A Simple Electrode Insulation and Channel Fabrication Technique for High-Electric Field Microfluidics

TL;DR

This paper presents a simple, robust electrode insulation method for high-voltage microfluidic applications, utilizing multi-dielectric layers to withstand electric fields up to 1MV/m, enabling advanced electrokinetic techniques.

Contribution

It introduces a novel multi-dielectric insulation technique that enhances electrode robustness and reduces defects in high-voltage microfluidic devices.

Findings

Insulation can withstand up to 1000 V across 10 μm channels.

Breakdown strength varies with sodium chloride concentration.

Effective adhesion technique improves channel sealing.

Abstract

A simple and robust electrode insulation technique that can withstand a voltage as high as $\mathrm{1000~V}$, which is equivalent to an electric field strength of $\sim 1MV/m$ across a $\mathrm{10~\mu m}$ channel filled with an electrolyte of conductivity $\sim 0.1~S/m$, 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.