Development of a Portable PM2.5 Sensing System
Date Issued
2014
Date
2014
Author(s)
Tsai, Po-Tsun
Abstract
Asthma attacks of the patients can be triggered by several environmental pollutants. One of the most significant pollutants in our environmental is PM2.5 particles (diameter of the particulate matters smaller than 2.5um). Some of poisonous materials such as polycyclic aromatic hydrocarbon (PAHs) are easily attached to the surface of PM2.5 particles and can be absorbed by the asthma patients through breathing or food chain. Traditional measurements of PM2.5 are typically performed in a fixed station. However, this measurement by a station is not suitable for the real time monitoring to track the asthma patients activities. In addition, the analysis system of the PM2.5 is also very expensive.
In this research, we aimed to develop a real time and portable particle sensor which asthma patients can use to monitor their exposure during daily activities. The system consisting of a portable air pump, a sensor, an interface circuit and a laptop can monitor the particle concentration and calculate the real time data simultaneously. Two sensors were characterized in this study. The first one is a commercially available QCM and the other one is a CMOS MEMS capacitance sensor with the comb structures fabricated through a commercial 0.35μm 2 polysilicon and 4 metal CMOS MEMS process followed by the self-developed post processes. The comb structure design has 104 gaps between electrodes. When PM2.5 particles fall in between the gap, the dielectric constant in between two electrodes is increased, and then the overall capacitance value of the sensor is increased as well. The sensitivity of the sensor is approximately 1.00*10^-2~1.20*10^-2pF/μg under different environmental conditions. Finally, the influences of humidity and temperature were removed from our study with a model and a portable and real time air quality monitoring for asthma patients can be realized.
Subjects
微機電系統
PM2.5
石英晶體微天平
電容感測器
梳狀電極電容
可攜式系統
微粒感測器
氣喘
Type
thesis
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