用于氨氮检测的薄层氨气微传感芯片及其系统研究

Thin Layer Ammonia Microsensor Chip and System for Measurement of Ammonia Nitrogen

设计并制备了一种具有微池薄液层结构的氨气微传感芯片,并构建了以此微传感芯片为敏感单元的氨氮检测系统,探索了使用安培型氨气微传感器检测氨氮的方法。此微传感芯片采用MEMS工艺制备,通过电化学方法在微电极表面修饰了对氨具有良好电催化氧化性能的纳米铂,提高了传感器的灵敏度。在芯片的SU-8微池中滴入微量碳酸丙烯酯(PC),形成可使氨气迅速扩散到电极表面的薄层电解液,使传感器具有较快的响应速度。使用自行设计的氨氮检测系统对氨氮进行检测,考察了氨氮检测的浓度响应特性、时间响应特性、重复性及选择性。氨氮检测系统的线性范围为0.1～5.0 mg/L;检测下限为0.1 mg/L;响应时间小于1 min;重复性偏差为4.0%。

An ammonia microsensor chip based on a thin liquid layer in micro-pool has been designed and prepared.An ammonia nitrogen measurement system utilizing such a miniaturized sensor chip has been constructed.The method of ammonia nitrogen measurement using an amperometric ammonia microsensor was investigated.The sensor chip was fabricated by microelectromechanical system（MEMS）.Platinum nanoparticles,possessing excellent electrochemical catalysis to ammonia,were modified on the bare microelectrodes of the sensor by electrochemical methods to enhance the sensitivity.A tiny amount of propylene carbonate（PC） was dripped into SU-8 micro-pool to form the thin layer electrolyte which facilitated ammonia to diffuse to the microelectrode surface,thus achieving a fast response time.Measurement of ammonia nitrogen using the self-designed measurement system was presented.The characterizations of the sensor,including relationship between response and sample concentration,response times,reproducibility and selectivity were demonstrated.A linear calibration curve between 0.1-5 mg/L was obtained.Meanwhile a limit of detection,0.1 mg/L,was achieved.The response time was less than 1 minute.The relative standard deviation（RSD） was 4.0%.