Non-contact photoacoustic initial pressure imaging

点击翻译按钮获取中文摘要

Optical absorption is a desirable imaging contrast since a wide variety of biomedical and industrial targets absorb light; these include but are not limited to RNA, DNA, blood, carbon fibers, metals and some gas molecules such as CO2 and ethylene. Photoacoustic (PA) techniques can provide a label-free (no external dyes) and direct measurement of optical absorption in deep scattering media (i.e., tissue). However, conventional PA architectures require physical acoustic coupling (i.e., contact using ultrasound gel) with the sample. In biomedical applications, open tissue contact (i.e., wound healing) can cause pain, discomfort, and potentially infection. Also, for some industrial uses, such as non-destructive testing of sensitive materials (i.e., thin films), contact is not desirable. In response to these shortcomings, the PI pioneered a unique PA technology that can directly measure photoacoustic initial pressure deep within tissues and other media without surface contact. Photoacoustic remote sensing (PARS) microscopy has shown great potential regarding penetration depth and sensitivity. It demonstrated the ability to image to depths of 2.5 mm in scattering media with micron-scale resolution and optical absorption contrast, something that no other imaging techniques can achieve. However, significant fundamental research is required before the technology can be deployed in a clinical or industrial setting. The proposed research program will address the fundamental limitations of the technology, such as slow 3D imaging and weak functional imaging sensitivity. The overarching aim is to push the technology's performance boundaries beyond what is currently possible. Specifically, the team will: (i) develop models and research ultra-sensitive methods to push the sensitivity to the physical limit (shot-noise limited) ; (ii) investigate powerful multi-wavelength excitation sources to improve functional and molecular contrast visualization capabilities; and (iii) explore depth-resolved sensing methods to enable fast 3D imaging. The proposed research will ultimately address a long--standing demand within the optical sensing community for a highly sensitive label-free non-contact high-resolution real-time 3D optical-absorption imaging modality. This will, in turn, lay the foundation for new research approaches within a range of scientific fields, such as biomedical imaging and industrial sensing. The potential for contact-free optical imaging and non-destructive testing will help drive innovation in sectors of strategic importance to Canada. Students involved in this multidisciplinary program will gain the necessary skills and expertise to become future leaders within these industries, including biomedical and healthcare devices, defence, and industrial sensing, creating a competitive advantage within the international context. Beyond economic benefit, accurate detection and diagnostic tools will help Canadians live safer, healthier and happier lives.