Non-Contact High-Resolution All-Optical Handheld Ultrasound Imaging System

We set out in the Phase I program to design a handheld, non-contact laser ultrasound (ncLUS) imager for aiding combat medics’ fast triaging on injured Warfighters in the battlefield. The ncLUS imager is to enable rapid assessments on conditions of internal hemorrhage and presence of foreign objects like shrapnel fragments through ultrasound imaging, all in non-contact manner and with the desired device form factor similar to recent generation of smart phones. By leveraging the device principles of (1) optical excitation of ultrasound waves in human tissues, (2) optical detection of back-scattered ultrasound waves on human skin surface and, (3) skin pigment and skin surface condition independent photodetection, several iterations of ncLUS imager designs were developed in the Phase I program, with successively reduced device dimensions and added functionalities. As of the end of the Phase I program (March 2022), the latest ncLUS imager design supports the dimensions of 77 mm x 190 mm x 35 mm. It also supports a wide range of operational capabilities ranging from eye-safe operation, auto-scanning, supports variable standoff distance between the ncLUS imager and the injured Warfighter’s body surface, near-infrared (NIR) camera for targeting the evaluation area as well as standoff distance measurement, body surface contour/topography compensation and image correction, as well as a large liquid crystal display (LCD) for aiming the ncLUS and displaying the reconstructed ultrasound images. Design details on the various laser sources, optics, and the associated optomechanical mounts have been identified. Also included in the Phase I activity involve the detailed design work on various electronics that maintains the proper function of the ncLUS imager, electrical power supply and management, wi-fi communication with external devices. When combined with the ultrasound image reconstruction algorithms developed in the Phase I program, the electronic circuit boards are also developed to support reconstruction and presentation of the ultrasound images on the LCD display of the ncLUS imager. A number of pathways to further device miniaturization will be considered in the Phase II program and they include (1) custom-build of miniaturized laser sources, (2) use of ½” optics in the ncLUS imager and, (3) deployment of micro-electro-mechanical system (MEMS) mirror scanner and photo-detector array. The resultant ncLUS imager device thickness has been preliminarily determined to be 28 mm and 17 mm, respectively, for the ½”-optics option and the MEMS scanner approach. Prototype ncLUS imager will be built and delivered to the Government. Lab based tests using grocery meats and demonstration on human subjects will be pursued after relevant IRB clearance. Two visits are also proposed to the Army Medic School for demonstrating the ncLUS imager to combat medics.