Uram Jeffrey D, Ke Kevin, Mayer Michael
Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
ACS Nano. 2008 May;2(5):857-72. doi: 10.1021/nn700322m.
Nanopores and submicrometer pores have recently been explored for applications ranging from detection of single molecules, assemblies of nanoparticles, nucleic acids, occurrence of chemical reactions, and unfolding of proteins. Most of these applications rely on monitoring electrical current through these pores, hence the noise and signal bandwidth of these current recordings are critical for achieving accurate and sensitive measurements. In this report, we present a detailed theoretical and experimental study on the noise and signal bandwidth of current recordings from glass and polyethylene terephthalate (PET) membranes that contain a single submicrometer pore or nanopore. We examined the theoretical signal bandwidth of two different pore geometries, and we measured the signal bandwidth of the electronics used to record the ionic current. We also investigated the theoretical noise generated by the substrate material, the pore, and the electronics used to record the current. Employing a combination of theory and experimental results, we were able to predict the noise in current traces recorded from glass and PET pores with no applied voltage with an error of less than 12% in a range of signal bandwidths from 1 to 40 kHz. In approximately half of all experiments, application of a voltage did not significantly increase the noise. In the other half of experiments, however, application of a voltage resulted in an additional source of noise. For these pores, predictions of the noise were usually still accurate within 35% error at signal bandwidths of at least 10 kHz. The power spectra of this extra noise suggested a 1/f(alpha) origin with best fits to the power spectrum for alpha = 0.4-0.8. This work provides the theoretical background and experimental data for understanding the bandwidth requirements and the main sources of noise in current recordings; it will be useful for minimizing noise and achieving accurate recordings.
最近，纳米孔和亚微米孔已被用于多种应用，范围涵盖单分子检测、纳米颗粒组装体、核酸、化学反应的发生以及蛋白质的解折叠。这些应用大多依赖于监测通过这些孔的电流，因此这些电流记录的噪声和信号带宽对于实现准确和灵敏的测量至关重要。在本报告中，我们对来自含有单个亚微米孔或纳米孔的玻璃和聚对苯二甲酸乙二酯（PET）膜的电流记录的噪声和信号带宽进行了详细的理论和实验研究。我们研究了两种不同孔几何形状的理论信号带宽，并测量了用于记录离子电流的电子设备的信号带宽。我们还研究了由基底材料、孔以及用于记录电流的电子设备产生的理论噪声。通过结合理论和实验结果，我们能够预测在1至40 kHz信号带宽范围内，在无外加电压情况下从玻璃和PET孔记录的电流迹线中的噪声，误差小于12%。在大约一半的所有实验中，施加电压并未显著增加噪声。然而，在另一半实验中，施加电压导致了额外的噪声源。对于这些孔，在至少10 kHz的信号带宽下，噪声预测通常仍能在35%的误差范围内保持准确。这种额外噪声的功率谱表明其起源为1/f(α)，最适合α = 0.4 - 0.8时的功率谱。这项工作为理解电流记录中的带宽要求和主要噪声源提供了理论背景和实验数据；它将有助于最小化噪声并实现准确记录。
