▎ 摘　　要

NOVELTY - The method involves forming a ring oscillator (240) on a semiconductor substrate, where the ring oscillator comprises an AND gate (g1), an odd number of inverters (v1-v4) and a carbon device, and each carbon device is connected in series between the inverters. A control ring oscillator is formed on the semiconductor substrate. The control ring oscillator is protected from an environment, where the carbon device comprises carbon nanotubes or graphene, and the carbon device comprises a FET in which a channel of the FET comprises carbon. USE - Method for forming a carbon based environmental sensor. ADVANTAGE - The method enables operating as a voltage controlled oscillator, so that the voltage controlled oscillator is controlled by controlling gate voltage. The method enables changing conductance of the graphene or carbon nanotubes device, thus changing ring oscillator frequency and producing a convenient electrical signal when the analyte is present. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following: (1) a structure for forming a carbon based environmental sensor (2) a method for sensing an analyte in an environment. DESCRIPTION OF DRAWING(S) - The drawing shows a circuit diagram of a sensor. AND gate (g1) Resistors (r1-rn) Inverters (v1-v4) Sensor (200) Ring oscillator (240)