Ryerson University, Department of Physics, Toronto, Ontario, CanadabInstitute for Biomedical Engineering, Science and Technology (iBEST), Ryerson University and St. Michaels Hospital, Toronto, ON, CanadacKeenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.
J Biomed Opt. 2017 Apr 1;22(4):46001. doi: 10.1117/1.JBO.22.4.046001.
An inexpensive noncontact photoacoustic (PA) imaging system using a low-power continuous wave laser and a kilohertz-range microphone has been developed. The system operates in both optical and PA imaging modes and is designed to be compatible with conventional optical microscopes. Aqueous coupling fluids are not required for the detection of the PA signals; air is used as the coupling medium. The main component of the PA system is a custom designed PA imaging sensor that consists of an air-filled sample chamber and a resonator chamber that isolates a standard kilohertz frequency microphone from the input laser. A sample to be examined is placed on the glass substrate inside the chamber. A laser focused to a small spot by a 40 × objective onto the substrate enables generation of PA signals from the sample. Raster scanning the laser over the sample with micrometer-sized steps enables high-resolution PA images to be generated. A lateral resolution of 1.37 ?? ? m was achieved in this proof of concept study, which can be further improved using a higher numerical aperture objective. The application of the system was investigated on a red blood cell, with a noise-equivalent detection sensitivity of 43,887 hemoglobin molecules ( 72.88 × 10 ? 21 ?? mol or 72.88 zeptomol). The minimum pressure detectable limit of the system was 19.1 ?? ? Pa . This inexpensive, compact noncontact PA sensor is easily integrated with existing commercial optical microscopes, enabling optical and PA imaging of the same sample. Applications include forensic measurements, blood coagulation tests, and monitoring the penetration of drugs into human membrane.
已开发出一种使用低功率连续波激光和千赫兹范围麦克风的廉价非接触式光声（PA）成像系统。该系统在光学和 PA 成像模式下运行，旨在与传统的光学显微镜兼容。检测 PA 信号时不需要水合耦合液；空气用作耦合介质。PA 系统的主要组件是一个定制设计的 PA 成像传感器，它由一个充满空气的样品室和一个隔离标准千赫兹频率麦克风与输入激光的谐振室组成。要检查的样品放在腔室内的玻璃基板上。通过 40×物镜将激光聚焦到基板上的小光斑，可从样品中产生 PA 信号。以微米级的步长对样品进行激光光栅扫描，可生成高分辨率的 PA 图像。在这项概念验证研究中，实现了 1.37??m 的横向分辨率，使用更高数值孔径的物镜可以进一步提高分辨率。该系统的应用已在红细胞上进行了研究，其噪声等效检测灵敏度为 43,887 个血红蛋白分子（72.88×10-21??mol 或 72.88 zeptomol）。该系统的最小可检测压力为 19.1??Pa。这种廉价、紧凑的非接触式 PA 传感器易于与现有的商业光学显微镜集成，可实现对同一样品的光学和 PA 成像。应用包括法医测量、血液凝固测试以及监测药物渗透入人体膜。
