An integrated sensor system for monitoring washing processes

This thesis deals with the development, realisation and testing of an array of sensors for determining the state of a washing process. To combine the sensors in a single array, some techniques are used. First, the sensors which are integrated are chosen with respect to their fabrication materials and technique. By matching these, the sensors could be combined into a single multi-purpose structure. A reduction of the number of connecting wires is the result, and the single structure will measure all parameters at the same spot in the solution. In addition, together with sensors, also actuators are integrated. This enables the possibility of performing stimulus-response measurements. Such experiments are based on recording the response of solution components on an imposed local disturbance. Sometimes, such dynamic measurements give new information on the solution. Finally, the combination of sensor readings, together with the results of the stimulus-response measurements, yields a set of data which can be used for smart interpretation and decisions. The final result is a system consisting of a small noble metal structure, applied on a carrier, with a size of only one square millimetre. By scheduling this structure in several operational modes, the following washing parameters can be measured: temperature, bleach activity, electrolyte conductivity, movement of the washing water and the temperature dependency of the electrolyte conductivity. The latter one can give information on the individual types of charged particles in the solution. Finally, some suggestions are given in order to implement washing parameters that are missing in the measurable set of variables.