Imec, a leading research and innovation hub in Belgium, has demonstrated an optomechanical ultrasound sensor on a silicon photonic chip that has an unprecedented sensitivity due to an innovative optomechanical waveguide.
By leveraging this high-sensitivity waveguide, Imec's 20-µm small sensor has a detection limit two orders of magnitudes better than piezoelectric elements of identical size.
Potential clinical and biomedical applications of ultrasonic and photoacoustic imaging include deep-tissue mammography and the study of vascularization or innervation of potential tumorous tissue.
“The sensor we have demonstrated will be a gamechanger for deep tissue imaging in otherwise non-transparent tissues such as skin or brain. For applications such as sub-cutaneous melanoma imaging or mammography, it enables a more detailed view of the tumor and vascularization around, aiding in a more detailed diagnosis,” says Xavier Rottenberg, fellow wave-based sensors and actuators at imec.
Imec said its solution is based on a highly sensitive split-rib optomechanical waveguide fabricated using new CMOS-compatible processing. The sensitivity is two orders of magnitude larger than a state-of-the-art device. A low detection limit can improve the trade-off between imaging resolution and depth for ultrasound applications, and is crucial for photoacoustic imaging, where pressures are up to three orders of magnitude lower than in conventional ultrasound imaging techniques.
Finally, a fine-pitched (30 µm) matrix of these tiny (20 µm) sensors can be easily integrated on-chip with photonic multiplexers. This opens the possibility of new applications such as miniaturized catheters because the sensor matrices require only few optical fibers to be connected instead of one electrical connection per element in the case of piezoelectric sensors.
