Aerosol-Deposition-Derived Graphite Thick Films for Electrochemical Sensors

Disposable electrochemical (EC) sensors are usually manufactured by screen printing and post-deposition temperature curing of the sensor's components. However, complete removal of an organic vehicle requires curing at temperatures of a few hundred °C, which can lead to electrode-substrate incompatibilities and limit the choice of material. In this work, graphite thick-film electrodes without additives were deposited on polyimide substrates at room temperature using the aerosol deposition method. The resulting thick films have good adhesion, a defect-free surface, a thickness of a few micrometers, a root-mean-square roughness of 0.68 μm and sheet resistance of 27 ohm/sq. Scanning electron microscopy of the film surface shows good particle compaction. The X-ray diffraction analysis shows no peak broadening of the graphite thick films, which indicates a different deposition mechanism than that normally observed for ceramic powders. The EC properties of graphite working electrodes were evaluated using cyclic voltammetry. The graphite films show low capacitive current of 0.114 mA, good reversibility of redox process, high EC active surface area of 1.44 cm 2 /cm geo 2 and standard heterogeneous electron transfer rate constant of 0.0019 cm·s –1 . The aerosol-deposited graphite thick-film electrodes show potential for the EC detection of a broad range of chemicals