Tiny Mobile Phone Microscope
My niece has worked in remote developing nations, in places like a tiny village in South Africa where the women have to walk several hours to fetch clean water. In order to travel to such areas, she had to take malaria medication and get a lot of vaccines — such as hepatitis A and B, yellow fever, typhoid, rabies, rubella, and diphtheria vaccines. HIV and Aids can also be prevalent. Unfortunately medical care and resources are often very limited in such isolated villages, where a doctor is many miles away and the villagers may not have access to vehicles or proper roads. To address this critical need, people are using new technology to bring the patients figuratively to the doctors. For example, medical data is acquired and then transmitted to a doctor or medical specialist elsewhere for offline assessment.
This field of telemedicine is growing rapidly. Some telemedical technology relies on the fact that cell phones are now used even in the developing world, as evidenced by extensive cell phone use after the recent earthquake in Haiti. Wireless phone technology has become significantly cheaper and the technical capabilities of cell phones is rapidly improving.
Aydrogan Ozcan, a research engineer at UCLA, has created a tiny microscope that is portable and lensless for telemedicine applications. The microscope attaches using a USB connection to a smart-phone, PDA or computer. This week his group published a paper describing in detail his latest, tiniest microscope. This minature microscope weighs just 46 grams (about the same weight as a large egg) and has dimensions of about 4 cm x 4 cm x 6 cm. It can image sub-cellular structures (with 1-2 micron resolution) over a 24 mm2 imaging area.
Microscopes normally use a lens to magnify the image of an object, where the image is generated by an electromagnetic (in optical microscopes) or electron (in electron microscopes) beam passing through the sample. However, standard microscopes are bulky and expensive, so they are generally used only in laboratories.
Ozcan’s lensless miniature microscope is instead based on digital in-line holography. It uses a simple light-emitting-diode (LED) and a compact digital sensor array to capture holographic images of blood samples or other fluids. A small chip is filled with a fluid sample, such as a blood smear, that is inserted into the microscope. The LED passes incoherent light through the sample, and the interference of the light waves that pass through the cells creates a hologram of each cell. The microscope digitally records these holograms, then rapidly reconstructs images of the cells. A compressed version of each holographic image can then be transmitted to hospitals elsewhere using wireless cellular networks, which have penetrated even the most remote corners of the world.
This portable microscope can accurately identify and count cells, including red blood cells, white blood cells, platelets, and T-cells (white blood cells whose counts are important for accurate diagnosis of AIDS). So this technology could help monitor diseases like malaria, HIV, and tuberculosis. It could also be used to test water quality following a disaster, such as a major earthquake or hurricane.
Ozcan’s microscope is also durable and easy to use. You just need to fill a chip with a sample and slide the chip into the slot in the microscope. The sample doesn’t need to be perfectly aligned in the microscope, so very minimal training is needed. It also uses cheap parts and a standard smart-phone. Plus the images are analyzed automatically by a computer, instead of requiring a trained medical technician. However, this analysis does have a potential down-side. Namely, the computer automatically identifies a cell by comparing the cell’s hologram to a cell hologram library, but I’ve seen little information on the development of this database.
Overall though this new tiny mobile phone microscope has great promise. It could become a very cost-effective tool for telemedicine applications. Next time my niece heads off to a remote village, maybe she can have a tiny microscope to attach to her smart-phone just in case?