Development of MEMS-based thermal sensors for gas sensing and vacuum pressure measurements**

气体传感器有助于防止有害气体的扩散，并在具有潜在有害物质风险的地方发挥重要作用，特别是在工业过程和制造工厂中。化学气体传感器是基于气体与敏感材料之间的化学反应，导致检测材料的电导率变化。最近，蒙特利尔的First Sensor Corp公司（一家制造各种传感器设备的公司）开发了一种基于MEMS的热传感器，用于气体的压力和流量测量，具有多种工业应用，特别是在医疗和制药领域。 传感器的进一步商业化需要改进其功能。由于器件的低选择性和有限的分辨率，传感器不能用于分析含有两种以上组分的气体混合物或用于应检测小浓度的某些气体的应用。另一方面，该设备对湿度、温度的变化非常敏感。为了提供进一步商业化器械的机会，需要对器械的设计和特性进行广泛的改进。开发用于热式气体传感器的信号处理算法和高级操作模式，包括在不同过热温度下的操作、温度漂移的补偿、感测元件的内部参数的漂移和降噪例程，将提高设备的性能。开发改进的热式气体传感器需要先进的工程专业知识和先进的实验装置，可以精确调节各种气体混合物，并将环境压力从1个大气压控制到小于1 mTorr。传感器的表征及其电子电路的设计将在Concordia大学ECE系的微/纳米器件实验室中进行，并与First Sensor Corp.的工程师和专业知识合作。

Gas sensors helps to prevent the spread of hazardous gases and play important roles in places with the risk of potentially harmful substances specifically in industrial processes and manufacturing plants. Chemical gas sensors are based on chemical reaction between gas and sensing materials, resulting in change of conductivity of the detector materials. Recently, First Sensor Corp, a company in Montreal fabricating various sensor devices, has developed a MEMS-based thermal sensor for pressure and flow measurements of gases with several industrial applications in particular in medical and pharmaceutical areas. Further commercialization of the sensor requires improvement of its function. Due to the low selectivity and limited resolution of the device, the sensor cannot be used in analyzing gas mixtures containing more than two components or in applications where small concentration of certain gases should be detected. On the other hand, the device is very sensitive to changes in moisture, temperature. To provide opportunities to further commercialize the device, extensive improvement in design and characteristics of the device are required. Development of signal processing algorithms and advanced operating modes for the thermal gas sensor including operation at different overheating temperatures, compensation of temperature drift, drift of internal parameters of the sensing element and noise reduction routines will improve performance of the device. Development of an improved thermal gas sensors requires advanced engineering expertise and advanced experimental setup with possibility to adjust accurately various gas mixtures and control ambient pressure from 1 atmosphere to less than 1mTorr. The characterization of the sensor and design of its electronics circuitry will be performed in the laboratories of Micro/Nano devices in ECE department at Concordia University with collaboration of engineers and expertise of First Sensor Corp. **************