Researchers at UCLA have developed a cell phone–based imaging cytometry device, which they built with a very simple optical design that is very cost-effective and easy to operate and could be used in resource-limited regions. The optofluidic platform integrates imaging cytometry and florescent microscopy that can be attached to a cell phone. The resulting device can be used to rapidly image body fluids for cell counts or cell analysis.
Flow cytometry is a technique for counting and examining cells, bacteria and other microscopic particles. Conventional flow cytometers are large and cost tens of thousands of dollars, and are thus not practical when resources are limited. The device created by the researchers uses a simple lens, a plastic color filter, 2 LEDs and basic batteries. In total it weighs 18 grams and costs less than five dollars. This is how the technique works (from the press release):
The microfluidic assembly is placed just above a separate, inexpensive lens that is put in contact with the cell phone’s existing camera unit. This way, the entire cross-section of the microfluidic device can be mapped onto the phone’s CMOS sensor-chip. The sample fluid is delivered continuously through a disposable microfluidic channel via a syringe pump.
The device is illuminated from the side by the LEDs using a simple butt-coupling technique. The excitation light is then guided within the cross-section of the device, uniformly exciting the specimens in the imaging fluid. The optofluidic pumping scheme also allows for the use of an inexpensive plastic absorption filter to create the dark-field background needed for fluorescent imaging.
In addition, video post-processing and contour-detection and tracking algorithms are used to count and label the cells or particles passing through the microfluidic chip.
The researchers demonstrated the ability of their device to measure the density of white blood cells in human whole-blood samples (used in leukemia, HIV and bone marrow deficiencies) with comparable efficacy to a traditional flowcytometer. Other potential applications of this technique include counting waterborne parasites for water-quality monitoring. The research is published online in the journal Analytical Chemistry.