Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
ACS Nano. 2013 Jun 25;7(6):5483-90. doi: 10.1021/nn401542x. Epub 2013 Jun 3.
An array of nanoscale-recessed ring-disk electrodes was fabricated using layer-by-layer deposition, nanosphere lithography, and a multistep reactive ion etching process. The resulting device was operated in generator-collector mode by holding the ring electrodes at a constant potential and performing cyclic voltammetry by sweeping the disk potential in Fe(CN)6(3-/4-) solutions. Steady-state response and enhanced (~10×) limiting current were achieved by cycling the redox couple between ring and disk electrodes with high transfer/collection efficiency. The collector (ring) electrode, which is held at a constant potential, exhibits a much smaller charging current than the generator (disk), and it is relatively insensitive to scan rate. A characteristic feature of the nanoscale ring-disk geometry is that the electrochemical reaction occurring at the disk electrodes can be tuned by modulating the potential at the ring electrodes. Measured shifts in Fe(CN)6(3-/4-) concentration profiles were found to be in excellent agreement with finite element method simulations. The main performance metric, the amplification factor, was optimized for arrays containing small diameter pores (r < 250 nm) with minimum electrode spacing and high pore density. Finally, integration of the fabricated array within a nanochannel produced up to 50-fold current amplification as well as enhanced selectivity, demonstrating the compatibility of the device with lab-on-a-chip architectures.
采用层层沉积、纳米球光刻和多步反应离子刻蚀工艺，制备了纳米级凹陷环盘电极阵列。通过将环电极保持在恒定电位，并在 Fe(CN)6(3-/4-)溶液中通过扫盘电位进行循环伏安法，使所得器件以发生器-收集器模式工作。通过在环和盘电极之间以高传输/收集效率循环氧化还原对，实现了稳态响应和增强（约 10 倍）的极限电流。收集器（环）电极保持在恒定电位，其充电电流比发生器（盘）小得多，并且对扫描速率相对不敏感。纳米级环盘几何形状的一个特征是，可以通过调节环电极的电位来调节在盘电极上发生的电化学反应。测量到的 Fe(CN)6(3-/4-)浓度分布的偏移与有限元方法模拟非常吻合。对于包含小孔径（r < 250nm）、最小电极间距和高密度孔的阵列，主要性能指标（放大因子）进行了优化。最后，将所制备的阵列集成到纳米通道内，产生了高达 50 倍的电流放大和增强的选择性，证明了该器件与片上实验室架构的兼容性。
