Stretchable patterned graphene gas sensor driven by integrated micro-supercapacitor array

We report on the fabrication of a stretchable patterned graphene gas sensor driven by integrated micro-supercapacitor (MSC) array on the same deformable substrate. The integrated MSCs consist of polyaniline-wrapped multi-walled carbon nanotube electrodes and an ionogel electrolyte of poly(ethylene glycol)diacrylate and 1-ethyl-3-methylimidazoliumbis (trifluoromethylsulfonyl) imide. The deformable soft Ecoflex substrate was designed to suppress the applied strain on the gas sensor and MSCs via insertion of stiff platforms of SU-8 underneath and serpentine electrical interconnections of polymer-encapsulated long and narrow Au thin film. The fabricated MSC array demonstrated stable electrochemical performance under a uniaxial strain of 50% and a biaxial strain of 40%, maintaining its initial characteristics even after 1000 cycles of repetitive uniaxial and biaxial stretching. Furthermore, the patterned-graphene sensor detected NO2 gas for longer than 50 min via integration with MSCs using the serpentine interconnections even under uniaxial stretching by 50%. This work suggests fundamental progress towards the development of stretchable environmental sensor system which can be driven by integrated energy storage devices without external long wire connections to power source.