Sensirion SGP41
Also known as: SGP41 · SGP40 · Air quality
The honest VOC sensor: Sensirion's gas-index algorithm turns raw resistance into a stable 1–500 'how weird is my air right now' index that's actually automatable — cooking, solvents and showers show up unmistakably.
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At a glance
⚑ flag an error| Measures | voc, nox |
|---|---|
| Accuracy | VOC + NOx INDEX (1–500, relative) — not ppb, by design |
| Interface | I2C @ 0x59 |
| Supply | 3.3 V |
| Battery-viable | No (continuous draw) |
| ESPHome | Native ESPHome component — sgp4x |
| Typical price | $4-8 (street, varies) |
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Which one do I buy?
SGP40 = VOC only; SGP41 adds NOx. vs ENS160: the Sensirion algorithm is better behaved. vs SGP30: deprecated — don't buy for new builds.
Clone check
Good for
Gotchas to know
- It's an index, not a concentration: 100 = your normal baseline, not a lab measurement. Users expecting ppb are perpetually confused.
- Feed it temperature/humidity compensation (an SHT4x on the same bus) or the index degrades.
- The heater draws a few mA continuously — not a deep-sleep part.
Wiring it up
It's I2C, so it shares two pins with every other I2C sensor you own — chain your climate/light/CO2 stack on one bus and mind the address clashes (this one lives at 0x59). Any ESP32 dev board works.