Air purifier air quality sensor

When it comes to air purifiers, there are many online guides available for purchasing and using them. However, one often overlooked component of an air purifier is the air quality sensor. In this article, we will delve into the function of the air quality sensor in an air purifier.

Introduction to the Working Principle of an Air Purifier Air Quality Sensor

Electrochemical sensors analyze the concentration, properties, components and other information of the substance to be measured by detecting the current, voltage and other signals generated in the electrochemical reaction. There are three commonly used electrochemical sensors, namely electrolytic cells, electrochemical biosensors and nanocapillary electrochemical sensors.

Electrolytic cell sensors are mostly used to measure parameters such as ion concentration and pH value. Taking the pH value as an example, when the pH value changes, the concentration of hydrogen ions or hydroxide ions in the electrolytic cell changes, thereby generating signals such as current and voltage. The pH value can be obtained by calculating the magnitude of these signals, thereby improving the environment. Take measurements

Electrochemical biosensors realize the detection of certain biological substances by connecting enzymes, antibodies, etc. in organisms to the electrode surface. For example, the concentration of glucose can be measured by attaching glucose oxidase to the electrode surface

Nanocapillary electrochemical sensors are often used to detect trace substances, such as heavy metals and organic substances. The sensor measures the concentration of the substance to be measured by connecting the nanocapillary to the electrode and using parameters such as electrode potential and current.

Comparison of the Two Mainstream Air Purifier Air Quality Sensors

Although both infrared sensors and Laser Dust Sensors are mainstream products, their structures differ significantly. The internal structure and circuit design of infrared sensors are relatively simple, while laser sensors are more complex.

The difference in design leads to differences in measurement accuracy. Infrared sensors utilize infrared light-emitting diodes as the light source, while laser sensors use more stable laser diodes.

To ensure the flow of air through the intersection area between the light source and the receiver, the infrared sensor uses resistance heating to generate hot air that drives the surrounding gas flow. On the other hand, laser sensors have a built-in fan to facilitate air flow.

In terms of signal output, the phototransistor inside the infrared sensor can only generate a pulse width modulated signal (PWM signal). This signal alone cannot directly display the particulate matter concentration in the air and requires further calculations to obtain the particle concentration range. In contrast, the photoelectric detector in laser sensors produces a current signal through the photoelectric effect. After amplification by the circuit, the particle concentration value can be obtained. The signal is typically outputted through the serial port.


This explains why some purifiers can only indicate air quality through different colored lights, while others can display specific air quality indexes in digital form.

Additionally, the infrared sensor’s resistance heating method for driving airflow samples a smaller number of particles, resulting in slightly lower testing accuracy. Conversely, the laser sensor, driven by a fan, collects a larger volume of data, ensuring data accuracy to a certain extent.

However, it’s worth noting that high accuracy comes with certain side effects, such as a shorter lifespan for laser sensors compared to infrared sensors. Nevertheless, with continuous technological advancements, most sensors currently perform well.