November R&D Round UpNovember 12, 2010 By: Melanie Martella, Sensors
This month, we have a definite medical slant. This month's stories include a metamaterial that boosts the quality of ultrasonic images, using weak microwaves to measure vital signs without having to use pesky electrodes, and a fast test for breast cancer that uses radio frequency to distinguish healthy from diseased tissue.
Clearer Ultrasonic Images
Ultrasound is very, very good at what it does, but because ultrasound imaging can't resolve features that are smaller than the wavelength of the sound waves used, sonagram images have limited resolution. That may change, however, thanks to the work of UC Berkeley and Universidad Autonoma de Madrid researchers who have used a metamaterial to drastically improve the resolution of sonography. And when I say drastically, I mean by a factor of 50. The key to their breakthrough (detailed in Robert Sanders' UC Berkeley news article, "Novel metamaterial vastly improves quality of ultrasound imaging"), is the use of a metamaterial—in this case, tiny hollow copper tubes, bundled together and placed near the object being scanned—that capture evanescent sound waves which are then used to reconstruct sub-wavelength detail and thus achieve far clearer sonographic images. Eventually, the metamaterial may find its way to an ultrasound probe near you. I look forward to this, because whenever a pregnant friend points at a blob on her sonogram and declares "that's his arm!" I currently have to take it on faith.
A Noncontact Alternative to Electrodes
It's not that I don't see the value in electrodes, I do, but for patients who are being monitored but are still expected to move around, they present a problem. As Science Daily reports in its article, "Portable Microwave Sensors for Measuring Vital Signs", physicist Atsushi Mase of Kyushu University in Japan and his colleague Daisuke Nagae have developed a method of monitoring vital signs by using very weak microwaves. As the microwaves scatter off the body, body motions—such as the chest wall moving as the patient inhales or exhales or as the heart beats—induce a shift in the wave's phase. The reflected waves are detected by a very sensitive microwave sensor. Through the magic of signal processing, the researchers can then extract, in near real-time, exactly how the person's heart rate is changing. The article lists a number of potential applications, not all of which are medical in nature.
Fast Breast Cancer Scanning
Of all the types of cancer that afflict humanity, breast cancer seems to be the one that gets the most notice. Mammograms used to try to detect breast cancer in its earliest stages work fairly well for women older than 50, but for younger women they're far less successful because, not to put too fine a point on it, younger women have denser breast tissue, which means that the difference between the density of a tumor (benign or malignant) and the density of the surrounding tissue just isn't different enough. This doesn't even touch on the stress involved when a lump is found, and the woman has to wait to find out just how worried she needs to be. Professor Zhipeng Wu of the University of Manchester in the U.K. has invented a portable scanner that can rapidly show whether tumors are present in the breast. As noted in "Portable breast scanner allows cancer detection in the blink of an eye", other researchers have successfully used RF or microwaves to detect breast cancer—the method relies on the dielectric difference between healthy and diseased tissue, so doesn't have the same problems that mammography does—but it took a few minutes to produce the diagnostic images and the test had to be performed at a medical facility.
Professor Wu's system couples computer tomography with an RF scanner to create a portable system that produces an image as soon as the woman places her breast in the cup of the device. Because it's fast, portable, and easy to use, it could provide more rapid and effective screening to doctors' offices.
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