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4 April 2017 Low-power noncontact photoacoustic microscope for bioimaging applications
Krishnan Sathiyamoorthy, Eric M. Strohm, Michael C. Kolios
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Journal of Biomedical Optics, Vol. 22, Issue 4, 046001 (April 2017). https://doi.org/10.1117/1.JBO.22.4.046001
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 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  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.
CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
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Krishnan Sathiyamoorthy, Eric M. Strohm, and Michael C. Kolios "Low-power noncontact photoacoustic microscope for bioimaging applications," Journal of Biomedical Optics 22(4), 046001 (4 April 2017). https://doi.org/10.1117/1.JBO.22.4.046001
Received: 26 May 2016; Accepted: 7 March 2017; Published: 4 April 2017
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Cited by 16 scholarly publications.
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KEYWORDS
Imaging systems
Photoacoustic spectroscopy
Sensors
Blood
Microscopes
Spectroscopy
Modulation transfer functions
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