Miniaturized Flexible Interdigital Sensor for In Situ Dielectric Cure Monitoring of Composite Materials

This paper presents the design and fabrication of a miniaturized flexible capacitive sensor based on interdigitated structures and its embedding in carbon fiber reinforced plastics to measure the degree of curing during manufacturing. The substrate´s flexibility makes it possible to use the sensor to manufacture laminates. The array consists of 1024 gold electrodes with an electrode width and spacing of 3 μm creating an active area of 18.4 mm2. The sensor´s thickness is comparable with the carbon fiber´s (filaments´) thickness. A thickness of 6 μm interrupts the cross linking of the composite material only marginally. The sensor has been produced and embedded. Measurements confirm that it can effectively monitor the polymerization process.