Abstract
In this paper we report on how to increase the selectivity of gas sensors by using fluoropolymer membranes. The mass transport of polar and non-polar gases through a polymer membrane matrix was studied by systematic selection of polymers with different degrees of fluorination, as well as polymers whose monomers have ether groups (-O-) in addition to fluorine groups (-F). For the study, a set of application-relevant gases including H2, CO, CO2, NO2, methane, ethanol, acetone, and acetaldehyde as well as various concentrations of relative humidity were used. These gases have different functional groups and polarities, yet have a similar kinetic diameter and are therefore typically difficult to separate. The concentrations of the gases were chosen according to international indicative limit values (TWA, STEL). To measure the concentration in the feed and permeate, we used tin-dioxide-based metal oxide gas sensors with palladium catalyst (SnO2:Pd), catalytic sensors (also SnO2:Pd-based) and thermal conductivity sensors. This allows a close examination of the interdependence of diffusion and physicochemical operating principle of the sensor. Our goal is to increase the selectivity of gas sensors by using inexpensive fluoropolymer membranes. The measurements showed that through membranes with low polarity, preferably non-polar gases are transported. Furthermore, the degree of crystallization influences the permeability and selectivity of a polymer membrane. Basically the polar polymers showed a higher permeability to water vapor and polar substances than non-polar polymer membranes.
Highlights
The early detection of toxic and flammable gases has very high relevance in many applications and areas in order to protect human life and prevent damages to the environment and infrastructure.To date, many different gas sensors are available for all types of gases and concentrations, adapted and optimized to their specific application
Our goal is to increase the selectivity of gas sensors by using inexpensive fluoropolymer membranes
The aim of our study is to find simple relationships to predict the permeability of gas permeation (GP) membranes towards polar and non-polar gases
Summary
The early detection of toxic and flammable gases has very high relevance in many applications and areas in order to protect human life and prevent damages to the environment and infrastructure.To date, many different gas sensors are available for all types of gases and concentrations, adapted and optimized to their specific application. Comprehensive overviews of the application areas of gas analysis as well as the theoretical background of the analysis methods can be found in [1,2,3]. In many of these applications a reliable chemical sensor with reduced accuracy is sufficient. Such chemical gas sensors are distinguished from mainly optical, sophisticated systems for gas analysis [4] by the following properties: chemical sensors are small, have integrated microelectronics, can be used in mobile applications, have low power consumption and are inexpensive to manufacture by using MEMS technology.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
