Miniature gas sensors for mobiles

July 29, 2014 // By Peter Clarke
Cambridge CMOS Sensors Ltd (Cambridge, England) has announced the CCS800 family of miniature gas sensors for use detecting alcohol (ethanol), hazardous gases such as carbon monoxide and volatile organic compounds.

The company claims that its patented micro-hotplate technology and a compact 2.0mm by 3.0mm by 1.0mm package developed with the ASE group enables gas sensors to be used within smartphones, tablet computers and wearable devices. Side benefits of the small sized gas sensor include lower power consumption than competitors' sensors and shorter stabilisation and response times.

The sensors employ high-temperature tungsten MOSFET heaters embedded in a silicon-on-insulator (SOI) membrane. These effectively form a micro-hotplate that heats the sensing material, allowing it to react with gas molecules. The MOSFETs can be fabricated in a commercial SOI-CMOS process and therefore can be fully integrated with the associated drive/detection circuitry.

The micro-hotplates are suspended in a high reliability membrane and act as heater elements for a metal oxide (MOX) based sensing material. The material resistance will change due to reactions to selected gases and concentrations at temperatures typically between 200 and 400 degrees C.

Traditionally, MOX gas sensors tend to be non-specific and react to a multitude of gases and baseline and sensitivity vary from sensor to sensor and drift over time.

The CCS800 product family is available in three variants – 801, 802, 803 – tuned for air quality monitor, carbon monoxide and ethanol, respectively. All three are sampling and the CCS_EVK02 is an evaluation kit for the family.

"Global emergence of sophisticated electronics geared towards improving lifestyle and efficiency is fuelling the sensor market, making it one of the fastest growing areas of innovation within the semiconductor industry," commented Fuyu Shih, vice president of ASE Europe, in a statement issued by CCS. "Cambridge CMOS Sensors is an industry leader in sensor technology for monitoring air quality, toxic gas detection and breath analysis through its unique micro-hotplate technology."

Cambridge CMOS Sensors was formed in 2009 as spin-out from the University of Cambridge's Department of Engineering and licensed technology from the University of Warwick.