ]. Additionally, side-viewing devices have been developed for rotational imaging [ 32 , 33 ] and two-dimensional imaging in which the transmitter and receiver were combined onto a single optical fibre for further miniaturisation [ 14 , 34 ].…”