Nguyen Cuong M, Rao Smitha, Yang Xuesong, Dubey Souvik, Mays Jeffrey, Cao Hung, Chiao Jung-Chih
Department of Electrical Engineering, University of Texas, Arlington, TX 76019, USA.
Department of Electrical Engineering, ETS, Montreal, QC H3C 1K3, Canada.
Sensors (Basel). 2015 Feb 12;15(2):4212-28. doi: 10.3390/s150204212.
Flexible iridium oxide (IrOx)-based micro-electrodes were fabricated on flexible polyimide substrates using a sol-gel deposition process for utilization as integrated pseudo-reference electrodes for bio-electrochemical sensing applications. The fabrication method yields reliable miniature on-probe IrOx electrodes with long lifetime, high stability and repeatability. Such sensors can be used for long-term measurements. Various dimensions of sol-gel iridium oxide electrodes including 1 mm × 1 mm, 500 µm × 500 µm, and 100 µm × 100 µm were fabricated. Sensor longevity and pH dependence were investigated by immersing the electrodes in hydrochloric acid, fetal bovine serum (FBS), and sodium hydroxide solutions for 30 days. Less pH dependent responses, compared to IrOx electrodes fabricated by electrochemical deposition processes, were measured at 58.8 ± 0.4 mV/pH, 53.8 ± 1.3 mV/pH and 48 ± 0.6 mV/pH, respectively. The on-probe IrOx pseudo-reference electrodes were utilized for dopamine sensing. The baseline responses of the sensors were higher than the one using an external Ag/AgCl reference electrode. Using IrOx reference electrodes integrated on the same probe with working electrodes eliminated the use of cytotoxic Ag/AgCl reference electrode without loss in sensitivity. This enables employing such sensors in long-term recording of concentrations of neurotransmitters in central nervous systems of animals and humans.
采用溶胶 - 凝胶沉积工艺在柔性聚酰亚胺基板上制备了基于柔性氧化铱（IrOx）的微电极，用作生物电化学传感应用的集成伪参比电极。该制备方法可得到具有长寿命、高稳定性和可重复性的可靠微型探针上IrOx电极。此类传感器可用于长期测量。制备了各种尺寸的溶胶 - 凝胶氧化铱电极，包括1 mm×1 mm、500 µm×500 µm和100 µm×100 µm。通过将电极浸入盐酸、胎牛血清（FBS）和氢氧化钠溶液中30天来研究传感器的寿命和pH依赖性。与通过电化学沉积工艺制备的IrOx电极相比，测得的pH依赖性响应较小，分别为58.8±0.4 mV/pH、53.8±1.3 mV/pH和48±0.6 mV/pH。将探针上的IrOx伪参比电极用于多巴胺传感。传感器的基线响应高于使用外部Ag/AgCl参比电极时的响应。使用与工作电极集成在同一探针上的IrOx参比电极，无需使用具有细胞毒性的Ag/AgCl参比电极，且灵敏度无损失。这使得此类传感器能够用于长期记录动物和人类中枢神经系统中神经递质的浓度。
