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Article

Active, Reactive, and Apparent Power in Dielectrophoresis: Force Corrections from the Capacitive Charging Work on Suspensions Described by Maxwell-Wagner’s Mixing Equation

Department of Biophysics, University of Rostock, Gertrudenstr. 11A, 18057 Rostock, Germany
Academic Editor: Antonio Ramos
Micromachines 2021, 12(7), 738; https://doi.org/10.3390/mi12070738
Received: 18 May 2021 / Revised: 14 June 2021 / Accepted: 21 June 2021 / Published: 23 June 2021
(This article belongs to the Special Issue Micromachines for Dielectrophoresis, Volume II)
A new expression for the dielectrophoresis (DEP) force is derived from the electrical work in a charge-cycle model that allows the field-free transition of a single object between the centers of two adjacent cubic volumes in an inhomogeneous field. The charging work for the capacities of the volumes is calculated in the absence and in the presence of the object using the external permittivity and Maxwell-Wagner’s mixing equation, respectively. The model provides additional terms for the Clausius-Mossotti factor, which vanish for the mathematical boundary transition toward zero volume fraction, but which can be interesting for narrow microfluidic systems. The comparison with the classical solution provides a new perspective on the notorious problem of electrostatic modeling of AC electrokinetic effects in lossy media and gives insight into the relationships between active, reactive, and apparent power in DEP force generation. DEP moves more highly polarizable media to locations with a higher field, making a DEP-related increase in the overall polarizability of suspensions intuitive. Calculations of the passage of single objects through a chain of cubic volumes show increased overall effective polarizability in the system for both positive and negative DEP. Therefore, it is proposed that DEP be considered a conditioned polarization mechanism, even if it is slow with respect to the field oscillation. The DEP-induced changes in permittivity and conductivity describe the increase in the overall energy dissipation in the DEP systems consistent with the law of maximum entropy production. Thermodynamics can help explain DEP accumulation of small objects below the limits of Brownian motion. View Full-Text
Keywords: DEP force in narrow volumes; capacitor charge cycle; micro-fluidic volumes; DEP trajectories; 2D and 3D modelling; DEP-induced polarizability increase; conditioned polarization; lossy dispersive materials; thermodynamics; Rayleigh’s dissipation function; law of maximum entropy production (LMEP) DEP force in narrow volumes; capacitor charge cycle; micro-fluidic volumes; DEP trajectories; 2D and 3D modelling; DEP-induced polarizability increase; conditioned polarization; lossy dispersive materials; thermodynamics; Rayleigh’s dissipation function; law of maximum entropy production (LMEP)
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MDPI and ACS Style

Gimsa, J. Active, Reactive, and Apparent Power in Dielectrophoresis: Force Corrections from the Capacitive Charging Work on Suspensions Described by Maxwell-Wagner’s Mixing Equation. Micromachines 2021, 12, 738. https://doi.org/10.3390/mi12070738

AMA Style

Gimsa J. Active, Reactive, and Apparent Power in Dielectrophoresis: Force Corrections from the Capacitive Charging Work on Suspensions Described by Maxwell-Wagner’s Mixing Equation. Micromachines. 2021; 12(7):738. https://doi.org/10.3390/mi12070738

Chicago/Turabian Style

Gimsa, Jan. 2021. "Active, Reactive, and Apparent Power in Dielectrophoresis: Force Corrections from the Capacitive Charging Work on Suspensions Described by Maxwell-Wagner’s Mixing Equation" Micromachines 12, no. 7: 738. https://doi.org/10.3390/mi12070738

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