Open Access

Synthetic and natural carbons are widely used as carrier for electrodes in electrochemical applications. They need to have a controlled morphology in order to facilitate mass and charge transport, so the process of film formation is of uttermost importance. Here we show, how carbons (after proper preconditioning) can be codeposited with an ionomer by electrophoretic deposition, a method that does allow full control of deposition conditions during the process. In view of potential applications, we focus on the direct deposition on proton conducting membranes. Ionomers and membranes applied are based on established per-fluorinated polyethylene with SO3H terminated side chains (PFSA). Conditions for reproducible deposition are reported in terms of optimal charge on the carbon particles, field strength in the deposition cell and necessary deposition times for a given film thickness. Additionally, a horizontal cell arrangement is suggested to avoid gravitational effects.

Optical sensors are often a combination of optical fibers or waveguides and sensitive layers which consist of organic or metal-organic dyes incorporated in a polymer or silica film which change their absorbance or photoluminescence (fluorescence or phosphorescence) properties due to interaction with the analyte molecules. The focus of this chapter is on the description of inorganic materials used in electrochemical sensors, because these found widespread applications in gas-sensors and ion-selective electrodes. The response of such sensors can be due to a change of inherent properties of the sensing material (conductivity, capacitance or permittivity) or a change of the measured current or voltage in an electrochemical cell (amperometric or potentiometric sensors).