The research was done by Drs. Dian R. Arifin, Leslie Y. Yeo and James R. Friend, of Monash University's Micro/Nanophysics Research Laboratory in the Department of Mechanical Engineering. The researchers' findings are published in the current issue of the new open-access journal Biomicrofluidics (http://bmf.aip.org).
Separating blood plasma from red blood cells, proteins and other microscopic particles is an essential step in many common medical tests, including those for cholesterol levels, drugs in athletes, blood types in donors and glucose levels in diabetics. Current testing requires samples to be taken in a doctor's office and sent off to a laboratory and analyzed with a large centrifuge, a process that can take several days.
In the new method, a tiny amount of blood enters a fluid chamber, and a needle tip is placed close to the surface of the blood at an angle. A voltage is applied to the needle, generating ions around its tip that repel the oppositely charged ions close to it. This creates an airflow known as "ionic wind" that sweeps across the surface of the blood, causing it to circulate. The microscopic particles in the blood travel in a downward spiral because of the needle's angle relative to the surface.
When the fluid begins to circulate, one might intuitively expect the microscopic particles such as red blood cells would be pulled to the outside wall of the chamber owing to centrifugal force. But because of a phenomenon called the "tea leaf paradox," the particles are instead pulled i
Source:American Institute of Physics