The gas sensing industry: look at the 1 percent

Citation

Bogue, R. (2011), "The gas sensing industry: look at the 1 percent", Sensor Review, Vol. 31 No. 1. https://doi.org/10.1108/sr.2011.08731aaa.003

The gas sensing industry: look at the 1 percent

Article Type: Viewpoint From: Sensor Review, Volume 31, Issue 1

Keywords Gases, Sensors, Research and development

Over 99 percent of all measurements made with gas sensors are for oxygen; the sensors are made by a small number of large companies; and the remainder of the market is dominated by just four, well-established techniques.

On the basis of these bare facts, it would be easy to see gas sensing as a rather dull and static business but this is far from the truth and the above statement belies a technologically varied, complex and dynamic sector of the sensor industry. The high percentage of oxygen measurements simply reflects that almost every petrol-driven vehicle uses oxygen (lambda) sensors, produced by the large automotive component manufacturers, to make hundreds of measurements each second to control the engine’s air/fuel ratio. The relatively small number of techniques which enjoy the most widespread use – solid electrolyte (lambda sensors), wet electrolyte (“electrochemical”), catalytic, metal oxide and infra-red absorption – are just the tip of a technological iceberg. There is the “second tier” of techniques which include paramagnetism, photoionisation, flame ionisation, UV absorption and thermal conductivity which are important but find rather fewer uses and finally a third tier, comprising the most specialised techniques such as LIDAR, UV fluorescence, chemiluminescence, photoacoustics, ion mobility, cavity ring-down and laser diode absorption spectroscopy, semiconducting polymers and others.

This technological diversity reflects the diversity of applications which exist across a multitude of industries, each having its own specific requirements. Gas sensors are used in hospitals and battlefields, homes and chemical plant, cars and spacecraft, steel works and greenhouses, the atmosphere and oceans and down mines and up mountains. Over 30 different gases and vapours are routinely sensed but no one technique can measure them all, least of all in the vastly differing concentrations which range from percentages to parts per billion or even trillion. Some pose a threat to health (CO, H₂S, NH₃, Cl₂, etc.), some constitute a risk of fire or explosion (CH₄, C₄H₁₀, H₂, etc.), others govern air quality or threaten the environment (CO₂, NO₂, SO₂, O₃, VOCs, etc.), some have military and security implications (nerve gases, explosives’ vapours, etc.) and there are many more which are highly process- or industry-specific (AsH₃, SF₆, refrigerants, food and perfume aromas, etc.). New markets are constantly emerging due to both new applications, such as vehicle cabin and indoor air quality and homeland security, and those arising in new geographical regions as they industrialise and implement health and safety and environmental legislation.

The numerous applications and technologies have led to a large and fragmented supply sector, comprising hundreds of companies of all sizes, located throughout the world and ranging from very small university spin-offs to major, diversified multinationals. Some just produce bare sensors, some just make instruments and others do both. The UK has traditionally been a strong player: the ubiquitous catalytic sensor (“pellistor”) was developed in 1958 by the Safety in Mines Research Establishment; Sieger, founded a year later, developed its own version, the “Siegistor”; City Technology, founded in 1977, pioneered electrochemical sensors; and in 1990 Capteur started manufacturing technologically advanced metal oxide sensors. Excluding automotive lambda sensors, the global gas sensor market is worth at least £250 million/year, with gas sensor-based instruments and systems exceeding £1.5 billion/year (Hodgkinson et al., 2006), which is sufficient to attract the interest of acquisitive, technology-based concerns. Indeed, recent years have seen much consolidation of gas sensor companies, particularly in the UK. For example, Halma Group, already owning Apollo and Crowcon since the mid-1980s, purchased Telegan which was merged with Crowcon in 2001; City Technology was bought by First Technology in 2000, who then added Capteur, Sensoric and BW Technologies; and Honeywell, who owned Zellweger Analytics, which had previously acquired Sieger in 1979, purchased First Technology in 2006. Despite this trend, new, independent companies continue to emerge in the UK, such as Alphasense, founded in 1997 and now a major supplier of electrochemical and other sensors and more recently Owlstone, in 2003, which is commercialising a unique form of ion mobility spectrometry and Applied Nanodetectors in 2004 which is developing nanomaterial-based gas sensors, to name but three.

Another feature that characterises this industry is the quantity of research being conducted. This is a global endeavour and in addition to a huge academic effort, most gas detection companies invest between 15 and 50 percent of their profits and between 2 and 10 percent of their sales revenues in R&D. While the existing technologies and endless product variants satisfy a multitude of applications, there is a constant search for improvements, such as reducing power consumption, enhancing specificity, increasing operating lifetimes and extending environmental performance. The research effort is investigating the capabilities of all manner of new and emerging technologies and examples include nanomaterials, MEMS, novel lasers and other optical sources, microresonators, gas-responsive biosensors and advanced spectroscopic techniques. Some of these are considered elsewhere in this issue.

So, to appreciate the complexities of the gas sensing, ignore the 99 percent of measurements, look at the remaining 1 percent and you will see a vibrant and technologically diverse industry.

Robert BogueAssociate Editor of Sensor Review