Nanomaterials/Polymer-Integrated Flexible Sensors: A Full-Laser-Processing Approach for Real-Time Analyte Monitoring

In this study, we develop fully laser-made electrochemical “drop sensors,” including all three electrodes as in conventional screen-printed electrodes. Our approach is based on the laser processing of graphene oxide (GO) and silver nanoparticle films on a polyethylene terephthalate (PET) substrate to produce electrically conductive and robust free-form composites. The system contains laser-reduced graphene as working and counter electrodes, while laser-integrated silver serves as the reference electrode. We systematically investigate the structural, electrical, and electrochemical properties of these electrodes, showing that our optimized laser processing allows creating electrodes with a near-record low sheet resistance of 29
$\pm 2 \Omega $
sq
$^{-1}$
. We successfully demonstrated the practical implementation of the sensor for caffeine detection in a 200-
$\mu \text{L}$
drop with a sensitivity of 17
$\pm 3 \mu \text{A}$
mM
$^{-1}$
highlighting its efficiency in a small-volume analysis. Remarkably, this laser processing approach enabled devices that retained their sensing performance even after undergoing 1000 bending cycles. These findings have significant implications for the development of flexible, sensitive, and robust devices in various applications, ranging from healthcare monitoring to environmental sensing, highlighting the transformative potential of laser-based sensor fabrication technology.