Posted in | Gas Sensors

Easy and Accurate Gas Detection with the INIR Sensor

The new infrared (INIR) sensor range supplied by SGX Sensortech can detect carbon dioxide and flammable gases easily and effectively. They are integrated with advanced electronics, with a high-performance optical cavity and come with all the required firmware and driver circuitry to create temperature-compensated digital output.

Currently two INIR sensors are available, which are able to sense 5% carbon dioxide and 100% methane, with more to follow soon.

Featuring a minimum circuitry design, the devices can function in challenging environments and create readings quickly and precisely. They can be used in portable as well as fixed instruments.

INIR sensors reacts rapidly to any changes in target gases and give precise and repeatable signals. They are housed in an explosion proof package and feature a rugged shock and vibration proof design for use in critical-to-safety applications.

It is not easy to use infra-red sensors in applications where water is present, whether in the form of steam produced during steel production or water arising from dust suppression systems in mines. Such conditions can create many issues for optical sensors and lead to false alarms.

In contrast, INIR sensors features proprietary firmware and hardware that can easily detect the presence of humidity and reduce the sensor’s response considerably. This means they are suitable for use in environments where the atmosphere constantly varies from wet to dry and vice versa.

INIR sensors are also integrated with reliable and powerful microcontrollers (MCU), which are driven by a 24 bit analog to digital converter (ADC) and an ARM7TDMI core. This MCU is capable of performing all the preferred operations on the raw sensor output, offering a 14-bit digital output.

Through a universal asynchronous receive/transmit (UART) interface, INIR sensors can be easily calibrated and configured. The sensors are also provided with an analog output option with an integrated ADC.

INIR sensors also features the required electronics and integrated software to work from a low voltage DC power supply.

Raw signals processed by the sensor are produced as a linear, temperature-compensated signal that is proportional to the applied gas concentration. The output signal comes in both analogue and digital forms.

With the aid of INIR gas sensors, users can easily integrate an infrared sensor into their gas detection device, thereby significantly reducing the development time and the expertise needed during the design and implementation stages. A gas sensor can be used to calibrate the sesnors to facilitate installation without the added necessity for recalibration.

The INIR Sensor Range from SGX Sensortech

Two versions of the INIR are currently available with more to follow;

  • The INIR-CD5% - 5% range Carbon Dioxide
  • The INIR-ME100% - 100% range methane

Principle of Operation

The central technology of INIR sensors feature a popular NDIR gas sensing method, combined with a high- performance printed circuit board and a powerful and reliable ARM7 MCU.

INIR gas sensors are the new, enhanced digital version of the 7-pin single gas IR12GM_1 (methane) and IR11GM_1 (carbon dioxide) gas sensors. These sensors include a supported lamp to provide extra shock protection.

The configuration unit can be used to set up, calibrate, and assess the INIR sensor through the USB interface with user-friendly PC software. INIR sensors can also be controlled through UART to communicate with their external microprocessor. They include full fault diagnostics that are transmitted through the digital string together with the sensor‘s temperature output and the linearized concentration in parts per million.

Key Features

  • High resolution up to 35 ppm
  • Detectivity level down to 100 ppm
  • Triple range gas sensor with automatic switchover between ranges
  • Analog and digital concentration output
  • Full faults diagnostics and error generation
  • Active and reference signals monitored digitally transmitted values through UART
  • Internal temperature digitally sent through UART
  • Sophisticated ESD ±30 kV (IEC 61000-4-2) protection
  • Automatic over current protection function
  • Automatic thermal shutdown function
  • Cyclic redundancy check
  • Low power consumption < 32mA (average)
  • Factory calibrated for carbon dioxide and methane, or for other gases, if required
  • Three different modes of operation
  • 14-bit DAC output
  • 24-bit ADC
  • Can be easily implemented into sensors network
  • Can be used in hazardous entrainments
  • Sensor has been certified for use in explosive atmospheres
  • Evaluation kit available including PC software to enable simple testing and production calibration functions


  • Indoor air quality
  • Automation and control
  • Mining
  • Industrial health and safety

Technical Specifications and Maximum Ratings

Power Supply Min Typical Max
Supply Voltage (with Tolerances) 3.2 VDC (+5%) 3.3 VDC 5.0 VDC (+/- 5%)
Average Current Consumption 30mA 32mA 35 mA*
*Inrush Current can be up to 65mA
Logic Outputs Level LOW Voltage Level(VOL) : 0.6V Maximum
HIGH Voltage Level(VOH): 2.0V Minimum
1.6mA source current maximum
Logic Inputs Level LOW Voltage Level(VINL): 0.4V Maximum
HIGH Voltage Level(VINH): 2.0V Minimum
Operating Humidity 0% 50% 99%
Storage Humidity 0% 50% 90%
(>100% Humidity)
Sensor’s Detectivity, Stability & Linearity would be affected but algorithms are implemented to minimize the effect.
Operating Temp. -40 °C +20 °C +75 °C
Storage Temp. -20 °C +20 °C +55 °C
Temp. Cycle Limits 0.25 °C/min 0.75 °C/min 1.25 °C/min
Operating Pressure 80kPa - 120kPa
Storage Pressure 80kPa - 120kPa
ADC Resolution - 24-Bit -
DAC Resolution 14-Bit at 0.0-2.5 Volts DC Max
Scalable according to Gas Conc. Operating Range
Imax= 0.5mA on 5K Resistive Load
Diameter (D) 19.9mm 20mm 20.1mm
Height (H) 16.50mm 16.60mm 16.70mm
Pins Height (pH) 4.0mm 4.8mm 5.6mm
Body Material Stainless Steel
Weight (gr) 25 gr. 29 gr. 33 gr.
Gas Sensor Sockets
S1 6-Pin , Polygon Topology

Other Equipment by this Supplier