微型多参数水质传感器芯片的设计及应用

Design and application of miniature multi-parameter water quality sensor chip

针对目前水质参数传感器测量功能单一,且受环境温度影响大等问题,提出了一种具有温度补偿功能的多参数水质传感器芯片。该传感器芯片是使用微机电系统(MEMS)技术制造的,芯片表面集成了pH传感器、DO传感器、氨氮传感器和温度传感器。为实现温度补偿,芯片还设计了一种夹心板式蛇形Pt电阻加热器。同时设计了与芯片相适应的微流控测试腔,以实现水样测量。采用有限元稳态热分析对4种加热器热传递过程进行分析,得到合理的芯片结构布局,通过MEMS工艺制作出传感器芯片。采用自制的恒电位仪测试电路,对传感器芯片性能进行了测试。实验结果表明,pH传感器具有0.288 mA/pH的高灵敏度;溶解氧(DO)传感器的灵敏度为2.22μA/(mg·L-1);氨氮传感器的灵敏度为0.1139 mA/(mg·L-1);温度传感器的灵敏度为0.949Ω/℃;加热器的功率和温度变化灵敏度为0.3126℃/mW。与单个水质参数传感器相比,该传感器芯片体积小、坚固耐用,能够同时检测水样的多种参数,且温度补偿效果较好。

Water-quality sensors feature a single measurement function and are greatly affected by ambient temperature.This paper proposes a multi-parameter water-quality sensor chip with temperature compensation.The sensor chip was manufactured using the micro-electro-mechanical system(MEMS)technology.The chip surface contained integrated pH,dissolved oxygen(DO),ammonia-nitrogen,and temperature sensors.To achieve temperature compensation,the chip was also designed with a sandwich-plate snake Pt resistance heater.At the same time,a microfluidic test chamber that was matched with the chip was designed to realize water-sample measurement.Finite-element steady-state thermal analysis was used to analyze the heat-transfer process of four heaters,and a reasonable chip-structure layout was established.Thereafter,the sensor chip was fabricated using the MEMS technology.The performance of the sensor chip was investigated using a laboratory-developed potentiostat test circuit.Experimental results show that the pH sensor has a high sensitivity of 0.288 mA/pH.The sensitivity of the temperature sensor is 0.949Ω/℃and that of the ammonia-nitrogen sensor was 0.1139 mA/(mg·L-1).The sensitivity of the DO sensor is 2.22μA/(mg·L-1)and that of the temperature sensor,which changes with respect to the heater power,is 0.3126℃/mW.Compared with a single water-quality parameter sensor,the as-prepared sensor chip could simultaneously detect multiple parameters of a water sample and exhibited a good temperature-compensation effect.Moreover,the sensor chip was small in size,robust,and highly accurate.