Mobile Phone microscopy

RESEARCHERS at the University of California, Berkeley have developed a microscope attachment which enables a standard mobile phone with a camera to be used for high-resolution clinical microscopy. Daniel Fletcher and his colleagues describe the CellScope in a paper published today in the open access journal PLoS One, and demonstrate that it can be used to capture high quality bright field images of the malaria parasite and sickle blood cells, as well as fluorescence images of cells infected with the bacterium that causes tuberculosis. The device could potentially become an important tool for medical diagnostics in the developing world, where resources are limited and laboratory facilities scarce, but where mobile phone networks are ubiquitous.

The working prototype shown here consists of a compact optical microscope mounted onto a Nokia N73 mobile phone equipped with a 3.2 megapixel camera. With cheap eyepieces and objective lenses, the device has a magnification of up to 50X and an estimated resolution of 1.2 µm (micrometres, or thousandths of a millimeter). This is sufficient for direct observation of abnormally-shaped red blood cells which are characteristic of sickle-cell anemia (below left) and of cells infected with Plasmodium falciparum, the parasite that causes malaria. By attaching filters which block out background light and a simple light-emitting diode (LED) which emits light of a specific wavelength, the CellScope can also detect, in samples of sputum, the green fluorescent dye which is used to stain cells infected with Mycobacterium tuberculosis (below right).

Using CellScope, minimally trained health care workers could therefore capture images from samples obtained from patients, and transmit them wirelessly to a clinic so that they can be examined properly by an expert diagnostician. The evaluation of samples could also be performed in real-time whilst the patient is still in the presence of the health care worker, by treating samples with rapid staining techniques and then using a specialized Java-based image processing and analysis program called ImageJ for automated sample counting, so that, for example, the number of bacteria present in a sample can be determined almost immediately.
The device could be produced very cheaply as it uses simple components and expands on the capabilites of standard mobile phones while using the existing communication infrastructure. The use of LEDs - which have a lifespan of about 50,000 hours - makes it particilarly suited to clinical applications in the developing world as well as in rural areas, where replacement parts might be expensive or unavailable. CellScope could also provide remote access to digitized health records, and would be amenable to epidemiological studies, using triangulation or global positioning system location data, such that outbreaks could be monitored as they happen.