CDM7160/World leader in gas sensing innovation

Accurate measurement wherever
people are present
Non-Dispersive Infra-Red (NDIR) 
CO2 Sensor Module


Single light source, two detectors 
Employs a single infrared light source and two detectors
High-reliability design prevents sensitivity deterioration

Measurement of absolute values using comparative detection with two detector elements

Conventional CO2 sensor modules employing a single detector element assume a reference value of 400ppm in unoccupied space and use the relative value detection, measuring CO2 concentrations by calculating the difference from the reference value. In actual environments in which occupants are present 24/7, CO2 concentrations never fall to the 400ppm reference value, resulting in measurement errors due to the difference between true CO2 concentration and the reference value.
To solve this problem, the CDM7160 employs two detectors with different optical filters in front of each detector. One detector measures the intensity of infrared light passing through the optical filter, transmitting only the infrared wavelength region absorbed by CO2 (CO2 absorption wavelength). The other detector measures the intensity of infrared light passing through the optical filter, transmitting only the infrared wavelength not absorbed by CO2 (i.e. a reference wavelength), and is thus unaffected by the constant presence of CO2.

Principle of measuring absolute values
Measuring the infrared light intensity
in the two wavelength bands passing
through the optical filters

The amount of infrared light from the light source declines over years of use, as well as from contamination of the optical system. Infrared transmittance at the reference wavelength is constantly measured. Measurement of the absolute value of CO2 concentration is permitted by calculating CO2 concentration from the difference between transmittance at the CO2 absorption wavelength and the reference wavelength.

source of figure:
・NIST Chemistry WebBook
・NIST Standard Reference Database Number 69
(NIST: National Institute of Standards and Technology, U.S. Department of Commerce)

Cost-effective single light source, dual wavelength sensor

NDIR CO2 sensors are broadly classified into three types - Single light source, single wavelength; Dual light source, dual wavelength; and Single light source, dual wavelength.
The single light source, dual wavelength system employed by the CDM7160 measures light intensities at two different wavelengths after separation by two optical filters, thus compensating drift due to accumulated dust and contamination. This ensures long-term stability, minimum maintenance, and high cost-effectiveness.

System Single light source, single wavelength sensor Single light source, dual wavelength sensor
Design Measures a single wavelength from a single light source Measures two wavelengths split from a single light source
Features Reliability deteriorates over time as dust and
contamination adhere to optical component surfaces
High cost-efficiency, with superior long-term stability
Compensates for long-term drift


Digital measured data are output to peripheral devices
via two interfaces, UART or I2C

Measured CO2 concentration data can be output to a PC or external control device via UART (Universal Asynchronous Receiver Transmitter) interface, which is embedded into most of the latest microprocessors.
The CDM7160 also incorporates an I2C (Inter-Integrated Circuit) interface for high-speed communications between the CO2 sensor and peripheral devices that are directly connected within a short distance. The I2C interface is not suitable for communication with remote devices. By connecting the CO2 sensor with an external microprocessor via the UART interface, measured data can be sent to or be received from a variety of control devices and equipment through the microprocessor. By utilizing a microcomputer with communication functions, data from the CO2 sensor can be transmitted wirelessly for remote control operations.


Internal design does not require
a reflector plate, thus extending 
sensor calibration intervals

In NDIR designs employing a reflector plate, any slight change in the angle of the plate due to vibration, shock, or accumulation of contamination in the gas cell can prevent accurate measurement. By employing a simple design without the use of a reflector plate, the effect on sensor accuracy over years of use is minimized, reducing the need to calibrate the sensor. It is expected that the CDM7160 will satisfy the requirement for calibration every five years as specified in the California Building Code.


Superior sensors through simple design


From locations where measurement accuracy in constant 
operation is required (e.g. hospitals, libraries, and public facilities) to indoor 
air control systems which can be combined with Building
Energy Management Systems (BEMS) and Home Energy 
Management Systems (HEMS).

Suitable for a wide range of applications such as ventilation control equipment, air conditioning equipment, and small measuring devices for indoor environmental comfort and energy efficiency. Expected application includes input devices for environmental measurement in IoT and M2M products.

Supply system

Supply of individually calibrated CO2 sensor modules

Supplied as calibrated CO2 sensor modules, and therefore able to be readily incorporated into applied equipment.

For VOC, CO, CO2 A single source for air quality control
gas sensor requirements

Figaro has a wide range of product lines, including semiconductor VOC sensors for detection of low concentrations and battery operable electrochemical CO sensors. Figaro is one of the few gas sensor manufacturers in the world supplying VOC, CO, and CO2 gas sensors.

MOS type Electrochemical type NDIR type
FIGARO Engineering inc
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