(a) Dielectric relaxation mechanism for PS beads showing cases when (i) particle polarization occurs at a static frequency, (ii) τMW is shorter than the slow frequency sweep rate (τΔFS) allowing the bead interface time to polarize in response to the nonuniform AC field, and (iii) τMW is longer than the τΔFS for fast frequency sweep rates and the bead interface does not have time to fully polarize. (b) Schematic of the quadrapole electrodes micro patterned onto a glass slide, and (c) microdevice with PDMS fluidic layer bonded above the quadrapole electrodes silver epoxied to copper leads.
(a) nDEP behavior of 6 μm PS beads suspended in E-pure H2O 2.5 × 10−4 S/m and 250 Vpp/cm 0.0063, 0.056, and 0.17 MHz/s sweep rates from 0.010 MHz to 1.0 MHz. (b) Raw intensity profile of PS beads in the center nDEP region (boxes shown at 0.20 MHz) at 0.0063 MHz/s sweep rate. Inset is a calibration of intensity per bead. (c) Clausius-Mossotti factor for the PS beads from 0.010 MHz to 2.0 MHz at three conductivities of 2.5 × 10−4, 1.0 × 10−3, and 1.0 S/m. PS bead assembly at slower frequency sweep rates track static frequency responses while 0.056 MHz/s illustrates transitional behavior and frequency sweeps above 0.17 MHz/s substantially lag the true static frequency DEP responses.
(a) 6 μm PS beads nDEP intensity profiles for 0.00080, 0.0063, and 0.056 MHz/s and static steady state measurements (black diamonds). Intensity analysis captures bead assembly to the quadrapole center with transient and SS regions. The slowest frequency sweep rate of 0.00080 MHz/s best predicts the static DEP responses. (b) Bead assembly profiles for 0.0063 (n = 8) and 0.17 MHz/s (n = 7) with 95% confidence upper and lower limits shown as dashed lines. (c) Transient slope comparison for static frequencies (0 MHz/s) as well as frequency sweeps. (d) Comparison of static frequency and frequency sweep PS bead velocities from 0 to 50 s. 0.00080 MHz/s results are consistently similar to the static frequency results.
(a) nDEP behavior of RBCs suspended in 0.1 S/m dextrose buffer and 250 V/cm at 0.00080 MHz/s, 0.0063 MHz/s, and 0.056 MHz/s sweep rates from 0.010 MHz to 0.50 MHz. (b) RBCs nDEP intensity profiles for 0.00080, 0.0063, and 0.056 MHz/s and static measurements. (c) 0.00080 and 0.056 MHz/s RBC assembly profiles n = 8, with 95% confidence interval upper and lower limits shown as dashed lines.
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