(441f) Dielectrophoretic Responses of Human Erythrocytes

Medical microdevices, which use small sample sizes for potentially rapid diagnosis, are currently being developed to determine human blood type based on the erythrocyte response to an alternating current dielectrophoretic field. The blood typing system of interest is the ABO-Rhesus factor system, which consists of eight blood types (A+, B+, AB+, O+, A-, B-, AB- and O-) differing by the terminal groups of the polysaccharides bound to the blood cell membrane. This work discusses the response of ABO human erythrocytes to an externally applied AC dielectrophoretic field in a custom-fabricated microdevice at 1kHz and 1MHz frequencies. At the 1kHz frequency it is observed that the erythrocytes translate very little in the field, but swell and eventually rupture. This phenomena was quantified by manually tabulating the number of unruptured cells remaining in still frame images taken from a Zeiss Axiovert inverted video microscope. The following dependencies were tested: field intensity, frequency, blood type, donor, and microdevice. Variation in rupturing rate between many of the blood types tested demonstrated that B+ blood ruptures significantly more cells in 15 minutes than any other blood type. Further, the addition of the Rhesus factor to any given ABO blood type caused a decrease in the percentage of cells ruptured over the experimental period. At the 1 MHz frequency, a pearl chain effect was observed for the majority of the blood types. This phenomenon was quantified with image intensity analysis and cell particle tracking. These results provide evidence that the membrane polysaccharides contribute to cell polarizability in a dielectrophoretic field suggesting that this electrokinetic effect may be harnessable for differentiation between blood types in the ABO typing system.