Sono-Extracted Crystalline Nanocellulose Thin Film as a Supporting Material for Fabrication of Highly Sensitive and Stable Flexible Sensors for Thermal Applications

In this study, we presented a durable, nontoxic, lightweight, stable, and highly sensitive flexible thermal sensor fabricated using a crystalline nanocellulose (CNC) thin film as a substrate. The CNCs were extracted from crude sawdust of chir wood by an improvised sonoextraction method, which needs relatively much less chemicals at various steps such as delignification, bleaching, and hydrolysis. The cast CNC thin film had appreciable flexibility with an average thickness of ∼10 μm and an estimated crystallinity index of ∼80.06%. The CNC film shows exceptional thermal stability up to 500 K. A thermal sensor based on the principle of a resistance thermometer was fabricated, which weighed ∼0.13 g. The fabricated thermal sensor on CNC thin film was examined over a period of 4 weeks for stability under varying temperature conditions. Along with high stability, a sensitivity of 0.6%/°C was recorded. The present investigation shows the excellent applicability of the extracted CNCs and their thin films for thermal sensor device fabrication. Additionally, thermal degradation studies using the advanced isoconversional method, Kissinger’s equation, and Cardio Master plot provided further information on thermal stability with kinetics and thermodynamics parameters such as activation energy, pre-exponential factor, and reaction mechanism.