The handheld ozone concentration detector mainly converts the concentration of ozone gas into electrical signals through sensors, and then processes and calculates the data through circuits, ultimately displaying the ozone concentration in digital or graphical form. The core is to use the chemical or physical properties of ozone to achieve accurate detection.
At present, the mainstream handheld ozone detectors mainly use the following two working principles, with differences in applicable scenarios and accuracy:
1. Principle of electrochemical sensors (commonly used)
This is the mainstream technology of handheld devices currently, which generates electrical signals through the reaction between ozone and chemical substances inside the sensor. The specific process is divided into four steps:
Gas entry: Ozone gas diffuses into the sensing electrode area inside the electrochemical sensor through the inlet of the detector (with dust filtering/dehumidification device).
Electrochemical reaction: The working electrode inside the sensor undergoes an oxidation-reduction reaction with ozone (ozone is reduced), generating a weak current signal, and the current intensity is linearly positively correlated with ozone concentration (the higher the concentration, the greater the current).
Signal conversion: The weak current output by the sensor is processed by the amplification circuit and A/D conversion module inside the detector, and converted into a computable digital signal.
Data display: The processor converts the digital signal into ozone concentration values (usually in ppm or mg/m ³) based on a preset calibration curve (calibrated with standard ozone gas in advance), and finally displays them in real-time on the display screen.
The advantages of this principle are fast response speed (usually less than 30 seconds), small size, low power consumption, and suitability for rapid on-site detection; The disadvantage is that the sensor has a lifespan of 1-2 years, requires regular calibration, and is susceptible to environmental factors such as humidity and temperature.
2. Principle of UV absorption method (high-precision scene)
Based on the physical property of selective absorption of specific wavelengths of ultraviolet light by ozone, it has higher accuracy and is commonly used in scenarios with strict requirements for detection results. The workflow is as follows:
Light source emission: The ultraviolet light source inside the detector (usually emitting 254nm wavelength ultraviolet light, which is strongly absorbed by ozone) emits stable ultraviolet light to the detection chamber.
Gas absorption: After the ozone gas to be detected enters the gas chamber, some ultraviolet light is absorbed by the ozone, and the absorption amount follows Lambert Beer's law (i.e. the degree of absorption is proportional to the concentration of ozone and the length of the gas chamber).
Signal detection: The ultraviolet detector at the other end of the chamber receives the remaining absorbed ultraviolet light and converts it into an electrical signal. The more unabsorbed light, the stronger the electrical signal (negatively correlated with ozone concentration).
Concentration calculation: The processor compares the difference in electrical signals between "with ozone" and "without ozone", combines chamber parameters and law formulas, calculates the ozone concentration, and displays it.
The advantages of this principle are high accuracy (usually less than 2% error), long sensor lifespan (3-5 years), and strong anti-interference ability; The disadvantage is that the device has a relatively large size, high power consumption, and higher cost. Some handheld devices may use simplified UV modules to balance portability and accuracy.