The Institute of Scientific and Industrial Research, Osaka University, Japan.
Nanoscale. 2017 Mar 23;9(12):4076-4081. doi: 10.1039/c6nr09278k.
Reliable ways of DNA sequencing by tunnelling current require low-noise and high-speed measurements of tunnelling current in aqueous environments. Here we report a use of insulator-protected nanoprobes for achieving 7.6 pA rms noise at 50 kHz sampling rates in an electrolyte solution. We utilized dielectric-covered mechanically-controllable break junctions to create a pair of nano-exposed insulator/Au coaxial electrodes closely separated by 1 nm. We observed insulator layer thickness dependent noise levels, which was attributed to decreased capacitance through replacing capacitive electric double layers by the low-k dielectrics. We also demonstrated the detection of sharpened features in tunnelling current signatures that reflect dynamic motions of single-nucleotides in the electrode gaps by virtue of suppressed smearing effects in the low-capacitance nanoelectrode system.
隧穿电流可靠的 DNA 测序方法需要在水相环境中对隧穿电流进行低噪声和高速测量。在这里，我们报告了一种利用绝缘层保护的纳米探针在电解质溶液中以 50 kHz 的采样率实现 7.6 pA rms 噪声的方法。我们利用介电覆盖的机械可控断裂结来创建一对纳米暴露的绝缘体/金同轴电极，它们通过 1nm 的距离紧密隔开。我们观察到了与绝缘层厚度相关的噪声水平，这归因于通过用低 k 介电材料替代电容双电层，降低了电容。我们还通过在低电容纳米电极系统中抑制模糊效应，展示了隧穿电流特征中尖锐特征的检测，这些特征反映了电极间隙中单核苷酸的动态运动。
