Investigators from UCSF and UC Berkeley have just published an article at PloS ONE that discusses applicability data and design of a newly developed microscope-enabled mobile phone system, dubbed CellScope. We have covered CellScope on our pages before. The goal of this research is to equip clinicians with a small and cheap technology to image microorganisms and pathology specimens in remote places, for an instant diagnosis or for transmission of images to a central location, such as a regional medical center.
The engineers attached compact microscope lenses to a holder fitted to a cell phone. Using samples of infected blood and sputum, the researchers were able to use the camera phone to capture bright field images of Plasmodium falciparum, the parasite that causes malaria in humans, and sickle-shaped red blood cells. They were also able to take fluorescent images of Mycobacterium tuberculosis, the bacterial culprit that causes TB in humans. Moreover, the researchers showed that the TB bacteria could be automatically counted using image analysis software.
The engineers had previously shown that a portable microscope mounted on a mobile phone could be used for bright field microscopy, which uses simple white light — such as from a bulb or sunlight — to illuminate samples. The latest development adds to the repertoire fluorescent microscopy, in which a special dye emits a specific fluorescent wavelength to tag a target – such as a parasite, bacteria or cell – in the sample.
The researchers used filters to block out background light and to restrict the light source, a simple light-emitting diode (LED), to the 460 nanometer wavelength necessary to excite the green fluorescent dye in the TB-infected blood. Using an off-the-shelf phone with a 3.2 megapixel camera, they were able to achieve a spatial resolution of 1.2 micrometers. In comparison, a human red blood cell is about 7 micrometers in diameter.
The researchers pointed out that while fluorescent microscopes include additional parts, less training is needed to interpret fluorescent images. Instead of sorting out pathogens from normal cells in the images from standard light microscopes, health workers simply need to look for something the right size and shape to light up on the screen.
Article in PLoS ONE: Mobile Phone Based Clinical Microscopy for Global Health Applications…
Press release with video of the microscope in action: UC Berkeley researchers bring fluorescent imaging to mobile phones for low-cost screening in the field…
Side image: Fluorescent image of TB bacteria taken by the CellScope.
Flashback: CellScope for Rural Microscopy On The Go