Microfluidic systems in PCB technology

In this paper a technology for the production of microfluidic systems is presented. In an overview the design and properties of produced fluidic elements are described. The basic element is a thermal driven micro pump using FR4 as basic material. A design of a pressure sensor in PCB using polyimide membranes demonstrates how to overcome problems with bad material properties like thermal expansion coefficient and the dependence of elastic constant on humidity of polyimide. The compensation of the pressure force with electrostatic force is one possibility for the elimination of material properties of membrane. The ability of the technology to integrate microfluidic elements, optical sensors and electronics in a monolithic PCB-stack is demonstrated by a development of a flow-injection-analysis (FIA). This analysis system contains two micro pumps, one fluid mixer, one optical detector, and one reservoir for the fluidic reagent and, of course, the electronics for the amplification of sensor-signals and the control unit for pumps. The correct functionality of the PCB-FIA is demonstrated by the detection of iron (III) ions using the reagent Thiocyanat.