3-D medical scanner: New handheld imaging device to aid doctors on the 'diagnostic front lines'

In the operating room, surgeons can see inside the human body in real time using advanced imaging techniques, but primary care physicians, the people who are on the front lines of diagnosing illnesses, haven't commonly had access to the same technology -- until now. Engineers from the University of Illinois at Urbana-Champaign (UIUC) have created a new imaging tool for primary care physicians: a handheld scanner that would enable them to image all the sites they commonly examine, and more, such as bacterial colonies in the middle ear in 3-D, or monitor the thickness and health of patients' retinas. The device relies on optical coherence tomography (OCT), a visualization technology that is similar to ultrasound imaging, but uses light instead of sound to produce the images.

The team will present their findings at the Optical Society's (OSA) Annual Meeting, Frontiers in Optics (FiO) 2012, taking place Oct. 14 -- 18 in Rochester, N.Y.

To monitor chronic conditions such as ear infections, primary care physicians currently rely on instruments that are essentially magnifying glasses, says UIUC physician and biomedical engineer Stephen Boppart, who will present the team's findings at FiO. The new handheld imaging device would give doctors a way to quantitatively monitor these conditions, and possibly make more efficient and accurate referrals to specialists.

The scanners include three basic components: a near-infrared light source and OCT system, a video camera to relay real-time images of surface features and scan locations, and a microelectromechanical (MEMS)-based scanner to direct the light. Near-infrared wavelengths of light penetrate deeper into human tissues than other wavelengths more readily absorbed by the body. By measuring the time it takes the light to bounce back from tissue microstructure, computer algorithms build a picture of the structure of tissue under examination.

Diabetic patients in particular may benefit from the device. About 40 to 45 percent of diabetics develop leaky blood vessels in their retinas -- a condition called retinopathy, which can lead to thickening of the retina, blurry vision, and eventually blindness. The handheld OCT device would allow doctors to monitor the health of the retina, potentially catching retinopathy in its early stages. In some cases, changes in the eye could help doctors diagnose diabetes, Boppart says.

Boppart and his team are hopeful that falling production costs combined with smaller, more compact designs will enable more physicians to take advantage of the scanners, and become a common point-of-care tool. Eventually, they would like to see the imagers at work in developing countries as well. He and an international team of collaborators recently received a $5 million National Institutes of Health Bioengineering Research Partnership grant to further refine the device.

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Acoustic cell-sorting chip may lead to cell phone-sized medical labs

A technique that uses acoustic waves to sort cells on a chip may create miniature medical analytic devices that could make Star Trek's tricorder seem a bit bulky in comparison, according to a team of researchers.

The device uses two beams of acoustic -- or sound -- waves to act as acoustic tweezers and sort a continuous flow of cells on a dime-sized chip, said Tony Jun Huang, associate professor of engineering science and mechanics, Penn State. By changing the frequency of the acoustic waves, researchers can easily alter the paths of the cells.

Huang said that since the device can sort cells into five or more channels, it will allow more cell types to be analyzed simultaneously, which paves the way for smaller, more efficient and less expensive analytic devices.

"Eventually, you could do analysis on a device about the size of a cell phone," said Huang. "It's very doable and we're making in-roads to that right now."

Biological, genetic and medical labs could use the device for various types of analysis, including blood and genetic testing, Huang said.

Most current cell-sorting devices allow the cells to be sorted into only two channels in one step, according to Huang. He said that another drawback of current cell-sorting devices is that cells must be encapsulated into droplets, which complicates further analysis.

"Today, cell sorting is done on bulky and very expensive devices," said Huang. "We want to minimize them so they are portable, inexpensive and can be powered by batteries."

Using sound waves for cell sorting is less likely to damage cells than current techniques, Huang added.

In addition to the inefficiency and the lack of controllability, current methods produce aerosols, gases that require extra safety precautions to handle.

The researchers, who released their findings in the current edition of Lab on a Chip, created the acoustic wave cell-sorting chip using a layer of silicone -- polydimethylsiloxane. According to Huang, two parallel transducers, which convert alternating current into acoustic waves, were placed at the sides of the chip. As the acoustic waves interfere with each other, they form pressure nodes on the chip. As cells cross the chip, they are channeled toward these pressure nodes.

The transducers are tunable, which allows researchers to adjust the frequencies and create pressure nodes on the chip.

The researchers first tested the device by sorting a stream of fluorescent polystyrene beads into three channels. Prior to turning on the transducer, the particles flowed across the chip unimpeded. Once the transducer produced the acoustic waves, the particles were separated into the channels.

Following this experiment, the researchers sorted human white blood cells that were affected by leukemia. The leukemia cells were first focused into the main channel and then separated into five channels.

The device is not limited to five channels, according to Huang.

"We can do more," Huang said. "We could do 10 channels if we want, we just used five because we thought it was impressive enough to show that the concept worked."

Huang worked with Xiaoyun Ding, graduate student, Sz-Chin Steven Lin, postdoctoral research scholar, Michael Ian Lapsley, graduate student, Xiang Guo, undergraduate student, Chung Yu Keith Chan, doctoral student, Sixing Li, doctoral student, all of the Department of Engineering Science and Mechanics at Penn State; Lin Wang, Ascent BioNano Technologies; and J. Philip McCoy, National Heart, Lung and Blood Institute, National Institutes of Health.

The National Institutes of Health Director's New Innovator Award, the National Science Foundation, Graduate Research Fellowship and the Penn State Center for Nanoscale Science supported this work.

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