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By J.-C. Chiao and Mohammad-Reza Tofighi

The recent IEEE International Microwave Symposium IMS 2013, held on June 2-7 in Seattle, WA, USA, presented up-to-date advanced radio frequency (RF) and microwave technologies for biomedical applications by world experts. In this article, we review the highlights of the sessions and workshops that were devoted to biological and medical applications.

Presentations in four podium sessions, one poster session, and two workshops highlighted the fast growing research of utilizing electromagnetic fields in biological exploration and medical applications. The presentations attracted many scientists and engineers, some have not been working in the medicine-related applications, and inspired many lively interactive discussions in the sessions and workshops.

The podium sessions focused on four diverse areas of applications:

(1) Recent developments in medical imaging, including magnetic resonance imaging (MRI) and microwave imaging methods. Papers reported recent developments in RF coils for ultra-high-field MRI systems such as automatic frequency tuning and impedance matching technique for the optimal coil efficiency at 7T and creating homogeneous magnetic field distributions. Techniques to improve range resolution for forward-scattered signals in a microwave imaging system were reported.

(2) Advanced concepts in biomedical radars and radar based techniques to address noninvasive vital signs monitoring. This session presented recent development in noise and body motion artifact cancellation approaches for vital sign sensing with radars, and an ultra-wideband micro-Doppler radar for human gait analysis that can track more than one person and detect vital sign of moving objects. One presentation discussed the use of a handheld communication device such as a cellular phone with antenna mismatching effects for vital sign detection.

(3) Microwave spectroscopy and sensing techniques for studying biological cells. Presentations focused on utilizing broadband signals to probe directly aqueous solution or a finite number of cells in integrated microfluidic devices. Results were discussed for determination of sugar concentration in solutions using ultra-wideband impedance spectroscopy and a 1 – 50 GHz dielectric spectroscopy biosensor with an integrated 65-nm CMOS receiver front-end. Four papers focused on human normal and cancerous cell studies including detection of live and dead human cells in a broadband microchamber; micro-dosimetric studies for single cells with nanosecond pulsed electric fields; a tunable frequency resonant sensor for cell cytoplasm analysis based on dielectric permittivity variations; a dielectric spectroscopic sensor to probe a single alive cell in an integrated microfluidic platform from 40MHz to 40GHz; and electroporation and dielectrophoresis of single cells in a microfluidic system employed with a microwave interferometric sensor.

(4) Medical implantable devices and handheld systems utilizing RF and microwave for telemetry and powering. A wireless sensor with dual on-chip antennas operated at 5.2 GHz and RF powered at 0.5 mW for implantable intraocular pressure monitoring; a study to determine specific absorption rates of textile antennas for on-body medical telemetry applications at 2.4 GHz and 5.2 GHz; a multiband 2-Port vector network analyzer at 6.6 GHz, 19.7 GHz, and 32.4 GHz with an embedded coplanar permittivity sensor for measurements in aqueous solutions; and a single-chip dual-mode continuous-wave and pulsed electron paramagnetic resonance spectrometer based on 0.13 µm SiGe BiCMOS were reported.

Two workshops brought focused discussion from international experts on electro-nanoporation effects on biological systems, and microwave sensors/biochips for biomolecules and cells characterization.

The Monday workshop organized by Professors Guglielmo d’Inzeo at La Sapienza University of Rome and James Hwang at Lehigh University presented four related topics in the emerging and intriguing field of research utilizing short (from nanoseconds to microseconds) and intense (amplitudes in the megavolt-per-meter range) pulsed electric fields (ms/ns PEFs) on human cells to explore new scientific studies and practical applications in medicine. Promising results were reported for gene transfer techniques to enhance delivery to cell nucleus and induce cancer treatment with complete melanoma remission, and for neuromuscular, neurophysiological, and cardiac stimulation. The workshop covered state-of-the-art research on nsPEFs, including generator design and assembly, electrode layout, micro-chamber development, modeling and simulation, and recent medical applications.

The Friday workshop organized by Drs. Katia Grenier at LAAS-CNRS and Arnaud Pothier at XLIM-CNRS addressed the latest advances on the microwave-, millimeter-, submillimeter-wave, and THz probing instrumentations suitable for in-situ investigation of biomolecules, single cell, cells suspensions, and tissues in microfluidic systems. Accurate/noninvasive biological samples characterizations and analysis as well as the instrumentation designs and features were highlighted by ten international researchers. Presentations highlighted resonant and broadband approaches for respective targeted applications such as precise cell identification, diagnostic and prognostic applications for cancers, point-of-care diagnosis tools, and handheld devices for biomolecule characterization. Examples showed the potentials of high frequency dielectric spectroscopy for cell analysis by extracting intracellular dielectric properties up to single cell. Such measurements can be utilized to sort out alive or dead cells, cell types, cancer cell aggressiveness, and cell immaturity. Precise measurements of subtle changes of the relaxation of water, which is induced by dissolved/dispersed proteins or cells, were conducted at the microwave to terahertz frequency ranges with broadband and high-Q resonator methods. The results underlined the potentials for free-solution and label free biosensor applications. Cancer tissue that has a higher water content than healthy tissue produced a significantly different microwave signature. Near-field millimeter-wave measurements utilizing a high-resolution micromachined probe was applied for skin cancer diagnosis based on the electromagnetic signatures. Instrumentation, tissue and skin modeling, characterization data, and calibration procedures were presented.

Applications of electromagnetic waves demonstrated in device and system implementation for telemetry and powering of medical implants, studies and identification of biological cells and molecules in aqueous solutions, new modalities of medical imaging techniques, and remote monitoring and sensing of vital signs brought great attention and interests to microwave and RF engineers and researchers in industries and academia. In IMS2013, the inspiring presentations and sparkling discussions indicated numerous challenges to overcome and enormous opportunity in the near future for healthcare applications.

For Further Reading

The session and workshop information can be found at http://www.mtt-archives.org/~mtt10/Events.htm.
The workshop agendas are listed at http://www.ims2013.org/technical-program/workshops.
The sessions information can be found at http://program.ims2013.org/users/sched or in the IMS 2013 program book: http://www.ims2013.org/technical-program/program-book.

Contributors

J.-C. Chiao is Greene endowed professor and Garrett endowed professor of Electrical Engineering at University of Texas – Arlington; and an Adjunct Associate Professor in the Internal Medicine Department at UT-Southwestern, Medical Center. Read more

Mohammad-Reza Tofighi is an associate professor of electrical engineering with the Capital College, Pennsylvania State University, Middletown, PA. He conducts research on wireless implants, biomedical antennas, medical applications of microwave radiometry, and complex permittivity measurement of tissues using time and frequency domain methods. Read more