(65b) Dielectrophoretic Characterization of Red Blood Cells

Medical microdevices have been touted as the doctor's ?toolkit of the future' for their potential ability to perform a variety of diagnostic tasks while utilizing only a single drop of blood. This work describes a unique lab-on-a-chip device which performs blood sample preparation via rapid cell rupture to facilitate access to intracellular biomarkers. Traditional rupturing is accomplished via chemical lysis, which can leave unwanted chemicals in microdevice channels and interfere with subsequent separations, purifications, and analysis of desired proteins or other biomarkers. A recent alternative advanced by our lab group is rupturing the blood cells via dielectrophoresis; it is chemical free and entirely field dependent, so the intracellular contents of the red blood could be subsequently analyzed on the same chip. Rupturing behaviors in 1 to 1.3 kHz dielectrophoretic fields were quantified as a function of frequency, concentration and age for the eight blood types in the ABO typing system (A+,A-,B+,B-,AB+,AB-,O+,O-). Frequency was tested at 1 kHz, 1.15kHz and 1.3kHz. Concentration was tested at 60:1 and 40:1 volume to volume ratio of phosphate saline buffer and blood. Age dependency was tested by conducting rupturing experiments of the cells approximately every three days after blood donation. Erythrocyte rupturing was quantified by examining the still frames of video of ruptured red blood cells to determine the rupture rate. Rupture times increased with increasing frequency. Rupture rate changed with age and concentration and there was a large variability in the rupturing rate based on age and blood type. Experiments are complimented with theoretical examination of the membrane stabilities leading to cell lysis. The frequency range that induces cell rupture is thought to be driven by the Maxwell-Wagner membrane relaxation. This theory has been re-examined in the context of dielectrophoretic field driven resonance to model the membrane instabilities observed in experiments. This work would advance and simplify medical microdevices by enabling one step lysis in line with separation, purification, and analysis for fully integrated diagnostic blood tests.