4:15 PM - 4:30 PM
[MTT38-04] Characterization of MEMS atmospheric pressure sensors for infrasound observation utilization
Keywords:Barometric pressure sensors, pressure gauge calibration, temperature characteristics
In the observation of infrasound for measuring micro-pressure fluctuations, small pressure variations in the range of several Pa to tens of Pa, with frequencies below approximately 20 Hz, have traditionally been measured using high-precision pressure gauges or microphones. On the other hand, in recent years, the performance of atmospheric pressure sensors using MEMS (Microelectromechanical Systems) technology has been improving. These sensors are small and inexpensive, making it easy to install numerous sensors, thus they have begun to be used for multi-point observations to analyze atmospheric phenomena. However, MEMS sensors are generally known to have temperature dependencies. When sensors are installed in environments close to the outdoors, variations in temperature and humidity may affect measurement performance. Information regarding the temperature coefficients of each sensor is not always provided in the manufacturer's specifications. Even if such information is available, the method of specification varies among manufacturers, and it is often unclear how these values were obtained by testing. As a result, comparing the performance of sensors becomes difficult. Additionally, responsiveness to detect small pressure fluctuations in the range of several Pa is also crucial. Therefore, we conducted a uniform evaluation on several types of MES atmospheric pressure sensors, focusing on their characteristics regarding temperature, humidity, and responsiveness.
For the evaluation of temperature and humidity characteristics, MEMS sensors were placed in a constant temperature and humidity chamber, and the temperature and humidity inside the chamber were changed step by step. The output of the sensors during the temperature and humidity change was compared with the output of a reference atmospheric pressure gauge placed outside the chamber (at room temperature). Temperature was varied from -20 °C to 50 °C while keeping humidity constant to 50 %, and humidity was varied from 40% to 90% while keeping temperature constant to 23 °C. As a result, it was found that the absolute values of temperature coefficients ranged from 0.1 Pa/K to approximately 7 Pa/K, indicating significant variations in temperature characteristics depending on the model. It was also observed that the output of some models was influenced by humidity. For commonly used models, individual differences in temperature and humidity characteristics were examined revealing generally consistent temperature characteristics but some variation in humidity characteristics.
Next, for the evaluation of sensor responsiveness, MEMS sensors were fixed to a table of a vertical electric actuator and subjected to atmospheric pressure fluctuations by moving the table up and down to confirm responsiveness. A height variation of approximately 87 mm corresponds to a pressure change of approximately 1 Pa in the laboratory environment. Results showed that when fluctuations ranging from 1 Pa to 10 Pa were applied at a frequency of 1 Hz, some sensors could detect even a 1 Pa pressure change, while others were unable to detect a 1 Pa pressure change buried within the output noise or produced large output values in response to input. It is important to note the various characteristics when precise atmospheric pressure observations are required. This presentation will report on the details of the evaluation.
For the evaluation of temperature and humidity characteristics, MEMS sensors were placed in a constant temperature and humidity chamber, and the temperature and humidity inside the chamber were changed step by step. The output of the sensors during the temperature and humidity change was compared with the output of a reference atmospheric pressure gauge placed outside the chamber (at room temperature). Temperature was varied from -20 °C to 50 °C while keeping humidity constant to 50 %, and humidity was varied from 40% to 90% while keeping temperature constant to 23 °C. As a result, it was found that the absolute values of temperature coefficients ranged from 0.1 Pa/K to approximately 7 Pa/K, indicating significant variations in temperature characteristics depending on the model. It was also observed that the output of some models was influenced by humidity. For commonly used models, individual differences in temperature and humidity characteristics were examined revealing generally consistent temperature characteristics but some variation in humidity characteristics.
Next, for the evaluation of sensor responsiveness, MEMS sensors were fixed to a table of a vertical electric actuator and subjected to atmospheric pressure fluctuations by moving the table up and down to confirm responsiveness. A height variation of approximately 87 mm corresponds to a pressure change of approximately 1 Pa in the laboratory environment. Results showed that when fluctuations ranging from 1 Pa to 10 Pa were applied at a frequency of 1 Hz, some sensors could detect even a 1 Pa pressure change, while others were unable to detect a 1 Pa pressure change buried within the output noise or produced large output values in response to input. It is important to note the various characteristics when precise atmospheric pressure observations are required. This presentation will report on the details of the evaluation.