Potentiometric Wearable Sensors with a Laser Engraved Graphene Layer as Transducer

Laser-induced graphene has gained great attention recently for sensing devices. LIGs are generated through the process of irradiating carbon-rich polymers, primarily polyimide, using a laser beam. This procedure induces localized photothermal reactions, resulting in the conversion of SP3 carbon atom hybridization into a three-dimensional graphitic-like structure. This maskless, scalable, simple, reproducible, cost-effective, and fast technique produces high-quality graphene layers with outstanding flexibility, electrical conductivity, and electrocatalytic properties instead of using the conventional time-consuming, expensive, and complicated methods such as wet chemistry, ink-jet printing, and chemical vapor deposition (CVD). In this work, we discuss surface modification and properties of graphene for achieving a stable interfacial potential in contact with a lipophilic sensing membrane, in a potentiometric readout mode. Specifically, surface topography and hydrophilicity of the material impacts the long-term and short-term properties of the wearable sensors. We will show how the engraving conditions impact water layer formation and drift of sensors, and how a highly stable readout can be achieved through surface modification. We use bio-inspired organic receptors to achieve ion specific binding at the electrode surface and generate biomarker specific signal.