Nanogap Electrochemistry and Sensor Technology at the Molecular Limit

具有电化学刺激和读出功能的传感器在气体、环境和医学痕量分析中得到了广泛的应用。低成本和可靠性以及小型化是商业化和大规模生产的主要因素，特别是廉价的丝网印刷传感器在医疗葡萄糖传感领域占据主导地位。这些设备的低成本一直是其商业成功和广泛销售的秘诀。更强大的发电机集电极系统最初由Nekrasov和Frumkin开发，然后进一步开发用于旋转环盘系统，双和交叉带电极系统，在SECM和STM中，以及在双流道系统中。微电极阵列的工作已被报道用于电分析和DNA合成器的图案。然而，在这些器件中，电极间的间隙一直相对较大，并且亚微米间隙的潜在优势尚未得到开发。在这个项目中，我们提出(i)开发极小的间隙系统，以达到单分子检测的极限；（ii）为强大的传感器设计新的双恒电位结技术，用于广泛的应用。我们的项目假设是，具有100纳米或更小电极间隙的结电极允许开发和研究新的（电）化学传感器过程，这些过程在以前的研究中没有被考虑/实现，例如使用传统的SECM和STM或使用单电极电化学过程的研究。结电极的形成是基于一种强大的（廉价、快速和可重复的）电沉积方法，这将需要针对特定应用进行改进和优化。将开发新的实验方案来控制表面粗糙度，改善生长和几何形状，引入新的结材料，并涂覆/填充传感器结。将研究结内的扩散，并生成短寿命的中间体（例如HS）。, O2。, O3。以及在一个（或多个）调制器电极上产生试剂脉冲的调制器-传感器实验。具有特别优化的脉冲序列的多维脉冲伏安法将提供更高的灵敏度和更高的选择性，并允许不寻常的检测模式（例如，基于氢氧化物脉冲，参见氢氧化物脉冲辅助中性溶液中的葡萄糖检测）。双盘或带电极系统和结电极的数值模拟（基于新的GPU方法）具有挑战性，将为物理现象、化学机制和传感器优化提供重要的见解。

Sensors with electrochemical stimulus and read-out have found wide-spread use in gas, environmental, and medical trace analysis. Low cost and reliability as well as miniaturisation are major factors in commercialisation and mass production and in particular cheap screen printed sensors have dominated for example in the medical glucose sensing field. The low cost of these devices has been the secret to their commercial success and wide distribution. More powerful generator-collector electrode systems have been initially developed by Nekrasov and Frumkin and then further developed for rotating ring-disc systems, dual and interdigitated band electrode systems, in SECM and in STM, as well as in dual flow channel systems. Work with microelectrode arrays has been reported for electroanalysis and for patterning in DNA synthesisers. However, in these devices the inter-electrode gap has always been relatively large and the potential benefits of sub-micron gaps have not been exploited. In this project we propose (i) to develop extremely small gap systems to reach the limit of single molecule detection and (ii) to device novel bipotentiostat junction technology for powerful sensors for a wide range of applications.Our project hypothesis is that junction electrodes with 100 nm or less inter-electrode gap allow novel (electro-)chemical sensor processes to be exploited and investigated which have not been considered/realised in previous studies e.g. using conventional SECM and STM or in studies employing single-electrode electrochemical processes. The junction electrode formation is based on a robust (cheap, fast, & reproducible) electro-deposition approach which will need refinement and optimisation for particular applications. New experimental protocols will be developed to control surface roughness, improve growth & geometry, to introduce new junction materials, and to coat/fill sensor junctions. Diffusion within the junction will be investigated and short lived intermediates generated (for example HS., O2., O3., and other radical species) and modulator-sensor experiments conducted where pulses of reagents are generated at one (or more) modulator electrodes. Multi-dimensional pulse voltammetry with specifically optimised pulse sequences will provide higher sensitivity and higher selectivity and allow unusual detection modes (e.g. based on hydroxide pulses, see glucose detection in neutral solution aided by hydroxide pulses). The numerical simulation (based on new GPU methods ) of dual disc or band electrode systems and for junction electrodes is challenging and will provide important insight into physical phenomena, chemical mechanisms, and sensor optimisation.