Yin Jiawen, Zhang Wei, Zhang Zan, Jin Han, Gao Wanlei, Jian Jiawen, Jin Qinghui
Faculty of Electrical Engineering and Computer Science, Ningbo University Ningbo 315211 P. R. China
State Key Laboratory of Transducer Technology, Center for Excellence in Superconducting Electronics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences Shanghai 200050 P. R. China
RSC Adv. 2019 Jun 25;9(34):19699-19706. doi: 10.1039/c9ra01987a. eCollection 2019 Jun 19.
The reference electrode (RE) provides a stable potential for electrochemical detection; therefore, the RE plays an important role in environmental monitoring. In this paper, a novel batch of microfabricated silicon-base miniaturized Ag/AgCl RE was reported. A specially designed mini-tank for saturated KCl solution storage and a nanochannel array for ion-exchange were fabricated on a 4 inch (100) silicon wafer using a two-step KOH anisotropic etching process. An Ag/AgCl electrode was fabricated on a 4 inch Pyrex 7740 glass substrate. Finally, the finished silicon and glass substrates were anode bonded to form the entire system. By comparing with a conventional solid-state Ag/AgCl RE in electrochemical microsensors, a pre-packaged saturated KCl solution in the mini-tank provided a stable working environment for the Ag/AgCl electrode to ensure a constant reference potential. Compared with a routine glass-structured RE and by replacing the ion-exchange membrane with a nanochannel array, the miniaturized RE achieved a longer lifetime. The size of the finished miniaturized RE electrode was 11 mm × 14 mm. The reference potential variation was only 0.1 mV under continuous testing for 3000 s. The standard deviation in the reference potential was only 1.314 mV in different NaSO buffer concentrations ranging from 3 mM to 30 mM. To verify the practicality of the novel silicon-base miniaturized RE, the fabricated RE was applied to measure the amount of nitrite in a water sample and achieved a better linearity of = 0.998. This miniaturized RE showed better reference potential stability and consistency because of the batch fabrication technique. This novel strategy for the design and manufacture of the miniaturized RE shows a bright future in the wide use of electrochemical sensors in online monitoring of water pollutants.
参比电极（RE）为电化学检测提供稳定的电位；因此，参比电极在环境监测中起着重要作用。本文报道了一批新型的微纳加工硅基小型化Ag/AgCl参比电极。采用两步KOH各向异性蚀刻工艺，在4英寸（100）硅片上制作了一个专门设计的用于储存饱和KCl溶液的微型槽和一个用于离子交换的纳米通道阵列。在4英寸派热克斯7740玻璃衬底上制作了Ag/AgCl电极。最后，将完成的硅和玻璃衬底进行阳极键合以形成整个系统。通过与电化学微传感器中的传统固态Ag/AgCl参比电极进行比较，微型槽中预封装的饱和KCl溶液为Ag/AgCl电极提供了稳定的工作环境，以确保恒定的参比电位。与常规玻璃结构的参比电极相比，通过用纳米通道阵列代替离子交换膜，小型化参比电极实现了更长的使用寿命。制成的小型化参比电极的尺寸为11 mm×14 mm。在连续测试3000 s的情况下，参比电位变化仅为0.1 mV。在3 mM至30 mM的不同NaSO缓冲液浓度下，参比电位的标准偏差仅为1.314 mV。为了验证新型硅基小型化参比电极的实用性，将制作的参比电极应用于测量水样中的亚硝酸盐含量，线性度较好，为 = 0.998。由于采用了批量制造技术，这种小型化参比电极显示出更好的参比电位稳定性和一致性。这种设计和制造小型化参比电极的新策略在电化学传感器广泛用于水污染物在线监测方面展现出光明的前景。
