基于硅桥的新型甲醛气体传感器的研究

Study on novel formaldehyde vapor sensor based on Si bridge

提出了一种基于高分子薄膜溶胀效应的新型MEMS压阻式甲醛气体传感器,其结构由嵌入惠斯通电桥的硅桥和一层改性丙烯酸酯气敏薄膜构成,敏感薄膜因吸收甲醛气体发生溶胀使硅桥上的惠斯通电桥产生输出电压,从而实现对甲醛气体的检测。基于弹性力学薄板原理构建了该气体传感器中硅桥与改性丙烯酸酯薄膜相互作用的模型,并推导出传感器的输出公式。实验结果验证了理论分析模型,实验结果表明该传感器有很好的线性,选择性。实验测得该传感器灵敏度为0.975×106ecr,分辨率为10×10-6,响应时间和恢复时间分别为50 s和65 s。该传感器结构简单、无须加热,工艺成熟、成本低,应用MEMS工艺技术可实现与信号处理电路的集成。

A novel MEMS formaldehyde vapor sensor is proposed based on swelling effect,which is composed of a silicon sensitive diaphragm of silicon bridge embedded in a piezoresistive Wheatstone bridge and a acrylic adhesive modified thin polymer layer.The swelling of the polymer layer leads to the bending of the Si bridge,which causes the piezoresistive Wheatstone bridge to generate an output voltage.A theoretical model of the interaction between the Si bridge and polymer layer is presented based on elastic mechanics theory and an output expression of the gas sensor is proposed.Experimental results verify the model of the sensor.The novel sensor has good linearity and selectivity.Experimental results show that the sensitivity,resolution,response time and recovery time are 0.975uV/ppm,10ppm,50s and 65s,respectively.The proposed sensor features simply principle,mature technology,low cost;and can be integrated with signal processing circuit using MEMS processes.