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Das D, Sharma A, Rajendran P, Pramanik M. Another decade of photoacoustic imaging. Phys Med Biol 2020; 66. [PMID: 33361580 DOI: 10.1088/1361-6560/abd669] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 12/23/2020] [Indexed: 01/09/2023]
Abstract
Photoacoustic imaging - a hybrid biomedical imaging modality finding its way to clinical practices. Although the photoacoustic phenomenon was known more than a century back, only in the last two decades it has been widely researched and used for biomedical imaging applications. In this review we focus on the development and progress of the technology in the last decade (2010-2020). From becoming more and more user friendly, cheaper in cost, portable in size, photoacoustic imaging promises a wide range of applications, if translated to clinic. The growth of photoacoustic community is steady, and with several new directions researchers are exploring, it is inevitable that photoacoustic imaging will one day establish itself as a regular imaging system in the clinical practices.
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Affiliation(s)
- Dhiman Das
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, SINGAPORE
| | - Arunima Sharma
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, SINGAPORE
| | - Praveenbalaji Rajendran
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore, SINGAPORE
| | - Manojit Pramanik
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 70 Nanyang Drive, N1.3-B2-11, Singapore, 637457, SINGAPORE
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Wang H, Ma Y, Yang H, Jiang H, Ding Y, Xie H. MEMS Ultrasound Transducers for Endoscopic Photoacoustic Imaging Applications. MICROMACHINES 2020; 11:E928. [PMID: 33053796 PMCID: PMC7601211 DOI: 10.3390/mi11100928] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/03/2020] [Accepted: 10/04/2020] [Indexed: 12/14/2022]
Abstract
Photoacoustic imaging (PAI) is drawing extensive attention and gaining rapid development as an emerging biomedical imaging technology because of its high spatial resolution, large imaging depth, and rich optical contrast. PAI has great potential applications in endoscopy, but the progress of endoscopic PAI was hindered by the challenges of manufacturing and assembling miniature imaging components. Over the last decade, microelectromechanical systems (MEMS) technology has greatly facilitated the development of photoacoustic endoscopes and extended the realm of applicability of the PAI. As the key component of photoacoustic endoscopes, micromachined ultrasound transducers (MUTs), including piezoelectric MUTs (pMUTs) and capacitive MUTs (cMUTs), have been developed and explored for endoscopic PAI applications. In this article, the recent progress of pMUTs (thickness extension mode and flexural vibration mode) and cMUTs are reviewed and discussed with their applications in endoscopic PAI. Current PAI endoscopes based on pMUTs and cMUTs are also introduced and compared. Finally, the remaining challenges and future directions of MEMS ultrasound transducers for endoscopic PAI applications are given.
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Affiliation(s)
- Haoran Wang
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA;
| | - Yifei Ma
- School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China; (Y.M.); (Y.D.)
| | - Hao Yang
- Department of Medical Engineering, University of South Florida, Tampa, FL 33620, USA; (H.Y.); (H.J.)
| | - Huabei Jiang
- Department of Medical Engineering, University of South Florida, Tampa, FL 33620, USA; (H.Y.); (H.J.)
| | - Yingtao Ding
- School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China; (Y.M.); (Y.D.)
| | - Huikai Xie
- School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China; (Y.M.); (Y.D.)
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Chalklen T, Jing Q, Kar-Narayan S. Biosensors Based on Mechanical and Electrical Detection Techniques. SENSORS (BASEL, SWITZERLAND) 2020; 20:E5605. [PMID: 33007906 PMCID: PMC7584018 DOI: 10.3390/s20195605] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/18/2020] [Accepted: 09/23/2020] [Indexed: 12/20/2022]
Abstract
Biosensors are powerful analytical tools for biology and biomedicine, with applications ranging from drug discovery to medical diagnostics, food safety, and agricultural and environmental monitoring. Typically, biological recognition receptors, such as enzymes, antibodies, and nucleic acids, are immobilized on a surface, and used to interact with one or more specific analytes to produce a physical or chemical change, which can be captured and converted to an optical or electrical signal by a transducer. However, many existing biosensing methods rely on chemical, electrochemical and optical methods of identification and detection of specific targets, and are often: complex, expensive, time consuming, suffer from a lack of portability, or may require centralised testing by qualified personnel. Given the general dependence of most optical and electrochemical techniques on labelling molecules, this review will instead focus on mechanical and electrical detection techniques that can provide information on a broad range of species without the requirement of labelling. These techniques are often able to provide data in real time, with good temporal sensitivity. This review will cover the advances in the development of mechanical and electrical biosensors, highlighting the challenges and opportunities therein.
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Affiliation(s)
| | - Qingshen Jing
- Department of Materials Science, University of Cambridge, Cambridge CB3 0FS, UK;
| | - Sohini Kar-Narayan
- Department of Materials Science, University of Cambridge, Cambridge CB3 0FS, UK;
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Dangi A, Agrawal S, Datta GR, Srinivasan V, Kothapalli SR. Towards a Low-Cost and Portable Photoacoustic Microscope for Point-of-Care and Wearable Applications. IEEE SENSORS JOURNAL 2020; 20:6881-6888. [PMID: 32601522 PMCID: PMC7323929 DOI: 10.1109/jsen.2019.2935684] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Several breakthrough applications in biomedical imaging have been reported in the recent years using advanced photoacoustic microscopy imaging systems. While two photon and other optical microscopy systems have recently emerged in portable and wearable form, there is much less work reported on the portable and wearable photoacoustic microscopy (PAM) systems. Working towards this goal, we report our studies on a low-cost and portable photoacoustic microscopy system that uses a custom fabricated 2.5 mm diameter ring ultrasound transducer integrated with a fiber-coupled laser diode. The ultrasound transducer is centered at 17.25 MHz, and shows ~ 45% and ~ 100% fractional bandwidths for ultrasound pulse-echo and photoacoustic A-line signals respectively. To achieve overall system portability, besides the imaging head, other backend imaging system components need to be readily portable as well. In this direction, we have studied the potential use of compact pre-amplifiers, scanning stages and microcontroller based data acquisition and reconstruction for photoacoustic imaging. The portable PAM system is validated by imaging phantoms embedded with light absorbing targets. Future directions that will likely help achieve a completely portable and wearable photoacoustic microscopy system are discussed.
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Affiliation(s)
- Ajay Dangi
- Department of Biomedical Engineering, Pennsylvania State University, University Park, USA
| | - Sumit Agrawal
- Department of Biomedical Engineering, Pennsylvania State University, University Park, USA
| | - Gaurav Ramesh Datta
- School of Electrical Engineering and Computer Science, Pennsylvania State University, University Park, USA
| | - Visweshwar Srinivasan
- School of Electrical Engineering and Computer Science, Pennsylvania State University, University Park, USA
| | - Sri-Rajasekhar Kothapalli
- Department of Biomedical Engineering, Pennsylvania State University, University Park, USA and Penn State Cancer Institute, Pennsylvania State University, Hershey, Pennsylvania, USA
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Agrawal S, Fadden C, Dangi A, Yang X, Albahrani H, Frings N, Heidari Zadi S, Kothapalli SR. Light-Emitting-Diode-Based Multispectral Photoacoustic Computed Tomography System. SENSORS 2019; 19:s19224861. [PMID: 31717260 PMCID: PMC6891584 DOI: 10.3390/s19224861] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 11/02/2019] [Accepted: 11/06/2019] [Indexed: 12/16/2022]
Abstract
Photoacoustic computed tomography (PACT) has been widely explored for non-ionizing functional and molecular imaging of humans and small animals. In order for light to penetrate deep inside tissue, a bulky and high-cost tunable laser is typically used. Light-emitting diodes (LEDs) have recently emerged as cost-effective and portable alternative illumination sources for photoacoustic imaging. In this study, we have developed a portable, low-cost, five-dimensional (x, y, z, t, λ ) PACT system using multi-wavelength LED excitation to enable similar functional and molecular imaging capabilities as standard tunable lasers. Four LED arrays and a linear ultrasound transducer detector array are housed in a hollow cylindrical geometry that rotates 360 degrees to allow multiple projections through the subject of interest placed inside the cylinder. The structural, functional, and molecular imaging capabilities of the LED-PACT system are validated using various tissue-mimicking phantom studies. The axial, lateral, and elevational resolutions of the system at 2.3 cm depth are estimated as 0.12 mm, 0.3 mm, and 2.1 mm, respectively. Spectrally unmixed photoacoustic contrasts from tubes filled with oxy- and deoxy-hemoglobin, indocyanine green, methylene blue, and melanin molecules demonstrate the multispectral molecular imaging capabilities of the system. Human-finger-mimicking phantoms made of a bone and blood tubes show structural and functional oxygen saturation imaging capabilities. Together, these results demonstrate the potential of the proposed LED-based, low-cost, portable PACT system for pre-clinical and clinical applications.
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Affiliation(s)
- Sumit Agrawal
- Department of Biomedical Engineering, Pennsylvania State University, University Park, State College, PA 16802, USA; (S.A.); (A.D.); (X.Y.); (H.A.); (N.F.); (S.H.Z.)
| | - Christopher Fadden
- Department of Electrical Engineering, Pennsylvania State University, University Park, State College, PA 16802, USA;
| | - Ajay Dangi
- Department of Biomedical Engineering, Pennsylvania State University, University Park, State College, PA 16802, USA; (S.A.); (A.D.); (X.Y.); (H.A.); (N.F.); (S.H.Z.)
| | - Xinyi Yang
- Department of Biomedical Engineering, Pennsylvania State University, University Park, State College, PA 16802, USA; (S.A.); (A.D.); (X.Y.); (H.A.); (N.F.); (S.H.Z.)
| | - Hussain Albahrani
- Department of Biomedical Engineering, Pennsylvania State University, University Park, State College, PA 16802, USA; (S.A.); (A.D.); (X.Y.); (H.A.); (N.F.); (S.H.Z.)
| | - Neilesh Frings
- Department of Biomedical Engineering, Pennsylvania State University, University Park, State College, PA 16802, USA; (S.A.); (A.D.); (X.Y.); (H.A.); (N.F.); (S.H.Z.)
| | - Sara Heidari Zadi
- Department of Biomedical Engineering, Pennsylvania State University, University Park, State College, PA 16802, USA; (S.A.); (A.D.); (X.Y.); (H.A.); (N.F.); (S.H.Z.)
| | - Sri-Rajasekhar Kothapalli
- Department of Biomedical Engineering, Pennsylvania State University, University Park, State College, PA 16802, USA; (S.A.); (A.D.); (X.Y.); (H.A.); (N.F.); (S.H.Z.)
- Penn State Cancer Institute, Pennsylvania State University, Hershey, PA 17033, USA
- Graduate Program in Acoustics, The Pennsylvania State University, University Park, PA 16802, USA
- Correspondence:
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Chan J, Zheng Z, Bell K, Le M, Reza PH, Yeow JTW. Photoacoustic Imaging with Capacitive Micromachined Ultrasound Transducers: Principles and Developments. SENSORS (BASEL, SWITZERLAND) 2019; 19:E3617. [PMID: 31434241 PMCID: PMC6720758 DOI: 10.3390/s19163617] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/15/2019] [Accepted: 08/18/2019] [Indexed: 12/14/2022]
Abstract
Photoacoustic imaging (PAI) is an emerging imaging technique that bridges the gap between pure optical and acoustic techniques to provide images with optical contrast at the acoustic penetration depth. The two key components that have allowed PAI to attain high-resolution images at deeper penetration depths are the photoacoustic signal generator, which is typically implemented as a pulsed laser and the detector to receive the generated acoustic signals. Many types of acoustic sensors have been explored as a detector for the PAI including Fabry-Perot interferometers (FPIs), micro ring resonators (MRRs), piezoelectric transducers, and capacitive micromachined ultrasound transducers (CMUTs). The fabrication technique of CMUTs has given it an edge over the other detectors. First, CMUTs can be easily fabricated into given shapes and sizes to fit the design specifications. Moreover, they can be made into an array to increase the imaging speed and reduce motion artifacts. With a fabrication technique that is similar to complementary metal-oxide-semiconductor (CMOS), CMUTs can be integrated with electronics to reduce the parasitic capacitance and improve the signal to noise ratio. The numerous benefits of CMUTs have enticed researchers to develop it for various PAI purposes such as photoacoustic computed tomography (PACT) and photoacoustic endoscopy applications. For PACT applications, the main areas of research are in designing two-dimensional array, transparent, and multi-frequency CMUTs. Moving from the table top approach to endoscopes, some of the different configurations that are being investigated are phased and ring arrays. In this paper, an overview of the development of CMUTs for PAI is presented.
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Affiliation(s)
- Jasmine Chan
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Zhou Zheng
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Kevan Bell
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Martin Le
- Department of Physics, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Parsin Haji Reza
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
| | - John T W Yeow
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
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