A Microfabrication-Based Dynamic Array Cytometer

Original entry: Warren Lloyd Ung, APPHY 225, Fall 2009

"A Microfabrication-Based Dynamic Array Cytometer"
Joel Voldman, Martha L. Gray, Mehmet Toner, and Martin A. Schmidt.
Analytical Chemistry (2002).

Soft Matter Keywords

dielectrophoresis, dielectrophoretic trapping, single-cell assay

Figure 1: The Microfabrication-Based Dynamic Array Cytometer: (A) Schematic of the overall system, (B) a single dielectrophoretic trap, and (C) the microfabricated array of traps.

Summary

Voldman et al used microfabrication methods to construct an array of traps, which can be used to independently examine single cells in a programmable and controlled manner (see Figure 1). These traps use dielectrophoresis to confine cells within a defined area of a microfluidic flow device. Each trap consists of four metal posts, which extend into the flow channel. When coupled with an optical system, that probes the responses of cells in real time, this device provides a suitable basis for studying single cells. Cells can be sorted depending on whether they exhibit a desired fluorescent response; the chip additionally provides a dynamic capability to capture or discard cells based on these fluorescent indicators.

Figure 2: (A) The Dynamic Array Cytometer is shown in a fluorescence image. Green dots indicate cells captured by the traps. (B) Traces of the fluorescence signal of the cells indicate, that cells within the device remain stably confined over time, and can be released as desired.

Applications

Fluorescence markers are powerful tools for biological studies. Markers can be designed to pinpoint many aspects of cellular behaviour. Although flow cytometry methods allow cells to be sorted quickly based on fluorescence, this device adds the capability of examining and observing the dynamic behaviour of a particular cell over time. This may reveal behaviour, which is not observable during the short time scales required by typical methods of flow cytometry.

The development of this device also uses