CMOS single cell dielectrophoresis cytometer

Abstract

An integrated dielectrophoresis cytometer has been designed and implemented using a standard 0.35μm CMOS technology. This design makes use of differential ring oscillators. The frequency difference between the two oscillators, in presence of a cell, is detected by an XOR gate. The frequency difference is then measured by a frequency counter. This sensor has ∼14aF capacitance sensitivity at ∼1.4GHz. It is used for detection of 10–20μm polystyrene spheres and Chinese Hamster Ovary cells using coplanar microelectrodes on top of the CMOS chip. The design demonstrates that it is possible to differentiate between particles experiencing an altitude change resulting from either a positive or negative dielectrophoretic force in a microfluidic channel. The total area occupied by the DEP system is 0.6mm2. This sensor can be used in high throughput applications with a density of more than 160DEP sensor units in 1cm2. The sensor integrates all the required parts of a DEP cytometer -excluding the pumping system and frequency counter-, making a semi-integrated lab on chip system for single cell detection and analysis.