Combined microchannel-type erythrocyte deformability test with optical tweezers: I. Basic principles

In this article, we report a novel combined microchannel-type erythrocyte deformability test with optical tweezers which can enhance the level of sensitivity with respect to the detection of cancerous diseases. To demonstrate the feasibility of the combined method, we introduce three major parameters, the transit velocity, a modified elongation index, and the shape recovery time of a single erythrocyte in a specifically confined region under different powers of an infrared laser. These parameters are geometrically determined and experimentally evaluated for a special blood-related disease, leukemia. The results support this method has a good detection sensitivity enough to pinpoint a minor difference in the deformability between individual erythrocytes. Furthermore, such a complementary combination of optical tweezers with microfluidic structures will be helpful for comprehensively understanding what significant effect the mechanical properties of erythrocytes have on the multiple chemical reactions inside a living erythrocyte.