For the fabrication of micrototal analysis systems (μTAS) methods of micropatterning, sealing, and for the manufacturability, as well as techniques for connecting the microstructures to the macroworld are of particular significance. The idea is to create a monolithic instrument which consists of an assembly of three-dimensional integrated modules (e.g. fluidic networks, electrical and optical sensors, microelectronic circuits) to support the advantage of efficient interconnections. To demonstrate the feasibility of an application specific lab-on-microchip, published in Ref.1, results obtained with a fabricated micro flow cytometer and monolithically integrated optical detectors based on amorphous silicon are reported. In this work, we use an a-Si:H pin diode for the optoelectronic detection of organic fluorescence sensors, namely anthracene derivatives, which are driven through the fluidic channel network hydrodynamically.