Photonic Annealing of Inkjet Printed Graphene for Stretchable Wearable Healthcare Monitoring Devices

Inkjet-printing of graphene (iGr) onto flexible and stretchable electronics has significant potential for environmental sensing and healthcare monitoring applications. However, conventional thermal annealing techniques often require high temperatures that are incompatible with polymeric and fabric substrates. In this work, an in situ photonic annealing protocol with a compact intense pulsed light (IPL) system is developed to achieve conductive iGr films on flexible temperature sensitive substrates. Raman spectroscopy confirms enhanced iGr structural ordering and the decomposition of ink residues, leading to a sheet resistance of ≈430 Ω sq⁻¹. The fabricated films exhibit stable electrical properties under mechanical deformation, maintaining performance under up to 30% elongation, with a temperature sensitivity reaching ≈0.096%°C⁻¹, comparable with that of commercial platinum-based sensor Pt100. Furthermore, the IPL-processed iGr films demonstrate acetone vapor sensing at physiologically-relevant concentrations down to 0.2 ppm, highlighting their potential for healthcare sensing and monitoring. The results establish IPL as a rapid, scalable post-processing technique for iGr, enabling its application in the next-generation wearable and stretchable electronics.