Amperometric Oxygen Sensors as basis for OEM Gas Sensor Modules
Amperometric zirconia oxygen sensors are widely used in industrial applications where accurate oxygen measurement is critical, such as in power plants, chemical plants, and food processing. They are also used in automotive applications to monitor the oxygen concentration in engine exhaust gases. These sensors are highly reliable, with a long operating life and minimal maintenance requirements, making them a popular choice in many industries.
The amperometric oxygen gas sensor modules produced by Angst+Pfister Sensors and Power (APSP) guarantees stable output current over the whole lifetime span of the sensor with an expected lifetime of 10 years. They are known for their high accuracy, stability, and sensitivity to low oxygen concentrations along with fast response time and low cross-sensitivity.
The FCX-U series of zirconia oxygen sensors has 4 types, each with a fixed measurement range: 0-1000 ppmO2 [FCX-ULL], 0-5 Vol%O2 [FCX-UL], 0-25 Vol%O2 [FCX-UC] and 0-95 Vol%O2 [FCX UWC]. All types are heated to 450°C by resistive heating and the output current is controlled by the precise temperature of the sensor element and the sensor voltage across the sensor element. Because of the high temperature of the small ceramic sensor element, the output current from the sensor is almost independent of the gas temperature between 10°C and 50°C. Furthermore, the FCX-U sensors can be used up to 325°C by careful design of the sensor head (cable and package).
The FCX-U series of zirconia oxygen sensors measure the partial pressure of oxygen independent of the static pressure, because the current from the sensor is limited by diffusion and because the whole sensor element is subject to the total, static pressure. The output current from e.g. 0-25 Vol%O2 oxygen sensor (FCX-UC) remain stable over 30.000 hours operation with a maximum drift per year and in air of < 1% relative/year. When reaching end of-life (EOL), the output drift is accelerated to > 10% relative/month. The sensor element is packed in a ceramic wool, which is an apparent advantage, when it comes to gases with high moisture content and/or particles.
Apart from zirconia based amperometric oxygen sensors, APSP also offers diverse portfolio of liquid-, gel- or polymer-based weak alkaline electrolyte based electrochemical oxygen gas sensors. The general working principle of electrochemical oxygen gas sensors is based on the reduction of oxygen on the sensing electrode (Cathode), followed by subsequent oxidation on the second electrode (Anode). Electrochemical gas sensors due to the their stable output current, robustness against silicone and high cost-performance ratio are becoming more and more popular for different applications, ranging from hand-held gas safety devices to complex additive manufacturing processing chambers.
The PO2ES series of oxygen gas sensors by APSP are lead free and have a weak alkaline, liquid electrolyte in a classical 3-eletrode configuration, which makes them very little or non cross sensitive to other gases. The PO2ES oxygen gas sensors can be operated up to 100% r.h. humidity and only has very small output responses to 100 Vol% gases or gas mixtures of carbon dioxide, carbon monoxide, hydrogen, and hydrocarbons. This makes them very well suited for applications such as general gas safety (ATEX) & gas quality during generation, storage, transport, and pumping (biogas, natural gas, propane gas and hydrogen gas). The PO2ES oxygen sensors can also be operated in a dry environment over a long period of time, for instance when using dry nitrogen or argon to lower the oxygen concentration in a closed environment.
The ES1 series of sensors (20+ different gases) from APSP has the electrolyte immobilized in a polymer and printed with a paste on a ceramic substrate. The ES1-O2 0-25 Vol%O2 oxygen sensor has a weak electrolyte immobilized in a thick film printed 3-electrode configuration. A capillary tube provides the interface to the gas sample. The sensor has no orientation effect and has a very small foot-print [11.5mm x 11.5mm] which makes it one of the only oxygen sensor well suited for hand-held analyzers and for integration into applications with limited head space volume. The output from the ES1-O2 oxygen sensor remain stable for wide over 25.000 hours of operation with a maximum drift per year and in air of < 2-5% relative/year. When reaching end-of-life (EOL), the output drift is accelerated to > 10% relative/month.
