Logo: University of Southern California

BME Ultrasonic Transducer Lab Pushing the Acoustic Envelope

New design should be able to provide much better images. Also coming: an "acoustic tweezer."

March 13, 2009 —

Headed by BME Professor K. Kirk Shung and funded by a $5 million grant from the National Institutes of Health (NIH), the Ultrasonic Transducer Resource Center (UTRC) is the only lab of its kind in the country.

UTRC is working on developing a high frequency ultrasound imaging systems, using the high frequency (>30 MHz) ultrasonic transducers and arrays it is creating for eye, skin and small animal imaging.

Professor Kirk Shung is excited to be working with collaborators from the Health Science Campus. (photo by Newly Paul)

It also serves as a resource for investigators who have a need for such devices, and is working with companies on commercialization.

“Currently, more than 12 collaborative and service projects are going on in our lab. We are pushing the technical envelope and exploring new clinical applications for ultrasound,” said Shung.

Shung’s lab is developing single element transducers at frequencies from 20 to 120 MHz and is also working on making prototype high frequency linear arrays and a real-time imaging system which could be tailored for commercialization.

Commercial clinical scanners used today, all array based, are noninvasive, cheap and portable, but cannot penetrate bone and lung tissue, have a limited acoustic window, are dependent on the skills of the operator and provide poor quality images in obese patients, according to Shung.

UTRC has advanced instrumentation
High frequency commercial scanners, so-called "ultrasonic biomicroscopes," all use mechanical scanning of a single element transducer with fixed focus. This means that the spatial resolution is not uniform throughout the field of view and the frame rate is limited to less than 40 frames per sec.

Shung's team's devices have a higher frame rate, do not have mechanical moving parts, provide better image quality and are easier to use than current commercial products, as well as potentially able to image more kinds of tissue.

The high frequency transducers that Shung’s lab is developing give a better spatial resolution while imaging small objects than current clinical scanners. “This technology can also be used for intravascular imaging. One can insert a catheter mounted ultrasonic transducer in a blood vessel to image the artery wall structure,” said Shung.

With support from NIH, the lab has also developed an "acoustic tweezer" for separating microscopic particles. These tweezers are a cousin of the laser or optical tweezers developed in the early 1990s. They can be used to manipulate cells, measure cellular forces and monitor the motility of sperms and bacteria attached to surfaces.

"We started developing the acoustic tweezer two years ago and finally we are able to experimentally show that particles can be trapped in an ultrasonic beam. When the beam moves, the particle will also move around. This would be a great tool for manipulating small objects in the order of a few microns," said Shung.

The next step of the research is to trap even smaller particles and cells using sharp beams with increased frequency and smaller wavelengths. “We want to apply for an NIH grant and we are actively seeking collaborators for this phase of the project,” the scientist said.

The challenges at this point involve experimenting to reach higher frequencies. Shung’s team was able to use MEMS technology to develop a 100 MHz linear array and is now exploring new directions in array technology.

“We’re developing linear rays to reach higher frequencies where existing commercial technologies have not reached yet,” said Shung. The most important thing, he says, is that his team is working not just in areas of academic interest, but also with different companies, trying to advance existing technologies. “We have successfully translated our technology to a company in Boston. Our technology is part of the device the company is trying to commercialize,”  he added.

He is excited to be working in conjunction with the health sciences department.

“I think it’s going to be great because in order to advance our research we need to have clinical collaborators and in the past it was quite difficult for me to seek out collaborators in the medical school. A closer interaction between engineering and medical schools would offer more opportunities for faculty members on both campuses to work together on research,” said Shung.