Fig 1.
Polymer substrate-based nanopore device.
(a) Schematic illustrations of polymer-substrate-based nanopore device consisting of a micro-meter sized pore in a polymer substrate and 20 nm thick free-standing SiN membrane. TEM images of (b) micro-meter size pore drilled in polymer substrate by laser ablation and (c) nanopore with 8 nm diameter drilled by a highly focused electron beam using TEM.
Fig 2.
Process for fabrication of the PI substrate-based Si3N4 nanopore device.
(a) Preparation of polymer film with 75 μm thickness, micro-size hole drilled by laser ablation, transfer of SiN membrane grown by LPCVD onto perforated polymer substrate, and fabrication of nanopore on the suspended SiN membrane using TEM. (b) Optical micrograph of micro-size holes of various diameters and shapes in polymer substrate, formed by laser ablation. The top photo shows the front side and the bottom photo shows the back side. The scale bar is 5 μm. (c) Photograph of SiN membrane on PI substrate. The scale bar is 1 mm.
Fig 3.
Comparison of experimental and simulated conductance for various electrolyte concentrations.
(a) I-V characteristics of polymer-based nanopores, measured with various concentrations of potassium chloride electrolyte. (b) Experimental (red square) and simulated conductance (blue and yellow dotted line) of the polymer-based nanopore device measured at various concentrations of potassium chloride electrolyte.
Fig 4.
Ionic current traces and current power spectral densities with various substrates.
(a) Baseline ionic current traces as a function of time for Si substrate (red), PI substrate (blue), and Pyrex substrate (yellow). (b) Measured power spectral density (PSD) of various substrates. The dashed fitted line represents flicker noise (1/f) of various substrates. All experiments were performed with 1 M KCl at 0 mV with a low-pass filter at 10 kHz.
Table 1.
Comparison of the noise parameters of Si-, Pyrex-, and PI-substrate nanopore devices.
Fig 5.
DNA translocation through PI substrate-based Si3N4 nanopore device.
(a) Ionic conductance trace as function of time with passage of λ-DNA through polymer-substrate-based SiN nanopore. (b) Conductance blockage versus translocation event duration scatter diagram with histogram of λ-DNA translocation at 200 mV for polymer-based nanopore. A Gaussian distribution fit was performed to characterize the average dwell time and conductance blockade.