Wearable skin integrated flexible PVA‐nickel nanocomposite patch for temperature sensor

Abstract

AbstractThe study focuses on developing a noninvasive, flexible polyvinyl alcohol (PVA)‐nickel (Ni) nanocomposite thin film as a passive skin‐integrated patch sensor for wearable temperature monitoring, marking a significant advancement in the field of wearable sensors. This flexible PVA‐Ni nanocomposite thin film serves as a temperature‐sensitive material, offering several advantages over commercially available active‐type sensors. Field emission scanning electron microscopy (FE‐SEM) images show that Ni nanoparticles (NPs) are broadly dispersed throughout the PVA matrix, indicating the effectiveness of the conductive patch in detecting temperature variations. A PVA‐Ni nanocomposite patch with a thickness of 0.08 mm demonstrated superior flexibility, breathability, and lower tearing strength compared to a pure PVA patch. The film also exhibited excellent repeatability in bending tests, maintaining performance after 120 bending and unloading cycles, suggesting its durability for long‐term use as a wearable sensor. Furthermore, the fabricated sensors function as thermistors, with conductivity increasing linearly with temperature. The performance of these temperature sensors was compared, revealing a highest temperature coefficient of resistance (TCR) and thermal index of −1.08%/°C and 1271 K, respectively. The sensors showed high temperature sensitivity between room temperature and 50°C, outperforming typical commercial platinum temperature sensors. The stability and response time of the PVA‐Ni nanocomposite film were evaluated by adhering the patch to a human wrist and capturing thermal images using a FLIR thermal imaging camera. The observed maximum temperature difference of approximately 1.9–2.1°C highlights the patch's sensitivity in detecting temperature changes. Additionally, the antimicrobial properties of the conductive film were tested to assess its biocompatibility, confirming its potential for applications in energy storage, thermal management, and early breast cancer detection.