A dust sensor is a device used to sense dust concentration in the air, based on the principle of light scattering. When light hits dust particles, scattering occurs; the intensity of the scattered light depends on factors like particle size, shape, and refractive index. The dust sensor calculates the concentration of dust in the air by measuring this intensity.

Therefore, a dust sensor can only detect dust in the air and cannot directly detect solid dust. Solid dust must be converted into airborne dust through certain means before it can be detected by the dust sensor.

Common conversion methods include:

● Vacuum cleaners: A vacuum can suck solid dust into the air, which is then detected by the dust sensor.

● Air purifiers: Air purifiers can adsorb dust particles from the air onto a filter, which can then be monitored by a dust sensor.

● Vibration: Vibrating solid dust causes it to become suspended in the air, allowing the dust sensor to detect it.

For example, robot vacuums typically use optical dust sensors to detect dust on the floor. The robot emits light during operation; if the light is scattered by dust particles on the ground, it indicates the presence of dust.

In air purifiers, laser dust sensors are commonly used. The purifier emits a laser during operation; if the laser is scattered by airborne particles, it indicates dust is present in the air.

In short, dust sensors cannot directly detect solid dust; it must be converted into an airborne state through certain methods to be detected by the dust sensor.