3.4 - Sensitive and Fast Gas Sensor for Wide Variety of Applications Based on Novel Differential Infrared Photoacoustic Principle

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings IRS² 2011
I3 - Gas Analysis
I. Kauppinen, A. Branders, J. Uotila - Gasera Ltd., Turku (Finland), J. Kauppinen, T. Kuusela - University of Turku (Finland)
71 - 75


With the increase in the emission of gases from the industries and vehicles, there is a strongly growing need of a solution to monitor the emissions in order to have a cleaner and a greener atmosphere. Furthermore, a fast and sensitive gas sensor with compact size is needed in several applications such as greenhouse gas flux measurements, breath measurements in medical diagnostics, tail pipe measurements in engine development, leak detection and homeland security. There exist a lot of gas measurement solutions, but they are not sensitive, fast, compact and cost efficient enough for the demanding applications.

The proposed solution is a versatile and miniaturized gas sensor sub-system that has the capability to detect the greenhouse gases along with explosive gases, medical markers and chemical agents with orders of magnitude better sensitivity than prior optical measurement methods at the same package volume. The sensor sub-system consists of a differential photoacoustic gas detector, low volume gas cell, reference cell and a light source module. High sensitivity and wide dynamic range in the photoacoustic detector scheme is obtained by the use of patented silicon MEMS cantilever sensor coupled with an optical interferometric readout system. Versatility and scalability to different applications is done by filling the photoacoustic detector module with a high concentration of the target gas, which is different for each application. This also provides the selectivity of the detector at the same time. The light source is selected according to the sensitivity requirement and optimal
wavelength region. The source can range from a broad band black body radiator to a quantum cascade laser. A miniaturized solution for methane leak detection in a 5 cm3 packaging volume is developed using an infrared light-emitting diode with a target of below ppm detection limit in one second. In a realization for greenhouse gas flux measurements the required response time is 0.1 seconds for the sensor with ppb level of detection. This is achieved using a tunable diode laser source.