Physical measurement methods for on-chip cell analysis

The analysis and sorting of biological cells in microfluidic chips has been one of the fastest growing sensor-research topics in the past few years. The characteristic scale of microfluidics devices (channel diameter from a few to some tens of micrometers) fits very well to the typical size of cells which makes them a very useful platform for the analysis and handling of cells. In addition, the integration of sensors and actuators into such microfluidics chips is a matured technology, allowing the design of numerous elements for the diagnosis of cells. Not only cell cultures are studied on a chip but also single cells, which yields more specific information, for example on the initiation of diseases. In addition to chemical analysis methods (e.g. ion selective electrodes or electrochemistry) also physical analysis methods can be applied to retrieve information from cells. A driving force to apply physical sensors is the potential of label-free analysis which makes the measurement faster and cheaper. In this contribution an attempt is made to give an overview of current physical measurement and actuating principles for the on-chip analysis of cells