A simple electrode insulation and channel fabrication technique for high-electric field microfluidics

Abstract

A simple and robust electrode insulation technique that can withstand a voltage as high as 1000 V, which is equivalent to an electric field strength of ∼ 1MV /m across a 10 μm channel filled with an electrolyte of conductivity ∼ 0.1 S/m, i.e., higher than sea water’s conductivity, is introduced. A multi-dielectric layers approach is adopted to fabricate the blocked electrodes, which helps reduce the number of material defects. Dielectric insulation with an exceptional breakdown electric field strength for an electrolyte confined between electrodes can have a wide range of applications in microfluidics, like high electric field strength-based dielectrophoresis. The voltage-current characteristics are studied for various concentrations of sodium chloride solution to estimate the insulation strength of the proposed materials, and the breakdown strength is calculated at the point where the electrical insulation failed. A detailed adhesion technique is also demonstrated, which will reduce the ambiguity around the fabrication of a sealed channel using SU-8

Anomalous, dielectrophoretic transport of molecules in non‐electrolytes

“…Figure 1 is the schematic of the experimental setup used to study the dielectric polarization‐based effect of an externally applied alternating current (AC) E‐field on a fluorescein 5(6)‐isothiocyanate (FITC)‐methanol solution of an initial concentration 0.1 mM, which is confined between two electrodes in a microfluidic channel. The fabrication of the microfluidic channel is based on the principle of photolithography discussed below [27]. The FITC‐methanol solution is prepared by mixing FITC, ≥ 90%, (supplied by Sigma‐Aldrich) in Methanol, and anhydrous ≥ 99.8%, (supplied by Macron Fine Chemicals).…”