A gas sensor in every smartphone – but with an 8051?

January 16, 2016 | 18:54
Image source: Cambridge CMOS Sensors
Image source: Cambridge CMOS Sensors
Smartphones may soon contain gas sensors. The tiny 1 millimeter square MEMS-CMOS die produced by Cambridge CMOS Sensors Ltd. (U.K.) is small and cheap enough to go widescale, and may beat Apple for the first time in new types of MEMS gas sensors in smartphones. The demand should be enormous, starting in smog-laden Chinese cities.

The new all-digital CCS811 sensor can be configured to sense volatile organic compounds (VOC) such as carbon monoxide, formaldehyde, or even alcohol. Alternatively it can be configured with different top-metal oxides or filters to detect only CO2, only ethanol, or nearly any other noxious gas. It can also be configured to measure the outside air quality, including nitrogen dioxide [NO2].

{Image source: Cambridge CMOS Sensors}
The newest version uses a Silicon Labs 8051 microcontroller housed in the same package as the MEMS-CMOS die. The sensor and the micro together measure the resistance between gold electrodes and buffer its changes in real time. Reportedly, five-year battery lifetimes are easy to attain with small lithium batteries. The package size today is 2.7-by-4.0-by-0.6 millimeters to hold the CCS81, 8051 and I2S interface. The lot uses under 1.2 milliwatts when active and under 6 microwatts in idle mode.


Huh, 8051?? That’s right, no CortexXYZ, it’s 8051 and MEMS: surely a case of Back to the Future.
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