| Summary: | 碩士 === 國立臺灣大學 === 生醫電子與資訊學研究所 === 107 === Optical imaging systems, such as the two-photon microscope and the light-field microscope, have been widely used to quantify calcium concentration in the cell. However, none of the existing systems can image the calcium concentration deeper than 200 µM due to the limitation of the light penetration depth. The higher resolution and deeper penetration depth can be benefited by exploiting photoacoustics (PA), but the light-absorption limits the measurements of the calcium concentration in the cell. This study investigated the potential improvement of using PA microscopy to measuring calcium concentration by introducing a PA contrast agent (Chlorophosphonazo III, CPZ-III). According to the phantom experiments, a concentration from the range of 25 µM to 2 mM can be successfully measured by using an 8 MHz ultrasound transducer and 150 µM CPZ-III. A 3D calcium-concentration map can be obtained by using the proposed method. The experimental results show that there is a 3-fold improvement on the PA signal, and the tendency concentration is consistent with our expectations. Future works will focus on using GCaMP calcium contrast agent to address the attenuation of the calcium-PA signal.
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