Fabrication challenges and perspectives on the use of carbon‐electrode dielectrophoresis in sample preparation

Abstract

The focus of this review is to assess the current status of three-dimensional (3D) carbon-electrode dielectrophoresis (carbonDEP) and identify the challenges currently preventing it from its use in high-throughput applications such as sample preparation for diagnostics. The use of 3D electrodes over more traditional planar ones is emphasised here as a way to increase the throughput of DEP devices. Glass-like carbon electrodes are derived through the carbonisation of photoresist structures made using photolithography. These biocompatible carbon electrodes are not ideal electrical conductors but are more electrochemically stable than noble metals such as gold and platinum. They are also significantly less expensive than common electrode materials, both in terms of material cost and fabrication process. CarbonDEP has been demonstrated for the manipulation of microorganisms and biomolecules. This review is divided in three main sections: (i) carbonDEP fabrication process; (ii) applications using 3D carbonDEP; and (iii) challenges and perspectives on the use of carbonDEP for high-throughput applications.

Evaluating carbon-electrode dielectrophoresis under the ASSURED criteria

“…The fabrication of carbonDEP devices mainly consists of three important steps: photolithography of an epoxy photoresist (typically SU-8), carbonization of the patterned photoresist, and assembly of the resulting carbon microelectrodes with a microfluidic channel ( 29 , 30 ). Photolithography allows to pattern the precursor into both 2D and/or 3D shapes.…”

“…Furthermore, biosensors can be integrated to carbonDEP device to enable sample-to-answer functionalities in a single device. An integrated device featuring a series of electrode arrays optimized for different functionalities can be envisioned, where first array of electrodes can be used for DEP to enrich a targeted population, the next one for cell lysis to extract their intracellular components, one more DEP arrays for enriching a targeted molecule or organelle, and a last one for detecting specific target using carbon elements functionalized with aptamers or bacteriophages ( 30 ).…”

A critical review on the fabrication techniques that can enable higher throughput in dielectrophoresis devices

“…Tall, slender precursor structures with small diameter are preferred so their shrinkage does not significantly widen the gap between carbon electrodes. More details on the design of carbon electrodes have been published elsewhere by this author [81]. An advantage of using SU-8 photolithography is that it can yield high-density arrays of features with tailored cross sections and with small gaps in between them.…”