 This paper proposes a new method called Low Frequency Noise Spectroscopy, LFNS, which uses a single FET type gas sensor to detect specific gases. The LFN of the sensor is modeled as a result of charge fluctuations in both the sensing material and the FET channel. This model allows for selective detection of target gases based on their unique frequency characteristics. Additionally, a 3D vertical manned flash array is used to improve the area and power efficiency of the system. The proposed system offers a more efficient and effective way to detect specific gases compared to previous methods. This article was authored by Won Jun Shin, Jae Hyun Kim, Gyu Hyun Young, and others.