Artificially weaved textile-like surface micromachined graphene-polymer flexible bioelectrodes

Official URL: https://dx.doi.org/10.1002/admt.202402032

Dry, flexible, and self-adhesive sensors are critical enablers for wearable, long-term biosignal recording devices. Here, an ultra-thin, flexible textile-like microstructured electrode with self-adhesive abilities is presented for conformal attachment and long-term electrocardiography (ECG) recording. The reported electrode is manufactured using a spin-coatable and electron-beam sensitive formulation of poly (methyl methacrylate) (PMMA) resist, also commonly known as acrylic, which is at the same time a widely-employed material in the textile industry. The textile-like structure of the bioelectrodes with a linewidth of 100 µm and gap size of 100 µm is achieved by patterning PMMA through oxygen plasma and a hard mask layer without requiring complex and expensive e-beam lithography (EBL) processes. Graphene oxide (GO) is introduced to the electrodes as active material followed by a reduction step using eco-friendly pure vitamin C (L-ascorbic acid). The functionality of the reported electrodes is benchmarked against pre-gelled wet Ag/AgCl electrodes, comparing their signal quality and skin-electrode impedance, and achieving a correlation score of 98.84%. Furthermore, it is demonstrated that the electrodes are flexible, water resistant, and can be used multiple times; rendering them suitable for wearable electronics purposes even during intense physical activities both in dry and wet environments.