Smoke Detector

Why it matters

The smoke detector uses a small sensor to notice smoke early enough for people to escape, especially while sleeping.

How it works

Common detectors use ionization or photoelectric sensing. One responds to particles changing an electrical current; the other detects how smoke scatters light.

Design notes

• The design challenge is sensitivity without constant false alarms.
• Battery chirps are annoying by design: the device must demand maintenance.
• Placement matters because smoke movement depends on room shape and airflow.

Timeline

1. 1960s: affordable detector designs
2. 1970s: residential adoption grows
3. Today: interconnected and smart detectors