Researchers at Stanford University School of Medicine developed a cell sorting device, which they call an integrated microfluidics-waveguide sensor, that can sift through and measure the number of different types of white cells in a sample of blood.
Originally developed to detect severe combined immunodeficiency, or “bubble boy disease”, the researchers quickly realized that the technology can be used to help identify other, more common conditions. The technology behind the sensor is described in the latest issue of Biomicrofluidics.
More about the new technology from Stanford’s announcement:
The body has many types of white blood cells, each with different disease-fighting roles. White blood cell counts already help doctors diagnose some diseases and monitor treatment of others, including cancer and AIDS, but current cell-counting methods require fairly large blood samples and costly, slow equipment that can be operated only by trained laboratory technicians.
One possible application of the new sensor would allow doctors to solve a common, vexing problem: determining the cause of a runny nose. Instead of using the current trial-and-error method for diagnosing the problem, doctors could take a mucus sample from the patient in their office and measure the white blood cells present. Elevation of one type of white blood cells could implicate allergies, another cell type could point to a sinus infection and a third type of elevated cell count could suggest that the runny nose was simply due to the common cold.
The new sensor consists of a small, rectangular piece of glass impregnated with a strip of potassium ions. The potassium-impregnated glass acts as a “waveguide” — laser light shone into the strip of glass is transmitted down it in a specific way, and the light emitted from the far end of the waveguide can be measured with a light sensor.
To operate the detector, a patient’s fluid sample is mixed with antibodies specific for the particular type of white blood cell to be measured. Each antibody is attached to a tiny bead of magnetic iron. Then, the sample is injected in a small channel on top of the glass waveguide. A magnet under the glass traps the labeled cells in the channel. The iron beads block a bit of the laser light that would otherwise pass through the waveguide, and this reduced transmission is measured by the light sensor at the far side of the glass.
Abstract in Biomicrofluidics: Counting cells with a low-cost integrated microfluidics-waveguide sensor