Ultrasound News: Sound Idea
By Brett Adams
Radiology Today
Vol. 20 No. 1 P. 6

An ultracheap, ultraslim, ultraclear ultrasound is on the horizon.

Breast cancer, prostate cancer, liver diseases, and cardiac diseases—some of the most common causes of death in the United States—can all be detected using ultrasound and treated more effectively if they are detected in earlier stages. Unfortunately, due to the associated costs, many hospitals are unable to carry more than a few ultrasound machines. Because of limited availability, patients may be unable to obtain imaging in a timely manner, sometimes having to wait many weeks for a scheduled ultrasound. A technological breakthrough, however, may make ultrasound machines significantly less expensive to produce.

Today, most ultrasound transducers use piezoelectric crystals to receive voltage and generate ultrasound waves. Since 1991, there have been advances in this technology with the creation of tiny vibrating drums called capacitive micromachined ultrasonic transducers (CMUTs). But the manufacturing costs for piezoelectric crystals and CMUTs include expensive semiconductors, specialized equipment, an environmentally controlled laboratory, and hazardous gases and solvents. This is where engineers from the University of British Columbia (UBC) struck gold, or, more specifically, developed the path to a $100 ultrasound machine; the UBC engineers recently developed an inexpensive method of producing CMUTs.

A Jolt of Creativity
"Our technology uses tiny vibrating drums made out of polymers called polyCMUTs," says Carlos Gerardo, PhD, an engineer at UBC. "The diameter of each of these drums is around one-tenth of a millimeter [the same as the diameter of a human hair]. We have thousands of these drums in our transducer that vibrate at the same time and produce ultrasound waves." It is this breakthrough—the manufacturing of polyCMUTs uses fewer fabrication steps and a minimal amount of equipment—that makes all the difference in cost.

Using the much softer plasticlike material, as opposed to hard piezoelectric crystals, Gerardo and his team also found that, "if you use a softer material, you get better acoustic efficiency." However, they also realized that a much larger voltage needed to be applied to generate the ultrasound waves. In order to solve the high voltage issue, they spent hundreds of hours trying to find the right combination of polyCMUTs and energy.

Gerardo explains, "We solved this by altering the initial design and adding an extra fabrication step. This allowed us to obtain even a higher sensitivity at much lower voltages [<15 V]."

According to Gerardo, the first clinical applications appear headed for "cardiovascular ultrasound imaging or abdominal ultrasound … as they use linear arrays of transducers." Also, he suggests that "the future trend of ultrasound is to get conformal [flexible] ultrasound probes that can adapt to different curvature of the body." This new technology not only allows the transducer to be built into malleable material but also is smaller than a credit card.

If the engineers at UBC decide to create a standalone portable ultrasound machine, it will take a lot of time and effort to obtain FDA approval. But, as Gerardo points out, some ways around FDA approval include partnering with "existing ultrasound manufacturers to integrate our sensors in their products for a more tangible product at a short time.

"Another option is to use these devices in other applications outside biomedical that do not require FDA clearance," he says. "For instance, ultrasound is currently used to detect internal defects and cracks in the blades of plane turbines."

Smart Access
The new polyCMUT ultrasound transducers have game-changing potential; for as little as $100, Gerardo and his team foresee "the idea of creating an ultrasound system so cheap that even your family doctor or a general practitioner would be able to do a quick ultrasound scan for immediate diagnosis, instead of referring you to an ultrasound clinic or a hospital and waiting several weeks in some cases."

Gerardo imagines that, "with some training, your family doctor could immediately confirm the presence of breast cancer or a heart problem in the same room using a portable—and ultracheap—ultrasound scanner connected to a smartphone." This would provide people in remote locations with access to vital ultrasound technology.

The benefits of this technology go beyond its size, efficacy, and financial considerations. With decreased manufacturing costs, a hospital could afford to buy more ultrasound systems and lessen the waiting times for patients in need of an ultrasound scan. Small private practices and urgent care centers may also be able to get into the ultrasound game with much more confidence. Such efficiency would have the added effect of reducing patient anxiety and countless health problems that can stem from stress.

Gerardo has his eyes set on the future. "In the long run," he says, "we envision a wearable and small ultrasound system that can continuously monitor vital signs using ultrasound." Perhaps, one day, patients will be able to download an app and leverage the power of their smartphones to process the signals from this new transducer, in the comfort of their own homes.

— Brett Adams is a freelance writer based in Pittsburgh.