Cell analysis and clinical diagnosis are now becoming the largest fields of application for microchip-based analytical systems. The advantages of miniaturization include small sample and reagent volumes, smaller space requirements and size, easy operation and fast analysis time, as well as easy adaptation to custom needs. Another important advantage of the microchip-based cell analysis system is the ability to integrate successive steps in an analytical process on a single microchip. Common to all the described chip and sensor-processing technologies are the comparatively high fabrication costs, even in industrial fabrication lines. Screen printing may be an alternative, but the achievable structural resolution is suboptimal for some of the required sensor functions. For many screening applications, the monitoring sites have to be arranged in high-density arrays to create a basis for sound data statistics. There are increasingly successful attempts toward single-cell analysis in microdevices, allowing a statistical treatment of data derived from single cells.