Thermal diffusivity variations in nanoparticle administered phantom tissues – a photoacoustic investigation

Joseph, James; Sathiyamoorthy, Krishnan; Murukeshan, Vadakke Matham; Woh, Lye Sun

doi:10.1051/epjap/2012120060

Cited by 1 publication

(1 citation statement)

References 29 publications

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“…[39][40][41] Thomas et al 42 detected subsurface flaws in aluminum in the PA magnitude to a depth of approximately one diffusion length (∼180 to 800 μm) over a wide range of chopping frequencies. Other than spectral measurements, the PA technique can also be used in several other applications such as the measurement of thermal diffusivity, 43 detection of phase transitions, 44 and luminescence quantum efficiency. 45 The present aim is to use this PA spectroscopy principle for photoacoustic microscopy (PAM) imaging applications.…”

Section: Introductionmentioning

confidence: 99%

Low-power noncontact photoacoustic microscope for bioimaging applications

2017

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Abstract. 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 μm 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 noiseequivalent 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 μPa. 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.

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