Contactless dielectrophoresis: a new technique for cell manipulation

Abstract

Dielectrophoresis (DEP) has become a promising technique to separate and identify cells and microparticles suspended in a medium based on their size or electrical properties. Presented herein is a new technique to provide the non-uniform electric field required for DEP that does not require electrodes to contact the sample fluid. In our method, electrodes are capacitively-coupled to a fluidic channel through dielectric barriers; the application of a high-frequency electric field to these electrodes then induces an electric field in the channel. This technique combines the cell manipulation abilities of traditional DEP with the ease of fabrication found in insulator-based technologies. A microfluidic device was fabricated based on this principle to determine the feasibility of cell manipulations through contactless DEP (cDEP). We were able to demonstrate cell responses unique to the DEP effect in three separate cell lines. These results illustrate the potential for this technique to identify cells through their electrical properties without fear of contamination from electrodes.

Enhanced contactless dielectrophoresis enrichment and isolation platform via cell-scale microstructures

“…23,25 Devices have been used to successfully sort cells with different electrical/geometrical properties, such as live and dead cells, but sorting cells with small variations in their electrical properties is challenging. Typically pillars that distort the electric field have a much larger diameter (100 lm) than cells (less than 20 lm) and the dielectrophoretic forces accumulate several cells around pillars.…”

“…Deep reactive-ion etching (DRIE) was used to fabricate the main channel as described in detail in Shafiee et al 25 AZ 9260 (AZ Electronic Materials, Somerville, NJ) photoresist was spun onto a silicon wafer and soft-baked. The wafer was then exposed to UV light through a printed glass mask.…”

“…25,26 Dielectrophoretic separation is based on bioelectrical cell properties and is independent of the cells' genotype. Classical DEP uses metal electrodes to create a non-uniform electric field; at the edges of the electrodes, the electric field density can be locally high, damaging the cells.…”

“…The method of cDEP utilizes insulating pillars to distort the electric field and a thin insulating membrane separating the electrode from the cell suspension to allow for maximum density of the field in the channel while maintaining the electric field at a low enough magnitude to minimize electrical damage to the cells. 25,26,29 In classical DEP, a gap between electrodes is typically in the range of 0.1 mm, while for iDEP and cDEP they are a few millimeters apart, necessitating a high-voltage AC signal source.…”

Multifunctional, inexpensive, and reusable nanoparticle-printed biochip for cell manipulation and diagnosis

“…The platform is designed as a contactless platform, where the electronic apparatuses are not in contact with the biological samples. This eliminates the possibility of bubble formation, fouling, and cross-contamination of the chip, all of which are common issues in most current microfluidics-based LOC cell manipulators (3,46). Lifetime, as another important feature of any POC platform, is improved in our device by designing the flexible electronic apparatus as detachable components from the disposable microfluidic biochips.…”