Sensirion preps multi-gas sensor 'nose' for smartphones

November 21, 2013 // By Peter Clarke
Sensirion AG, a vendor of temperature and humidity sensors, has developed a multi-gas sensor that it is planning to sell to smartphone makers.

The sensor platform will allow phones to act as alcohol breathalysers and monitor air quality, amongst other applications, as part of the next stage of smartphone evolution, the company reckons.


Moritz Lechner, co-CEO of Sensirion (Staefa Zurich), said that the company has working examples of multi-gas sensors and plans to ship samples to potential customers in the spring of 2014 with the aim of ramping production in 2015.


Sensirion, founded in 1998 as a spin off from the Swiss Federal Institute of Technology (ETH) in Zurich, has achieved success in multiple sectors through the use of its 'CMOSens' technology, which combines temperature and humidity sensors and the analysis electronics in a single chip.


Lechner said the multi-gas platform would also be based on CMOS process technology using an array of miniature metal-oxide semiconductor (MOS) detector sites. As well as targeting specific gases the multi-site sensor will allow a process of profile matching to indicate the likely presence of other gases and scents.


Conventionally a MOS gas sensor is based on a heated film of a metal oxide such as tin oxide. As the temperature rises different gas molecules are adsorbed on the oxide surface where they change its electrical resistance. With suitably designed and calibrated sensors it is possible to detect numerous different gases at various concentrations including CO, NOX, NH3, CO2, water vapor, ozone and volatile organic compounds (VOC).


Different metal-oxides show a different sensitivity to different gases. Similarly, doping a specific metal-oxide such as tin-oxide with other metal-oxides or trace elements can alter sensitivity. By producing an array of different metal-oxide "pixels" and measuring the resistance of each one against temperature and time it is possible to build up a signature profile for numerous gases. It also means that the sensor can also be "taught" to identify novel gases and scents. Such odors would be introduced to the sensor and the profile noted.