The present invention relates to a device for rapid detection of salmonella bacteria, a method of fabricating and a method of operating thereof. The biosensor device is an aptasensor comprising a thiolated dna aptamer, wherein the thiolated dna aptamer is deployed onto an electrode having an active electrode area formed by a predefined photolitographic process via a carbon nanotube drop-casted thereon. The biosensor has a low detection limit of analyte and has the ability to measure a wide range of analyte concentrations.