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 mu m creating an active area of 18.4 mm(2). The sensor's thickness is comparable with the carbon fiber's (filaments') thickness. A thickness of 6 mu m 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.