Miniaturised flow-through cell with integrated capacitive EIS sensor fabricated at wafer level using Si and SU-8 technologies

Eight different miniaturised flow-through cell configurations with integrated capacitive EIS (electrolyte–insulator–semiconductor) structures have been fabricated at wafer level. The EIS structures have been prepared by means of Si technique (electron-beam evaporation, thermal dry oxidation) and serve as pH sensors. The channels for the miniaturised flow-through cell have been manufactured in SU-8 technique (spin-coating, exposure, developing, lift-off). The microcells have diameters of 200–2000 μm and volumes of 0.3–5 μl. The sensitive areas in the channels are ranging from 1.6 to 25 mm2. For the realisation of a biosensor, the enzyme penicillinase has been immobilised into the channels on the EIS sensor chip. The electrochemical characterisation of the sensor set-up has been performed by capacitance/voltage (C/V) and constant capacitance (ConCap) mode, respectively.