A self-powered, wireless-enabled CO2 sensor unit for environment monitoring has been developed by Gas Sensing Solutions (GSS), Sharp and the University of the West of Scotland.

The SmartIR NDIR CO2 gas sensors are said to be based on GSS’ mid-range infrared, solid state LED and photodiode technology.

With this technology, infrared light is discharged from the LED and travels through the CO2 gas. CO2 absorbs between 4.2 and 4.4µ and the amount of light absorbed indicates how much CO2 is present. According to GSS, the IR LEDs are specifically tuned to emit between 4.2 and 4.4µ, making them much more energy efficient than conventional CO2 detectors.

The prototype consists of the Sharp energy harvester, a charge management interface module, the GSS SmartIR CO2 sensor and a low power MCU/wireless module housed in a custom enclosure.

With an energy per measurement requirement of 6mJ, it is suitable for extremely low power and wireless applications.The overall power consumption of the sensor can be adapted to the application as the sensor is only switched on when taking a measurement – of the temperature, humidity or light, for example.

The platform can perform at light levels less than 10lux thanks to its photovoltaic energy harvester optimised for florescent and LED indoor light.

The harvester array is said to be capable of producing more than 20μW/cm2 at 200lux, the 10cm2 array used in the prototype produces 40μA at this light level.

For the prototype, a proprietary wireless interface operating at 868MHz was used. However, the supply module could support low power wireless formats such as LoRA, BLE and Zigbee.