FIG. 2.

Predicted DEP response, as described by $\Re ({\tilde{f}}_{\text{CM}})$, of Capan-1 (solid line), PANC-1 (dashed line), BxPC-3 (dashed-dotted line), and PBMCs (dotted line) as a function of applied electric field frequency. Cells were modeled as single-shelled dielectric spheres, described by Eqs. (2) and (3). In a diluted PBS suspending medium with σ_m = 0.07 S/m, the crossover frequency was experimentally determined to be approximately 140 kHz for Capan-1, 120 kHz for PANC-1, 140 kHz for BxPC-3, and 400 kHz for PBMCs. Because the DEP force is weak in these frequency ranges and therefore difficult to observe, our crossover frequency estimates all have an uncertainty of ±10 kHz. These empirical measurements, combined with Eq. (3), corresponded to specific membrane capacitance values of C_membrane = 13.5 mF/m² for Capan-1, C_membrane = 14.5 mF/m² for PANC-1, and C_membrane = 15 mF/m² for BxPC-3, and C_membrane = 7.5 mF/m² for PBMCs in the dielectric shell model. At 50 kHz, cancer cells and blood cells both exhibit a nDEP response; at 200 kHz, however, cancer cells exhibit a pDEP response whereas PBMCs still exhibit a nDEP response.