||Peter A. Lewin, Ph.D.
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Richard B. Beard Professor, School of Biomedical Engineering, Science & Health Systems
Richard B. Beard Professor, Electrical & Computer Engineering
Office: Bossone 7-701 Email: email@example.com
Phone: 215.895.2361 Fax: 215.895.4983
Laboratory Web Page: Click Here to Visit Laboratory Web Page
Ultrasonic characterization of materials, propagation of ultrasonic waves in inhomogeneous media, electro-acoustic transducers, biological effects of ultrasound, physical acoustics, and underwater acoustics.
Dr. Peter Lewin, Richard B. Beard Professor of Electrical and Computer Engineering and Biomedical Engineering, is a recipient of the Drexel University Distinguished Professor Award. Dr. Lewin is also appointed as the director of the Ultrasound Research and Education Center in the School of Biomedical Engineering, Science, and Health Systems. Recently, he was also appointed to the prestigious Franklin Institute Committee on Science and the Arts.
Ph.D., University of Denmark, Copenhagen-Lyngby, Denmark, Physical Acoustics, 1979
M.S., University of Denmark, Copenhagen-Lyngby, Denmark, Electrical Engineering, 1969
Active Research Projects:
1. Very High Frequency Ultrasonic Exposimetry: The purpose of this project is to develop acousto-optic measurement method capable of determining absolute sensitivity of miniature ultrasonic hydrophone probes over a wide 100 MHz bandwidth. There is a well defined need for such work: Firstly, clinical impact of ultrasound is steadily rising and ultrasound is emerging as one of the most important imaging modalities. Secondly, although a majority of presently used ultrasonic imaging systems operates at frequencies not exceeding 15 MHz, the current research concentrates on diagnostic applications of ultrasound at frequencies well beyond 20 MHz in order to achieve sub-millimeter resolution. Thirdly, the hydrophone probes are typically calibrated up to 20 MHz and their behavior beyond 20 MHz is (usually) not known. Our preliminary data, predicted using nonlinear wave propagation model and verified experimentally, indicate that the approach developed will allow sensitivity of the hydrophone probes to be determined up to 100 MHz.
2. Spatial Averaging for Circular and Rectangular Shapes Sources: Very high frequency (beyond 20 MHz) characterization of the acoustic fields involves often measurements produced by the sources with low focal numbers. Such sources are very tightly focused and can have cross-section of the beam on the order of tens (e.g.50) of microns. However, the hydrophone probes used to measure those fields have active elements approximately an order of magnitude higher which leads to spatial averaging errors. We are developing a nonlinear propagation model able to predict the correction needed for differently shaped - circular and rectangular - sources and accounting for frequency dependent effective area of the hydrophone, source and focal distance.
3. Characterization of acoustic transducers below 1 MHz: The aim of this project is to develop and verify an absolute calibration method which can rapidly determine sensitivity of ultrasonic hydrophone probes below 1 MHz. Such calibration is required for hydrophones used in measurements of acoustic output of ultrasound devices. Acoustic output information has to be supplied by the manufacturer to the Food and Drug Administration (FDA) in order to obtain clearance for clinical applications. Ultrasound imaging devices produce ultrasound fields which contain frequency components well below 1 MHz due to nonlinear propagation phenomena. Also, High Intensity Focused Ultrasound (HIFU) devices operate in the frequency range 450-750 kHz. These devices are clinically tested as possible tools, e.g. for abatement of cancerous prostate cells. Moreover, below 1 MHz frequency components are present in lithotripters, machines which use focused acoustic energy for non-surgical removal of kidney stones. Outside-the-body pulverization of the stone allows fragments to pass in the natural way. We are developing a unique calibration method that will provide sensitivity of the hydrophone probes as a continuous function of frequency from 250 kHz - 1 MHz and can be extended to even lower frequencies.
4. Ultrasound and Wound Healing: This project examines beneficial interaction of ultrasound energy with biological tissue and aims at determining the exposure matrix which would optimize acceleration of wound healing. Of particular interest are chronic ulcers such as diabetic foot ulcers and bed sores. The exposure matrix includes such field parameters as frequency, pulse duration and pulse repetition frequency, and spatial peak-temporal average intensity. Preliminary experiments carried out using cell cultures in vitro indicated that appropriately adjusted exposure matrix stimulated the cells to produce collagen. Collagen is indispensable as a component needed for tissue healing. The results of this research will provide insights into the interaction between ultrasound and biological tissue and may help develop more effective ways of wound management.
5. Acoustic Sensors (with Dr. Lec): This research focuses on development of biosensors based on acoustic wave transduction for applications in healthcare industry. Attention is focused on development of miniature acoustic biosensors for applications in medicine and clinical diagnostics such as accelerated analysis of blood and identification of the nature of biochemical (immuno-) reactions. All sensors employ a versatile piezoelectric platform and are designed to take advantage of hybrid, analog-digital, and wireless technology, which will facilitate their full miniaturization and portability. The hybrid technology was chosen because it will allow monitoring of biological response to chemical stimulants on-line and will facilitate dynamic digital information storage for immediate transfer and documentation.
P.A. Lewin, C. Mu, S. Umchid, A. Daryoush and M. A. El-Sherif, Acousto-optic, point receivier hydrophone probe for operation up to 100 MHz, Ultrasonics, 43(10), 815-821, 2005.
PA.Lewin, S.Umchid, A. Sutin and A. Sarvazyan, Beyond 40 MHz frontier:
The future technologies for calibration and sensing of acoustic
fields. Journal of Physics CS, (1) 2004, pp.38-43.
PA. Lewin and JR Reid Piezoelectric Devices in Biomedical Applications,
J. Wiley Biomedical Engineering Encyclopedia, accepted for publication.
E.Radulescu, P.A. Lewin, and A. Nowicki, 1-60 MHz Measurements in Focused Acoustic Fields using Spatial Averaging Corrections. Ultrasonics, v. 40, Pages 497-501, 2002.
E.G. Radulescu, P.A.Lewin, A.Nowicki and P.M. Shankar, Performance
evaluation of wideband ultrasound hydrophone probes. Proceedings of the
IEEE 28th Annual Northeast Bioengineering Conference, Philadelphia, PA,
pp.249-250, April 2002, (paper awarded 2nd prize).
E.G. Radulescu, P.A. Lewin, A. Goldstein and A. Nowicki, Hydrophone spatial averaging corrections from 1-40 MHz, IEEE Trans. UFFC, 48 (6) Nov. 2001, pp. 1575-1580.
H. Bleeker and P. A. Lewin, A novel method for determining calibration and behavior of PVDF ultrasonic hydrophone probes in the frequency range up to 100 MHz, IEEE Transactions UFFC 47(6), 1354-1362, 2000.
A. Selfridge and P.A. Lewin, Wideband Spherically Focused PVDF Acoustic Sources for Calibration of Ultrasound Hydrophone Probes, IEEE Transactions UFFC 47(6), 1372-1376, 2000.
G.R. Harris and P.A. Lewin, Acoustic Exposimetry, chapter in Encyclopedia of Electrical and Electronics Engineering, J. Wiley, v.22, pp 634-646, 1999.
J.M. Reid and P.A. Lewin, Ultrasound Imaging Transducers, chapter in Encyclopedia of Electrical and Electronics Engineering, J. Wiley, v.22, pp 664-672, 1999.
B. Haider, P. A. Lewin, K.E. Thomenius, Pulse elongation and deconvolution filtering for medical ultrasonic imaging, IEEE Trans. UFFC, v.48 (1), 98-113 (1998).
Q. Zhang, P.A. Lewin, and P.E. Bloomfield, PVDF transducer - A Performance Comparison of a Single Layer and Multilayer Structures, IEEE Trans. UFFC, 44, 1148-1156 (1997).
P.A. Lewin, R. Bhatia, Q. Zhang, Characterization of Optoacoustic Surgical Devices, IEEE Trans. UFFC, 43 (4) pp 519-526 (1996).
"Intravascular, Ultrasonic Imaging Catheters and Methods for Making Same." U.S. Patent #5,109,861.
"Miniature Ultrasonic Catheters, and Methods for Making Same," U.S. Patent #5,240,004.
Peter A. Lewin, M.Sc., Ph.D. is R.B. Beard Professor of Electrical and Computer Engineering and Biomedical Engineering at Drexel University, Philadelphia. He is also Director of the Ultrasound Research and Education Center in The School of Bioengineering, Bioscience and Health Systems at Drexel University. Dr. Lewin obtained his M.S. degree in Electrical Engineering in 1968 and the Ph.D. in Physical Acoustics in 1979 in Copenhagen, Denmark. Before receiving his Ph.D. degree he was employed by Bruel and Kjaer, Denmark, where he was involved in the development of underwater piezoelectric transducers and associated electronics. From 1978 to 1983 he was associated with the Danish Institute of Biomedical Engineering (now Force Institutes) and The University of Denmark, Copenhagen, where his research activities primarily focused on propagation of ultrasound waves in inhomogeneous media and development of PVDF polymer transducers. In 1983 he joined the faculty of Drexel University. Dr. Lewin was awarded several patents in the field of ultrasound and has authored or co-authored over 200 scientific publications, most of them on topics in ultrasound and is co-editor (with Prof. M. C. Ziskin) of a book Ultrasonic Exposimetry (CRC Press, 1993). His current interests are primarily in the field of biomedical ultrasonics including the design and testing of piezoelectric transducers and sensors, power ultrasonics, ultrasonic exposimetry, tissue characterization using nonlinear acoustics, biological effects of ultrasound, applications of shock waves in medicine and image reconstruction and processing. Dr. Lewin is a Fellow of the Institute of Electrical and Electronics Engineers (IEEE) and a Fellow of the Acoustical Society of America. He is also a Fellow of the American Institute of Ultrasound in Medicine (AIUM and served as a Chair (1997-1999) of the AIUM's Technical Standards Committee. In addition, Dr. Lewin is a member of the honorary Society Sigma Xi and serves as a consultant to the U.S. Food and Drug Administration, Center for Devices and Radiological Health. Dr. Lewin is also a chairman of one of the working groups within the International Electrotechnical Commission (IEC), Technical Committee on Ultrasonics. In 2007 he was elected Fellow of the American Institute for Medical and Biological Engineering.