Design and fabrication of a flexible dielectric sensor system for in situ and real-time production monitoring of glass fibre reinforced composites

Abstract

Dielectric analysis has attracted great attention in recent years for the monitoring of composite production processes because of its capability to be applied in situ and in real-time. However, to progress from lab to industry level, the sensor system should be as sensitive and reliable as possible, whereas its fabrication should be simple and cost effective. In this study, a dielectric sensor system based on interdigital electrodes was developed. The system was fabricated by flexible circuit board technology, which combines low cost per unit area and high extendibility with off-the-shelf electronic components. The sensor’s geometry was optimized through analytical expressions and finite element method to maximize its sensitivity. Four-wire interconnects were simultaneously fabricated with the sensor to minimize the measurement error. A system with a signal-to-noise ratio better than 55dB was successfully applied to monitor the production of glass fibre reinforced composites fabricated by vacuum assisted resin infusion process. The obtained data clearly shows the different key stages along the production process, proving the potential of the system.