Fluorescent biomarkers inside the skin are used to track a number of biochemical reactions for medical therapy and diagnostics. A team at Verily Life Sciences working with UCLA researchers have designed a mobile microscope that can monitor and detect these biomarkers with a high level of sensitivity.

Weighing in at less than a one-tenth of a pound, the new microscope is light and small enough to be worn around a person’s bicep, or other parts of the body. It might be possible to use technology like this in a point of care setting, or for continuous patient monitoring at home in the future.

Various medical therapies such as drug delivery and cancer detection routinely use fluorescent biomarkers. Recently, new opportunities for noninvasive sensing and measuring of biomarkers through the skin have been created by the emergence of new biocompatible fluorescent dyes.

Being able to detect artificially added fluorescent objects under the skin is not easy. Auto fluorescence is a process used by melanin, collagen and other biological structures to emit natural light. Numerous methods have been investigated to solve this problem in the past. Different sensing systems were used. Most are difficult to make, expensive or are not small enough to be used as an imaging system that can be worn.

The researchers first designed a tissue phantom, which is an artificially created material that imitates human skin’s optical properties to test the mobile microscope. Properties including scattering, auto fluorescence and absorption were mimicked with the tissue phantom. A volume of about one hundredth of a microliter of the fluorescent dye was injected into a micro-well. The well was then implanted half a millimeter to 2 millimeters from the surface of the tissue phantom. This is deep enough to reach tissue fluids and blood in a practical situation.

The fluorescent dye was measured by using a laser to hit the skin at an angle. The fluorescent image at the surface of the skin was then captured via the wearable microscope created by Ozcan and his team. After uploading the image to a computer, it was processed using a custom designed algorithm that separates the target fluorescent signal from the auto fluorescence of the skin digitally. This is done at an extremely sensitive (parts per billion) level of detection.

Ozcan notes that their imaging system can distinguish between a number of tiny bio sensors placed next to each other inside the skin. The embedded sensors inside the skin can be monitor in parallel. Potential misalignments of the wearable imager can be identified and corrected to quantify a group of biomarkers continuously.

Full study has been outlined in the journal ACS Nano.

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