Image by PLoS One

A mobile phone with microscope attachment.

Bulky, expensive microscopes help diagnose tuberculosis, sickle cell disease and malaria. In the developing world diagnosis is hampered by lack of equipment and difficulty accessing remote and rural areas.

If you can’t bring the people to the microscope, then bring the microscope to the people.

Daniel Fletcher and his colleagues at the University of California in Berkeley developed an attachment to a mobile phone, allowing it to be used as a portable microscope powerful enough to see blood cells and diagnose disease. Images are captured using the phone’s built in camera. Analysis and diagnosis can be made on the spot, or the image can be e-mailed from the phone to a clinic for more detailed examination.

The resolution of the device is about 1.2 micrometers (µm), good enough to see many different types of cells. Red blood cells are 7-8 µm in diameter; a human hair is between 60 and 120 µm wide.

What makes this even more impressive is that the team did not modify the mobile phone itself, a Nokia N73. They used the phone’s built-in camera (3 megapixels) and the phone’s photo capture software and settings. They could not control shutter speed or aperture and had limited control over exposure conditions.

Image by PLoS One

A human blood sample viewed with a mobile phone microscope. Arrows point to sickle-shaped red blood cells, a sign of sickle cell disease. The white scale bar (bottom right) is 10 µm long.

Despite these limitations, the mobile phone microscope appears to be able to detect misshapen red blood cells (a sign of sickle cell disease) and malaria-infected blood.

Fletcher’s team was also able to detect tuberculosis bacteria in sputum using fluorescence microscopy, a technique that normally requires an expensive and delicate light source and filters. Instead the scientists used a rugged LED as a light source and incorporated the filters into their device. After staining a blood sample with a fluorescent dye that specifically sticks to tuberculosis bacteria, you shine blue light on the specimen, and the bacteria will glow green. This green glow is very dim, requiring filters to insure that only green light reaches the camera.

Image by PLoS One

(a) Fluorescence image of Auramine O-stained TB sputum sample. (b) Enlarged view of two tuberculosis bacilli from red-outlined area in (a). Scale bars are 10 µm long in (a), 1 µm long in (b).

In the future, installing standard imaging software on the phone will allow users to count the number of tuberculosis bacteria in a sample automatically.

Fletcher and his colleagues seem to be following a standard model for commercializing their invention, which is to sell it in the developed world and use the profits to provide the device free, or at low cost, in the developing world. (Check out the award-winning nonprofit company Diagnostics For All to learn about an unconventional approach to commercialization.)

Ideas include using the device to count blood cells in patients undergoing chemotherapy for cancer treatment, which often make patients more susceptible to infections. Using the mobile microscope to perform routine cell counts at home would reduce the number of hospital visits, reducing exposure to pathogens.

Here’s another use: a microscope for children. Toy science sets abound, but microscopes are difficult to use in the field. To encourage a young biologist, provide your child with this microscope attachment to his or her mobile phone. In addition to texting friends, your child can now examine plants and bugs up close in the field. This could be a great way to instill a love of science and the natural world.

Source: Breslauer, D., Maamari, R., Switz, N., Lam, W., & Fletcher, D. (2009). Mobile Phone Based Clinical Microscopy for Global Health Applications PLoS ONE, 4 (7) DOI: 10.1371/journal.pone.0006320