Graphene electronic tattoos 2.0 with enhanced performance, breathability and robustness

Graphene electronic tattoos (GETs) have recently emerged as unique tools for personalized healthcare. The monolayer GETs have been used to monitor human electrophysiological signals, including brain, heart, and muscle activities, skin temperature, and hydration level. However, a few drawbacks of the earlier GETs hindered their perception by clinical and biomedical experts: they were not permeable to sweat, and the tattoo performance varied greatly. In this work, we introduce GETs 2.0: skin-wearable tattoo sensors with superior electrical properties, permeability to sweat, and robustness. We report a categorical analysis of tattoos of different layer constitutions. Stacking graphene monolayers within a single tattoo drastically enhances electronic properties. Prior monolayer GETs were susceptible to growth- or transfer-related discrepancies, resulting in highly scattered electrical properties. GETs 2.0 with graphene nanosheets/nanoscrolls (GNS) or multilayer (2L and 3L) graphene exhibit 3.5-fold decreased sheet resistance, 2.5-fold lower skin impedance, and 5-fold reduced standard deviations. Introducing microholes enables healthy sweat evaporation without substantial decrease in electrical properties and allows biplanar contact. Finally, multilayer GETs 2.0 function as efficient skin-wearable electronic heaters, exhibiting heating efficiency of ~6 mW/°C.

Dmitry Kireev, Jameson Kampf, Alena Hall, Deji Akinwande