A Conversation with Physicist Y.C. Chen

A technological breakthrough in imaging that has applications in early diagnosis of eye ailments was the fruit of a recent collaboration between Professor Y.C. Chen, a laser specialist who is chairman of the Hunter Physics Department, and Dr. Ronald H. Silverman, then of the Weill Cornell Medical College Ophthalmology Department.

Silverman, a specialist in ultrasound imaging of the eye who is now at Columbia, was exploring the possibilities of combining ultrasound with light to improve image resolution; Chen wanted to apply his laser knowledge to the biomedical field. Together, the two invented a device that creates a detailed image of the eye, perhaps 20 times better than the images available with ultrasound alone - allowing doctors to see early signs of macular degeneration, tumors, oxygen shortages, and other danger signals.

The collaboration was a result of Hunter's partnership in the consortium of  institutions headed by Weill Cornell Medical College in the Clinical and Translational Science Center (CTSC). Established in 2008 with the aid of a $49 million grant from the National Institutes of Health, the center will translate research advances made in labs into new clinical methods used at the bedside. The men hope to have a  workable device in five years.

How does the photoacoustic imaging process work?

The way ultrasound works, you direct an ultrasound pulse at a tissue. It is reflected, and from the delay of the echo, you know where the reflection is taking place. A  computer processes the data and constructs the image. Ultrasound is well developed: it can penetrate where light cannot. But ultrasound has a limitation: the smallest thing you can see is about the size of a human hair. Doctors need to see much smaller things such as microvasculature and the optic nerve, and ultrasound cannot reveal enough details.

What we came up with uses a technique called photoacoustics. We generate  ultrasound by light: we direct a focused laser pulse toward the tissue. When the tissue absorbs the light, it warms up, expands and generates an ultrasound pulse. The laser beams can be focused better than the ultrasound. This way, we improved the resolution at least 20 times. With photoacoustic imaging, not only can you tell fine details, you can also tell what kind of tissue it is.

Could you say a few words about the collaboration?

The sciences in the 21st century will be driven by interdisciplinary research. The CTSC supports interdisciplinary and cross-institutional research. I have limited knowledge about the human body and ultrasound, while my collaborator needs my laser technology to help break the limitations of his technology. The collaboration not only solves the problem that brought us together, but also opens up many new ideas and opportunities.

What else could your technique be used for?

Dermatology. It's good for anything that is a few millimeters deep - or else for the eye, because it's transparent. We are also working to shrink the device so it may be used to examine places that can be reached by an endoscope.

What's next in your lab?

We are developing techniques that will let us focus the laser beam through a non-transparent medium. It is like seeing through ground glass. Among the people in my lab are two students who just graduated with their doctoral degrees, Fanting Kong and Liping Liu.

How did you come to Hunter?

I used to work in industry, but quite often, in industry, if something doesn't work in six months, then you will be asked to change direction. It is hard to do research if management has only six months of patience. So I came to academics, which allows me to set my own direction.

What do you like about Hunter?

Hunter is very supportive. We have a very good academic program and smart students. And we offer very personal attention to students. In physics, we pretty much know every student, and my students helped in this project. We have a very close bond, and it's very enjoyable to see students starting productive careers. Also, New York City, of course, can't be beat.

Is this technique patented, and do you have other patents?

We submitted an "invention disclosure" through Cornell. I have nine patents, mostly from industry - various mini-lasers, some already commercial products, because a large part of my work in the past involved shrinking lasers from a bulky benchtop model to a little millimeter-sized chip without compromising performance.

What is your favorite thing about teaching?

Teaching physics makes me understand physics better. You think about the problem more and from different angles, and you understand it much better.

What are your pastimes outside of work?

Hiking. I have hiked parts of the Appalachian Trail. Wherever I go - to a conference, for example - I find the nearest place to hike, maybe a mountain, out in nature. Also, I like photography.

What's your favorite electronic device, and what does that tell us about you?

I have a Sony e-reader. It's wonderful. I can read both English and Chinese on it. There are thousands of years of Chinese literature without copyright. And I have every book of Thomas Friedman's on my e-reader.

What would your students be surprised to learn about you?

I cook very well. I like Italian cooking more than Chinese cooking, especially seafood. Cooking is great, especially now that you can find any recipe online. But when you do it once or twice, then you have your own recipe. It's mixed, blending flavors.