Gas sensors are useful when we want to know something about the presence of chemicals in the air around us. They are used to find leaks, which can increase efficiency in industrial processes and reduce emissions, or to improve the health and comfort of our offices and homes.
However, it is important to select the right gas sensor for specific applications to ensure both cost effectiveness and adequate performance. Engineers need to consider several factors to evaluate the quality of the gas sensor, including sensitivity (detection of very low levels of gas), selectivity (how well it performs when other gases are present), and stability (how reliably it performs over time).
Finding the right sensor also largely depends on the gases being detected and the target application. Once the applications and target gases have been defined, the most suitable type of sensor can be selected for the given application. A wide variety of sensors are used in gas detection applications, including electrochemical, optical, acoustic or chemiresisitive (metal oxide or polymer based) sensors. Metal Oxide (MOx) sensors are a cost effective solution for many applications that have been on the market for more than 50 years. These sensors can be simplified as a thermally isolated substrate, typically ceramic or silicon based, with integrated heater, interdigitated electrodes and a sensing material (MOx). The analog output or resistance measurement from the sensor can then be interpreted to identify the presence of the target gas (leak detection), or to quantify the level of gas present. Selection of the specific material and operating temperature determine the reliability and stability and are developed by the sensor manufacturer to target specific applications.
Another thing to consider when choosing the right sensor is that gases have unique signatures at varying MOx temperatures. For example, hydrogen detection may have an optimal temperature of 240 degrees °C where the gas sensitivity is high, and the response and recovery time, and stability are also very good.
The use of specific catalytic materials, deposition and sintering techniques, and operating conditions will define the commercial success of the MOx sensor technology. For example, detection of trace gases, measured in parts per billion (ppb) may require hotter operating temperatures or different MOx materials with a shorter life expectancy while a sensor with lower requirements could operate for more than five years.
MOx sensors are a great option for designers looking for a solution that provides good utility at a commercially acceptable price. Understanding the problem to be solved with appropriate design parameters yields a positive outcome when addressing air quality and leak detection applications. Additionally, partnering with experts in gas sensing accelerates development time as well as increases the probability of success.
IDT is committed to providing gas sensor solutions for a wide range of applications, including sensor technology in development targeting indoor air quality.
To learn more about IDT’s best-in-class MOx sensors for long term stability and support, visit idt.com/gas.