A basic piezoelectric gas sensor operates on the principle of the piezoelectric effect. The piezoelectric effect is a phenomenon in which certain materials generate an electric charge when subjected to mechanical stress or pressure. This property is utilized in gas sensors to detect the presence of specific gases in the environment.
Here's how a basic piezoelectric gas sensor works:
Sensor Construction: The sensor consists of a piezoelectric material, typically a crystal or ceramic, that is sandwiched between two metal electrodes. The piezoelectric material is selected based on the specific gas to be detected.
Gas Interaction: When the target gas comes in contact with the surface of the piezoelectric material, it is absorbed or adsorbed by the material. This gas interaction causes a change in the mass of the piezoelectric material, leading to a mechanical deformation or stress on the crystal structure.
Mechanical Deformation: The gas-induced mechanical stress or deformation causes the crystal lattice structure of the piezoelectric material to alter. This deformation results in a generation of an electric charge within the material.
Electric Signal Generation: The electric charge generated across the piezoelectric material is directly proportional to the amount of gas that has interacted with it. This charge creates a voltage potential difference between the metal electrodes, which results in an electric signal.
Signal Processing: The electric signal from the sensor is then processed by a connected circuit or microcontroller. The signal processing may include amplification, filtering, and calibration to convert the analog signal into a digital format for further analysis.
Gas Detection: The processed signal is compared to predefined thresholds or calibration data to determine the concentration or presence of the target gas. If the gas concentration exceeds a specific threshold, the sensor triggers an alarm or takes appropriate actions, depending on the application.
It is important to note that the sensitivity and selectivity of piezoelectric gas sensors can be influenced by factors like temperature, humidity, and interfering gases, which may require compensation or calibration to ensure accurate gas detection. Additionally, some piezoelectric gas sensors may be designed to detect multiple gases simultaneously by using different piezoelectric materials or sensor configurations.