Miniature all-optical flexible forward-viewing photoacoustic endoscopy probe for surgical guidance

Abstract

A miniature flexible photoacoustic endoscopy probe that provides high-resolution 3D images of vascular structures in the forward-viewing configuration is described. A planar Fabry–Perot ultrasound sensor with a bandwidth of 53 MHz located at the tip of the probe is interrogated via a flexible fiber bundle and a miniature optical relay system to realize an all-optical probe measuring 7.4 mm in outer diameter at the tip. This approach to photoacoustic endoscopy offers advantages over previous piezoelectric based distal-end scanning probes. These include a forward-viewing configuration in widefield photoacoustic tomography mode, finer spatial sampling (87 µm spatial sampling interval), and wider detection bandwidth (53 MHz) than has been achievable with conventional ultrasound detection technology and an all-optical passive imaging head for safe endoscopic use.

Photoacoustic imaging for monitoring of stroke diseases: A review

“…Nowadays, with the technological evolution, devices including amplifiers, digital-analog converters, controllers, and even sensors, can be combined with integrated circuits to decrease the size and cost of the system [ 149 ]. Developing an all-optical PAI system that replaces the piezoelectric scanning probes is another direction to provide wider bandwidth, finer spatial sampling [ 150 ]. The research on flexible materials can promote the design of emitters and sensors to better cover the detecting surface [ 151 ].…”

Perspective on fast-evolving photoacoustic tomography

“…In addition to 2D ultrasound transducer arrays based on piezoelectric materials, optical ultrasound detectors, such as the Fabry–Perot interferometer, 58 , 59 micro-ring resonator, 60 and Bragg grating fiber, 61 – 63 have been actively explored for volumetric PACT. Compared with piezoelectric transducers, optical ultrasound detectors often have smaller size ( ), larger detection bandwidth and receiving angle, higher detection sensitivity per unit area, better transmittance of the PA excitation light, and simpler PA signal readout, all of which can help improve the resolution and penetration depth of volumetric PACT.…”

Advances in Endoscopic Photoacoustic Imaging

“…Apart from the above conventional piezoelectric materials and their composites, new materials and technologies are emerging in PA/US endoscopy, including lead free piezoelectric materials [80], micromachine based US transducers (piezoelectric and capacitive micromachined US transducer, PMUT and CMUT) [81][82][83][84][85][86], and optical based acoustic sensing [87]. They have their own unique advantages, but further developments are still required to prove their practical capabilities in PA/US endoscopy.…”