Indoor air quality sensor Designers of indoor and vehicle in-cabin air quality monitoring systems can use the 110-801 from SPEC Sensors. The 110-801 is a screen-printed amperometric gas sensor that can detect a broad array of gases associated with poor air quality, including alcohols,
Figure 7: Simplified potentiostat circuit used to implement gas detection using an amperometric sensor. (Image source: Spec Sensors)
ammonia, carbon monoxide, various odorous gases, and
sulfides. The response of these sensors is linearly proportional to the volumetric fraction of the gas being measured, which simplifies system integration (Figure 6). Other features of this 20 x 20 x 3 mm sensor include: ■ Parts per million (ppm) sensitivity ■ Less than ten microwatts (μW) sensor power ■ -10°C to +40°C operating temperature range (0°C to +40°C continuous operation) ■ Robust and stable operation in the presence of a wide range of contaminants
output from the sensor to a voltage signal. At the same time, op amp U1 supplies current to the counter
Amperometric gas sensor integration A potentiostat circuit controls the working electrode’s potential in an amperometric gas sensor and converts the electrode current to an output voltage (Figure 7). The voltage at pin 2 of the operational amplifier (op amp) U1 sets the reference electrode voltage, and the working electrode’s potential is set by pin 6 of op amp U2. Op amp U2 also converts the current
electrode that is equal to the working electrode current.
Summary As shown, designers have a range of air quality sensor technologies to choose from when designing environmental monitoring systems. OPCs can be used to monitor for potentially dangerous particulate levels indoors and outdoors. CAN- based, multi-sensor systems can monitor for first stage venting in EV and BESS battery packs and help to prevent thermal runaway and possible fires or explosions. Low-power, screen-printed amperometric gas sensors can be used to detect a broad array of gases that cause poor air quality.
Figure 6: This screen-printed amperometric gas sensor can measure the presence of a variety of gases. (Image Source: Spec Sensors)
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