Fabrication and performance of capacitive humidity and strain sensors that incorporate 3D-printed nanocomposite electrodes

• Published in: Sensors international 2024, Vol.5, p.100272, Article 100272
• Main Authors: Matsalis, Stefanos, Paterakis, George, Koutroumanis, Nikos, Anagnostopoulos, George, Galiotis, Costas
• Format: Article
• Language: English
• Subjects: Graphene oxide; Humidity; Interdigitated electrodes; Sensing; Strain
• ISSN: 2666-3511; 2666-3511
• DOI: 10.1016/j.sintl.2023.100272

This work reports on advances in capacitive humidity and strain sensor technologies through the development of state-of-the-art 3D-printed Interdigitated Electrodes (IDEs) coated with a unique GO/ PVA coating. These IDEs are constructed using a novel composite filament of MWCNTs and polylactic acid (PLA) that offer superior flexural strength and electrical properties compared to conventional polymer matrices.We show that the GO/ PVA coating appears to be sensitive over the full range of relative humidity (RH) from 0% to 100%, with a remarkable capacitance change of 300 pF/%RH. Fast response and recovery times of 60 and 42 s, respectively, have been measured outperforming existing works that utilize metal electrodes. Regarding temperature dependence, the coatings endure conditions ranging from ambient to −25 °C, even in the presence of ice. Furthermore, at 50% RH, the sensors are shown to achieve a maximum sensitivity of 34.2 within a strain range of up to 2%.In conclusion, this work represents a significant advancement in cutting-edge sensor technologies, offering unprecedented capabilities for humidity and strain sensing performance for a wide range of applications.