Capacitive Touch Dielectric Constant Validation

This research project aims to validate a model equation proposed by the capstone client for predicting the sensitivity factor of multi-layer fascias used in capacitive touch sensing devices. Capacitive touch sensing has changed the face of industrial design in products such as cell phones, personal computers, consumer electronics, automobiles, and household appliances. This research would be quantifying error and variation of experimental measurements in comparison to the client's estimations of sensitivity factor (the ratio of relative permittivity to thickness). The equation is currently used to design touch sensors, and if inaccurate, can lead to poorly functioning control panels. Experiments will measure the capacitance of various glasses (soda-lime, ceramic) and plastics (acrylonitrile butadiene styrene, polyvinyl chloride, polyester, polycarbonate) to independently and jointly evaluate their relative permittivity and sensitivity factors. The obtained values will then be compared with model predictions. An apparatus was built to effectively measure the capacitance of the sample layers listed above with various thicknesses in the normal range of industrial utilization of 1.5 mm-3.5 mm. The dependency of this device has been scrutinized with precision and accuracy tests to accelerate the further stages of the project. After completion of measurements and data collection via this designed system, the perceived phenomenon will be compared with the theoretical data along with the data retrieved from the client. Therefore, engineers will have access to experimental data, interpretations, and recommendations on the reliance of the equation. Results will have a robust impact on either stabilizing confidence in the utilization of the model equation or taking precautions if a higher percentage of error is confirmed.