Noise and Bandwidth of Current Recordings from Submicrometer Pores and Nanopores

Abstract

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.

Generalized Noise Study of Solid-State Nanopores at Low Frequencies

“…dielectric and capacitive, are mainly related to the capacitance of the system. 27,39,40 According to the geometry and material of our nanopore chip, the parasitic capacitance is estimated to be 30 pF. As the amplitude of the 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 7 where, α H the Hooge parameter and N c is the total number of conducting carriers.…”

On nanopore DNA sequencing by signal and noise analysis of ionic current

“…[60][61][62] The noise level of the measurement system can be very low when proper measures are taken. [61] In general, use of a wider bandwidth of a system invites a higher noise level. [61,63] However, the choice of bandwidth is not without constraints; it should be larger than the frequency of the nt translocation (i.e., reciprocal of the translocation speed).…”

“…[61] In general, use of a wider bandwidth of a system invites a higher noise level. [61,63] However, the choice of bandwidth is not without constraints; it should be larger than the frequency of the nt translocation (i.e., reciprocal of the translocation speed). It is difficult to make bandwidth very small by utilizing filters in the measurement circuit, since, otherwise, details in ΔI or ΔI/Io risk to be filtered out as well.…”

“…For good resolution and acquisition of enough details, the translocation frequency is suggested to be 3-5 times smaller than the bandwidth. [61] …”

Solid-State Nanopore Sensors for Nucleic Acid Analysis

“…Two dominant sources of noise have been documented in the literature: a low frequency current fluctuation with 1/f characteristics (flicker noise) and a high-frequency background noise component associated with the capacitance of the Si support chip (dielectric noise). [86][87][88][89][90][91] Minimizing these respective noise components is integral to improving the sensitivity and signal-to-noise ratio of nanopore sensors.…”