The paper investigates the possibility or realizing a low-cost gas sensor based on graphene. The gas sensor is realized by means of a microstrip-like circuit where the sensing area is a gap between two copper electrodes, filled by few layer graphene nanoplatelets. Graphene nanoplatelets are here obtained through a solvent-free procedure, from thermal expansion of intercalated graphite, followed by sonication. Then, the graphene contact self-assembles in a bottom-up procedure assisted by an external electrical field. In presence of gas, the graphene sensing area changes its electrical conductivity, so that the gas detection is obtained by simply checking the variation of the terminal resistance of the proposed device. Experimental results show the capability of the realized graphene sensor to detect the presence of acetylene gas even at very low pressure values (few tens of Torr). © 2016 IEEE.