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Fluid Skin Imaging for Better Resolution
By: Katie Schaefer, Cosmetics & Toiletries magazine
Posted: April 6, 2011, from the April 2011 issue of Cosmetics & Toiletries.
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Drawing from the liquid lens technology used to auto-focus cell phone cameras, Rolland and her team created a probe lens to image the skin quickly with lateral resolution, as well as a custom microscope designed around the technology. “This lens can refocus within 30 ms with the possibility to go faster,” Rolland said.
The device consists of two major components, the scan lens and the microscope head, which hosts the liquid lens. The liquid lens* is comprised of a droplet of water and oil and electrodes. Electrical current is then incorporated so that each time voltage passes through the electrodes in the liquid lens, it refocuses to take another image—i.e., electrowetting. Rolland explained, “As you apply voltage, the electrode becomes less hydrophobic and the junction of the oil/water interface changes shape when voltage is applied.”
The final element of the probe is the spectrometer, which utilizes infrared light to capture measurements. “To achieve a high measuring speed, we developed our own spectrometer with a broadband source to measure the spectrum of light in addition to its intensity.” The team chose infrared light to penetrate more deeply into skin since visible light limits imaging depth by 200 μ due to scattering.
The probe is capable of imaging 8 mm3 of tissue, 2 mm long x 2 mm wide x 2 mm deep, with a 2 μ resolution. Rolland explained, “We obtain multiple cubes of data, each being at a different focus of the lens. [Then] we use an algorithm to section out the focused region within those cubes and merge them together. Rolland’s team calls this technique Gabor domain optical coherance microscopy, which combines the high speed component of FDOCM with lateral resolution. Thus far, in human skin in vivo, the team has imaged 1 mm deep with a 2 μ resolution, although the probe could measure deeper based on variables such as the transparency of the skin, the wavelengths used, the type of tissue, etc.
According to Rolland, this device is currently used in the medical field to determine if skin lesions should be biopsied by identifying intact skin. In the future, it may be used to conduct optical biopsies of lesions.