Nanomaterial-embedded gas sensors were fabricated on a 4-in. Si wafer counting 200 units. Carbon nanotubes (CNTs) and tin oxide (SnO) nanoparticles were prepared as hosts to detect NO(2) gas molecules at room temperature. Ink-jet approach was applied to deposit nanomaterials on a Si wafer. Metal deposition above the nanomaterials formed the metal-sitting structure providing spontaneous passivation. The performance of the CNT sensor and SnO sensor showed distinctive responses to NO(2) gas depending on the type of semiconductor. The sensor is highly sensitive, to detect a 10 ppb level of NO(2). It offers massive production of nanomaterial gas sensor units, and the performance is discussed. (C) 2009 Elsevier B. V. All rights reserved.