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Deploy Miniature Sensirion CO2 Sensors for Accurate Indoor Air Quality Monitoring

Sensirion's innovative STC31-C and STCC4 sensors measure thermal conductivity, calculating gas concentration based on that data. They are suitable for both indoor environments and controlled atmospheres. With their high precision and stability, you can always keep CO2 levels under control. (Read time: 4 minutes)

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CO2 sensors by Sensirion: Thermal conductivity-based measurement

Sensirion's STC31-C and STCC4 sensors measure thermal conductivity and use it to determine gas concentration. Being non-selective, the sensors cannot differentiate which specific gas caused the change in thermal conductivity, but the measurement method allows for effective use in indoor and controlled atmospheres where the gas composition is known.

Environmental properties

  • The target gas (CO2) is present in a known mixture of gases (air).
  • Expected air composition: Nitrogen: 78.08% (TC = 25.6), Oxygen: 20.95% (TC = 26.1), Argon: 0.93% (TC = 17.8), Carbon dioxide: 0.04% (TC = 17). TC is expressed in mW/m.K at 25°C. The concentration of other gases in the air is too small to affect thermal conductivity.
  •  Changes in thermal conductivity are solely caused by changes in CO2 concentration.

These conditions are met in both indoor and controlled environments where CO2 is intentionally introduced.

Thermal conductivity is primarily influenced by temperature, with humidity and atmospheric pressure having smaller effects. The Sensirion STC31-C sensor lets you input temperature, relative humidity (RH), and pressure to enhance measurement accuracy, while the STCC4 sensor supports inputs for RH and temperature.

STCC4 Sensor

The STCC4 sensor is well-suited for measuring CO2 concentration in indoor environments, optimized for a range of 400–5,000 ppm (0.04–0.5%), and is expected to be available in Q4 2024.

Typical applications
  • Indoor air quality monitors, smart thermostats, HVAC systems, and more.
Preliminary specifications
  • CO2 measurement range: 400–5,000 ppm
  • Accuracy: ±(100 ppm + 10%) of the measured value
  • Supply voltage: 3.3 V
  • Average supply current: 850 uA, max. supply current: 5 mA
  • Interface: I²C
  • Dimensions (L x W x H): 4 x 3 x 1.2 mm
STCC4
STCC4
Gas Sensors
Thermal Conductivity Sensor Calibrated for Air + CO2 mixture
{_'na objednávku'}
Ord.number: 410169
SENSIRION
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STC31-C Sensor

The STC31-C sensor is suitable for measuring CO2 concentrations ranging from 1% to 100%, commonly found in controlled atmospheres.

Typical applications
  • Perishable Goods Transportation. CO2 is typically maintained between 1–20%.
  • Bioreactors and Incubators. Maintaining constant CO2 levels and humidity for optimal cell cultivation.
  • Supermarkets/Industry. Used in CO2 cooling systems and fire suppression systems.
  • Winemaking/Brewing Industry. Fermentation testing probes, operator safety.
  • Breath Testing: Provides a simple yes/no confirmation if a sample comes from human breath.
  • Breath Analysis: Precise CO2 measurement in breath is possible but requires significant development effort. Sensirion is able to support large-scale projects involving over 6,000 sensors.
STC31-C specifications
  • 4 selectable environment models: 0–40% CO2 in air, 0–100% CO2 in air, 0–40% CO2 in N2, and 0–100% CO2 in N2.
  • Accuracy: ±0.2–2.0% (refer to datasheet for details)
  • Ultra-low power consumption
  • Measurement mode: 3 mA typical at 3.3V
  • Idle mode: 50 µA typical at 3.3V
  • Sleep mode: 1 µA maximum at 3.3V
  • Fast response time (τ63): < 0.5 seconds
  • I²C interface
  • 4 configurable I²C addresses via a resistor between ADDR pin and VDD
  • Backward compatible with STC31
  • 12-QFN package, 3.5 x 3 x 1 mm
STC31-C-R3
STC31-C-R3
Gas Sensors
Thermal Conductivity Sensor Calibrated for Air, N2 + CO2 mixture
in stock 146 pcs
Ord.number: 411243
SENSIRION
1 pcs+
29,00 €
50 pcs+
23,20 €
100 pcs+
22,60 €
250 pcs+
22,40 €
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We’re excited to offer both the STCC4 and STC31-C gas sensors from Sensirion as part of our product range.  The STC31-C sensor is available immediately from our warehouse for your applications. The STCC4 sensor is expected to be available by Q4 2024, as per the manufacturer’s timeline.


Need more information or a sample?

Interested in more details about Sensirion products or need technical assistance with your selection? Have another question or request? Feel free to reach out to us, and we’ll be happy to help.

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