Non-contact photoacoustic initial pressure imaging

光学吸收是一种理想的成像对比，因为各种各样的生物医学和工业目标吸收光；这些包括但不限于RNA、DNA、血液、碳纤维、金属和一些气体分子，如二氧化碳和乙烯。光声（PA）技术可以提供无标记（无外部染料）和直接测量深散射介质（即组织）中的光吸收。然而，传统的PA结构需要与样品进行物理声学耦合（即使用超声凝胶接触）。在生物医学应用中，开放的组织接触（即伤口愈合）会引起疼痛、不适和潜在的感染。此外，对于某些工业用途，如敏感材料（即薄膜）的无损检测，接触是不可取的。***针对这些缺点，PI首创了一种独特的PA技术，可以直接测量组织和其他介质深处的光声初始压力，而无需表面接触。光声遥感（PARS）显微技术在穿透深度和灵敏度方面显示出巨大的潜力。它展示了在散射介质中以微米级分辨率和光学吸收对比度成像2.5毫米深度的能力，这是其他成像技术无法实现的。然而，在将该技术应用于临床或工业环境之前，还需要进行大量的基础研究。拟议的研究计划将解决该技术的基本限制，如缓慢的3D成像和弱的功能成像灵敏度。总体目标是推动技术的性能界限超越目前的可能。具体而言，该团队将：(i)开发模型并研究超灵敏方法，将灵敏度推至物理极限（射击噪声极限）；（ii）研究强大的多波长激发源，以提高功能和分子对比可视化能力；（iii）探索深度分辨率传感方法，实现快速3D成像。***拟议的研究将最终解决光学传感界对高灵敏度无标签非接触式高分辨率实时3D光学吸收成像方式的长期需求。反过来，这将为生物医学成像和工业传感等一系列科学领域的新研究方法奠定基础。无接触光学成像和无损检测的潜力将有助于推动对加拿大具有战略重要性的部门的创新。参与这个多学科项目的学生将获得必要的技能和专业知识，成为这些行业的未来领导者，包括生物医学和医疗设备，国防和工业传感，在国际范围内创造竞争优势。除了经济效益，准确的检测和诊断工具将帮助加拿大人过上更安全、更健康、更快乐的生活

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.**