▎ 摘　　要

NOVELTY - Ink comprises water, polyvinylpyrrolidone (PVP), or graphene. USE - The ink is useful for fabricating a sensor electrode (claimed). DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) a sensor electrode comprising PVP and graphene; (2) fabricating a functionalized graphene material comprising treating a graphene material with sulfonic acid and/or thiourea and growing metal containing nanostructures on the surface of the treated graphene material; (3) a sensor comprising a sensor electrode comprising graphene material and controller for providing a drive signal to the sensor electrode in order to sense species adhered to the sensor electrode, where the controller is further configured to apply a cleaning voltage to the sensor electrode, the cleaning voltage having a frequency of 100 Hz to 100 KHz and a magnitude of 1-60V, optionally 1-20V, to induce heating of the sensor electrode which removes at least one specie adhered to the sensor electrode; and (4) a sensor system comprising a graphene sensor and at least one other sensor having a higher power consumption than the graphene sensor in sensing operation, where the system is configured such when the graphene sensor senses a target species, or a threshold level of a target, than it sends a single to the higher power sensor to wake up the higher power sensor from a dormant state to take a sensor measurement of the same or a different target species.