Battery-powered carbon dioxide sensor

Louise Smyth

Gas Sensing Solutions (GSS) has developed a carbon dioxide sensor with an optimised low power infrared LED system for high speed battery operation, writes Nick Flaherty.

The SprintIR6S sensor can take up to 20 readings per second, with a six times faster response rate than the current sensor as it can use a smaller sample volume of only 2ml.

The SprintIR6S can measure CO2 concentrations right up to 100%, providing a cost-effective solution for high concentration monitoring that previously needed very expensive detectors.

The fast response is particularly relevant in industrial applications to monitor that the correct, high levels of CO2 are being used.

"In many industrial applications, it is often vital to monitor CO2 levels to check that an elevated level of CO2 is being maintained at the right concentration for the process or product, " said Alan Henderson, founder of GSS. "In this respect, the SprintIR6S provides almost instant measurements - more than 20 readings in a heartbeat."

The sensor is 23.8mm in diameter and 24mm tall and operates at between 3.25 and 5.5V with a power consumption of only 35mW.

This is achieved by detecting how much light is absorbed by CO2 molecules as light passes through the sample gases - called Non-Dispersive InfraRed (NDIR) absorption.

CO2 absorbs between 4.2 and 4.4 microns and the amount of light absorbed indicates how much CO2 is present.

GSS developed the world's first commercial, mid-range IR LEDs that are specifically tuned to emit between 4.2 and 4.4 microns to measure the absorption, making the sensor highly energy efficient.

"Low CO2 concentration sensor solutions are also particularly important to monitor for any leaks in these industrial settings," said Henderson. "For this, we have a range of ambient air CO2 monitors that work in the 0 to 1% concentration range that are so low power that they can run for 10 years on a single battery.  Increases in CO2 levels can rapidly have a negative effect on people, with alertness being increasingly compromised.

“Our sensors provide a vital early warning.  400 parts per million (ppm) is the normal level of CO2, and effects start from 1,000 ppm with drowsiness and yawning, rising to dizziness, unconsciousness and death.

“This is very much a Health and Safety issue to prevent costly accidents and health problems - especially as CO2 is undetectable to humans as it has no smell or colour, which is also why CO2 levels are increasingly being recognised with legislation in offices, schools and homes," he said.