This work explores the use of quantitative photoacoustic microscopy to map the concentrations of methylene blue in agar phantoms. Our investigation covers wavelengths from 700 nm to 750 nm and looks at concentrations of 5 mM, 10 mM, and 15 mM. Through a detailed investigation of the photoacoustic response, the multi-wavelength method provides information about molecule distributions. Our results highlight this methodology’s potential for accurate concentration mapping, with prospective applications in the clinical and biological areas. By giving a systematic investigation of methylene blue concentrations, this work adds to the growing area of photoacoustic microscopy and highlights the value and adaptability of multi-wavelength imaging for molecular mapping. The findings could lead to improved molecular imaging and have consequences for researchers and practitioners in the fields of biomedical optics, spectroscopy, and photoacoustic imaging.
Photoacoustic imaging (PAI) is now a very promising medical imaging technology that provides structural, functional, and molecular information based on the optical absorption of endogenous or exogenous contrast agents. A conventional PAI system using an array of ultrasonic transducers to detect photoacoustic (PA) signals. Each element of the transducer requires an amplifier to enhance the detected signal which makes it bulky. To overcome this problem, we introduced optical sensor alternative to piezoelectric ultrasound detector in PA signal detection. This study aims to illustrate the entire process of PA signal generation and its detection using an optical sensor using Finite Element software (COMSOL). Fiber Bragg grating (FBG) is one of the optical sensors that may be utilized in some applications in place of acoustic ones. FBG provides the change in acoustic pressure as a function of the shift of Bragg wavelength. Our study demonstrated that FBG achieves to detect photoacoustic (PA) signals as an alternative of US transducer, with superior performance in terms of sensitivity, and being more light-weight, flexible, and cost-effective. This implies that these technologically novel qualities hold promise for the use of FBG (either single or multiple units on a single fiber) as an acoustic sensor in PAI systems in place of the conventional piezoelectric-based bulk array transducer. An intensity-based demodulation was performed to extract the US signal. The preliminary study demonstrates that the integration of FBG in PA imaging modality offers potential as a future (imaging) technology both for biological studies and clinical applications.
Photoacoustic imaging (PAI) is now a very promising imaging technique that provides image with sufficient depth, good resolution, and optical contrast. A conventional PAI system is relatively expensive and mechanically bulky. The study demonstrated that MEMS PMUT achieves miniaturized ultrasound (US) sensor element (either single element or an array of elements) with superior performance in terms of power consumption, flexibility, broader bandwidth, and sensitivity. This implies that these technologically novel qualities hold promise for the use of PMUT as an acoustic sensor in PAI systems in place of the conventional piezoelectric bulk element-based spherical ultrasound (US) transducer. We report our study on the design and development of MEMS PMUT−(central frequency ~ 1MHz) based PAM−that integrates MEMS technology and imaging technology (specifically, photoacoustic imaging (PAI)). In this work, we present a temporal integration of the signals over a certain number (~20) of pulsed light-induced PA waves against the conventional technique to acquire a single 1D PA signals/data corresponding to one individual optical pulse−induced PA waves. This means to say that the enhancement of imaging performance with the use of PMUT acoustic sensor is associated with a reduction of obtainable temporal resolution, i.e., a trade-off exists. With the applied temporal integration method SNR has been improved ~ 20dB. The preliminary study demonstrates that the integration of PMUT in PA imaging modality holds promise as a future (imaging) technology both for biological studies and their applications.
The eyes function through the cooperation of different ocular components, and complications with any components would lead to ocular diseases that deteriorate vision. Hence early and precise detection and monitoring of ocular diseases, along with the improved understanding of pathological mechanisms, becomes essential for successful treatment. Photoacoustic Imaging (PAI) is a non-invasive and non-destructive imaging modality based on the photoacoustic effect, which gives high spatial resolution, sensitivity, contrast and penetration depth. Since PAI can provide anatomic and functional ocular characterizations, it can be a potential tool for medical screening/diagnosis of ocular diseases, staging, treatment, and continuous post-treatment monitoring. Here, we perform deep-tissue imaging of the Goldfish (Carassius auratus) eye using a home-built Photoacoustic microscope to identify various ocular components like iris, crystalline lens, retina, optic nerve and blood vessels. The study can be extended to observe changes in these structures under different ophthalmic disease conditions.
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