Fully Written Flexible Potentiometric Sensor Using Two-Dimensional Nanomaterial-Based Conductive Ink

The emerging demand for flexible, portable, easily accessible, and cost-effective electronic fabrication has motivated the development of novel techniques to manufacture electronic components and devices. Inspired by daily handwriting, an all-written potentiometric sensor was developed by using a Chinese brush pen-based writing technique. A writing ink made from graphene nanosheet (GN) as a conductive component, Triton X-100 as a stabilizer, and xanthan gum as a binder, was used to obtain flexible electrode substrate. Results demonstrate the GN ink-based writing electrode (GN-WE) possesses good conductivity, fast electron-transfer kinetics, considerable stability, and favorable flexibility. By further writing cadmium ion selective membrane (Cd2+-ISM) and photopolymerized reference membrane (RM) on the surface of GN-WE, an all-solid-state potentiometric sensor for cadmium ion was constructed. A large bulk capacitance (41.67 mu F) and excellent potential stability (drift of 0.156 mV h(-1)) were achieved at the developed all-written potentiometric sensor, which is much superior to the solid-contact potentiometric sensor using GCE as electrode substrate. Furthermore, real sample analysis reveals that our GN ink-based potentiometric sensor could be used as a reliable and stable sensor for cadmium ion detection in food and in the environment.