【摘要】 商用玻璃pH电极应用于农业监测中存在探头易碎、接入阻抗大、易极化等问题，该研究利用喷墨打印技术制备了基于单壁碳纳米管介导质子酸掺杂聚苯胺柔性pH传感芯片，通过交流阻抗谱法比较分析了柔性芯片与商用电极在接入阻抗及电荷转移上的优势，系统测试了柔性pH芯片在灵敏度、响应时间、稳定性、重复性、抗干扰性、弯折影响等性能参数，验证了其在无土栽培生菜营养液pH值动态监测中的应用可行性。试验结果表明：柔性pH传感芯片电荷转移阻抗约为230.8?，商用pH传感器达到9 879?，两参数相差40倍以上，柔性pH传感器在频率全谱段皆表现出更为优越的仪器仪表阻抗匹配性能。在pH值2～10范围内，柔性pH传感芯片的灵敏度为–61.9m V/p H，响应时间约为15s,12h内最大漂移不超过5.44 m V，重复性、抗干扰性指标理想，0°～120°弯折影响可忽略，温度变化40℃，柔性传感芯片所测pH值随温度漂移小于0.23，寿命达到14 d。连续10 d的水培生菜pH在线监测中，柔性芯片与商用电极一致性表现出良好，最大误差为0.12，可快速准确监测营养液pH值变化，具有良好农业应用前景。更多还原

【Abstract】 The pH value is an essential physical and chemical parameter in crop growth. The monitoring of pH value is vital for the regulation of crop growth environment and the increase of agricultural production and income. Considering the problems of fragile front-end probe and slow charge transfer caused by large internal impedance in the current traditional commercial pH sensor, a flexible sensor chip based on polyaniline sensing mediated by Single-Walled Carbon Nanotubes was prepared by using inkjet printing technology. The flexible chip comprises a sandwich-type membrane structure, including a polyimide substrate, a nano silver wire layer, a single wall carbon nanotube dielectric layer, and a proton acid doped polyaniline ion-selective membrane. The differences in impedance and charge transfer between flexible p H sensor chip and commercial p H sensor were analyzed by scanning EIS impedance at the electrochemical workstation and analyzing fitting circuit parameters. Compared with the commercial pH sensor on the sensitivity, response time, stability, repeatability, and anti-interference. The 0°～120° bending influences were analyzed. The feasibility was verified through the dynamic pH monitoring in the soilless cultivation. The experimental results show that: firstly, the charge transfer impedance of the flexible pH sensor chip was 230.8 ?. Moreover, the value of the commercial pH sensor was 9 879 ?. The charge transfer impedance of the flexible pH sensor chip was 1/4 of that of the commercial sensor, which confirms the advantages of the flexible pH sensor chip in the advantages of a lower impedance and a faster response. Secondly, the pH detection range of the flexible pH sensor chip was 2～10. The sensitivity was –60.1 mV/pH. The pH detection limit of the commercial pH sensor was 1.68～12.46. The sensitivity was –55.2 mV/pH. The performance of the flexible and commercial pH sensors was similar. The response time of the flexible chip was about 15 s, which was significantly lower than that of the commercial pH sensor, 34 s. In the stability test,the maximum drift of the flexible pH sensor was about 5.44 mV within 12 hours, and the maximum drift of the commercial pH sensor was about 3.4 mV. The pH deviation of the repeatability test of the two sensors was smaller than 0.05. It demonstrated good anti-interference to Na+, K+, Ca2+, Mg2+, and Cl-. The flexible pH chip quickly responded when dripping NaOH or HCl solution. When the flexible pH sensor was bent at 0°～120°, the sensitivity illustrated neglectable changes, and the corresponding maximum deviation was only 15.8 mV. The bending did not affect the accuracy of the flexible pH sensor chip.The maximum absolute error of the flexible pH sensor chip for calibration curve verification was 0.24, the maximum relative error was 6.7%, and the corresponding p H verification value was 3.80. The maximum absolute error of the commercial pH sensor was 0.1, and the corresponding p H verification value was 5.9. The maximum relative error was 2.2%, and the corresponding pH verification value was 3.64. The relative errors of the flexible pH sensor chip and the commercial pH sensor were within 6.7% and 2.2%, respectively. The temperature drift of the flexible sensor chip is less than 0.23, and its service life is more than 14 days. Finally, the flexibility showed good consistency with the commercial pH sensor in the dynamic monitoring of the pH in Hydroponic Lettuce cultivation. The variation range of pH values monitored by the flexible pH sensor chip was from 5.4 to 6.3. Furthermore, the maximum pH monitoring deviation between the flexible pH sensor chip and the commercial pH sensor was 0.12. The flexible pH sensor chip was proven with good consistency and accuracy with the commercial pH sensor, which can quickly and accurately obtain the pH change of the measured nutrient solution.更多还原