One of the most commonly ordered blood tests is the complete blood cell count. Currently this requires the use of a lab with bulky, expensive equipment and trained technicians. But now, a new biosensor based on a microfluidic biochip promises to bring blood count to the bedside.
The innovation could make the diagnosis and screening of hundreds of diseases and treatments faster, easier and cheaper, suggest researchers from the University of Illinois in the US.
One of the most compelling applications for this test is in resource-limited settings, where laboratory tests are often inaccessible due to cost, poor prevalence of laboratory facilities and the difficulty of follow-up upon receiving results that take days to process.
The team believes the new technology can be developed into a portable blood cell counter that gives results in minutes from a single drop of blood, without the need for trained professionals to operate it.
The complete blood cell count typically includes measures of white blood cells, red blood cells, platelets and hemoglobin. In their paper, the researchers describe how their biosensor yields counts of red blood cells, platelets and white blood cells from only 11 microliters of blood.
The white blood cell count is used to assess the body's ability to fight infection. It includes a count of white blood cells, plus a breakdown of the relative proportions of different types of white blood cells.
The biosensor electrically counts the different types of blood cells based on their size and membrane properties. For the white blood cell and differential count, the device used 10 microliters of blood. It picks out and destroys red blood cells and individually counts the remaining white blood cells. Then, specific types of white blood cells - for example, neutrophils - are counted using multi-frequency analysis, which is sensitive to different membrane properties.
For the red blood cell and platelet count, the biosensor uses 1 microliter of whole blood. After the sample is diluted with saline on the chip, the cells are counted electrically. The total time to obtain the results is under 20 minutes.
Researchers believe that commercialization of their technology could result in even patients performing the test in the comfort of their homes and sharing the result with their doctor through electronic means. The team is already developing a portable prototype of the cell counter with a hand held reader that they estimate could do a blood test for less than $10, appreciably down from the current price of around $100.