  Biomonitoring wearable sensors based on two-dimensional nanomaterials have
lately elicited keen research interest and potential for a new range of
flexible nanoelectronic devices. Practical nanomaterial-based devices suited
for real-world service, which have first-rate performance while being an
attractive accessory, are still distant. We report a multifunctional flexible
wearable sensor fabricated using an ultra-thin percolative layer of microwave
exfoliated graphene nanosheets on laser-patterned gold circular inter-digitated
electrodes for monitoring vital human physiological parameters. This Graphene
on Laser-patterned Electrodes (GLE) sensor displays an ultra-high strain
resolution of 0.024% and a record gauge factor of 6.3e7 and exceptional
stability and repeatability in its operating range. The sensor was subjected to
biomonitoring experiments like measurement of heart rate, breathing rate, body
temperature, and hydration level, which are vital health parameters, especially
considering the current pandemic scenario. The sensor also served in
applications such as a pedometer, limb movement tracking, and control switch
for human interaction. The innovative laser-etch process used to pattern gold
thin-film electrodes and shapes, with the multifunctional incognizable graphene
layer, provides a technique for integrating multiple sensors in a wearable
fashion accessory. The reported work marks a giant leap from the conventional
banal devices to a highly marketable multifunctional sensor array as a
biomonitoring fashion accessory.
