Electronics
Your air quality monitor cannot smell anything. It watches oxygen cling to a grain of tin oxide
29 Aug 2026 · 12 min read
The gas sensor in an LPG alarm or a ₹2,000 indoor air monitor is a heated speck of metal oxide whose electrical resistance changes when a gas burns off the oxygen stuck to its surface. Understanding that one sentence explains why the readings drift, why humidity confuses them, and why the 'CO₂' number is usually not a measurement at all.
Read more →
