Gas bubbles induced by combined optical and ultrasound energies for high-resolution deep optical microscopy

Ultrasound-induced optical clearing microscopy (US-OCM) addresses limited imaging depth in optical microscopy, caused by light scattering in biological tissues. It uses ultrasound-induced gas bubbles to better image biological samples. However, controlling the bubble location using only ultrasound is challenging. This study introduces a novel method, “optrasound,” combining optical and ultrasound energies for precise bubble control. It presents the ultrasound field and uses a focused laser to trigger bubble formation. Optrasound-induced deep microscopy improves light beam width by 3.39 times at a depth of 350 µm because the gas bubbles reduce light scattering. This technique can precisely localize a bubble cloud while matching the US-OCM performance.