Currently, other blood-scanning systems with cellular resolution do exist, but they are far less practical, relying on bulky equipment or potentially harmful fluorescent dyes that must be injected into the bloodstream.
"An important feature of the technique is its reliance on reflected light from the flowing cells to form their images, thus avoiding the use of fluorescent dyes that could be toxic," Golan says. "Since the blood cells are in constant motion, their appearance is distinctively different from the static tissue surrounding them." The team's technique also takes advantage of the one-way flow of cells to create a compact probe that can quickly image large numbers of cells while remaining stationary against the skin.
At first, the narrow field of view of the microscope made it difficult for the team to locate suitable capillary vessels to image. To solve this, the researchers added a green LED and camera to the system to provide a wider view in which the blood vessels appeared dark because hemoglobin absorbs green light. "Unfortunately, the green channel does not help in finding the depth of the blood vessel," notes Golan. "Adjusting the imaging depth of the probe for imaging a small capillary is still a challenge we will address in future research."
The researchers are also working on a second generation system with higher penetration depth.
The new system might expand the range of possible imaging sites beyond the inside lip, which was selected as a test site since it was rich in blood vessels, has no pigment to block light, and doesn't lose blood flow in trauma patients.
Additional steps include work to miniaturize the system for ease
|Contact: Angela Stark|
Optical Society of America