title: Sensitive gas analysis system on a microchip and application for on-site monitoring of NH3 in a clean room.
abstract: A portable, highly sensitive, and continuous ammonia gas monitoring system was developed with a microfluidic chip. The system consists of a main unit, a gas pumping unit, and a computer which serves as an operation console. The size of the system is 45 cm width × 30 cm depth × 30 cm height, and the portable system was realized. A highly efficient and stable extraction method was developed by utilizing an annular gas/liquid laminar flow. In addition, a stable gas/liquid separation method with a PTFE membrane was developed by arranging a fluidic network in three dimensions to achieve almost zero dead volume at the gas/liquid extraction part. The extraction rate was almost 100% with a liquid flow rate of 3.5 μL/min and a gas flow rate of 100 mL/min (contact time of ~15 ms), and the concentration factor was 200 times by calculating the NH(3) concentration (w/w unit) in the gas and liquid phases. Stable phase separation and detection was sustained for more than 3 weeks in an automated operation, which was sufficient for the monitoring application. The lower limit of detection calculated based on a signal-to-noise ratio of 3 was 84 ppt, which showed good detectability for NH(3) analysis. We believe that our system is a very powerful tool for gas analysis due to the advantages of portable size, high sensitivity, and continuous monitoring, and it is particularly useful in the semiconductor field.
authors: Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.
authors: Shinichiro
authors: S
authors: Hiki
authors: Kazuma
authors: K
authors: Mawatari
authors: Arata
authors: A
authors: Aota
authors: Maki
authors: M
authors: Saito
authors: Takehiko
authors: T
authors: Kitamori