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Assessing the importance of the root mean square (RMS) value of different waveforms to determine the strength of a dielectrophoresis trapping force
Author(s) -
Gilmore Jordon,
Islam Monsur,
Duncan Josie,
Natu Rucha,
MartinezDuarte Rodrigo
Publication year - 2017
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201600551
Subject(s) - root mean square , square root , trapping , square (algebra) , content (measure theory) , dielectrophoresis , value (mathematics) , waveform , physics , statistics , mathematics , materials science , nanotechnology , mathematical analysis , biology , quantum mechanics , ecology , geometry , voltage , microfluidics
Different fabrication technologies are now available to implement the electric field gradient required to induce a dielectrophoretic (DEP) force across a sample of interest [1]. However, the optimization of the polarizing waveform is still an understudied topic. Here we present a methodical comparison between the use of sinusoidal, square and triangular signals to polarize a DEP array for particle trapping. Limited work has been done in this area, and always in function of the application being developed [2–4]. It is known that the strength of the DEP force is proportional to the root mean square (RMS) value of the polarizing signal [5]. The RMS amplitude of sinusoidal, square and triangular signals is A √ 2 , A, and A √ 3 respectively, where A is the peak amplitude of the signal. Some authors reported that time-based differences, i.e. shape, amplitude, or frequency, in AC (alternating current) signals contribute to changes in DEP behavior [2–4]. We postulate that these changes are the result of the time-averaged RMS voltage, which normalizes the effect of time on changing AC signals. We show that the trapping of particles using positive DEP (pDEP) is approximately the same regardless of the shape of the polarizing signal; as long as the waveforms feature an equivalent RMS voltage magnitude. We characterized the trapping characteristics of 1.1 ± 0.12 m-diameter polystyrene particles (yellow-green fluorescent, Magsphere Inc.) on an array of 3D carbon post electrodes (100 m height by 50 m diameter). A microchannel made with double-sided pressure-sensitive adhesive contained the electrode array. The reader is referred to our previous publications to consult the fabrication details of these flow-through carbon-electrode DEP devices [6–9]. Particles were suspended in distilled water at a concentration of