The nanopores were characterized using a MFP-3D-SA atomic force microscope produced by Asylum Research (Goleta, CA, USA). The micropores in the Si3N4 film was fabricated PCI-32765 and characterized using Helios NanoLab 600i dual beam (Hillsboro, OR, USA). Fabrication of nanopore-based device The scheme of the fabricated nanofluidic device for biosensing is shown in Figure 1a: two separated liquid cells filled with KCl solution are linked by nanopore chip; certain voltage is applied along the axial direction of

the nanopore, which results in background ion current. The analytes in the electrolytic solution are electrophoretically driven to pass through the nanopore, and the translocation events can be marked by the changes in the background currents. In our work, two kinds of chips, the chip containing micropore in Si3N4-Si film covered by PC nanopores arrays (here ‘nanopores arrays’ means many nanopores which are distributed in a two-dimensional

Baf-A1 mouse area, or many parallel nanochannels which are distributed in a three-dimensional area) and the chip containing only PC nanopore arrays (shown in Figure 1b, c, respectively), were employed for single-molecule sensing. Figure 1 The sensing device. (a) The prototype nanofluidic device based on integrated micro-nano pore for biosensing. The left cell in which the biomolecules are added is the feed cell, and the right cell is the permeation cell. (b) The designed sensing devices were built using only PC nanopore membrane for ionic current detection. (c) The designed sensing devices containing PC nanopore membrane integrated with Si3N4-Si hybrid micropore structure for biomolecule acetylcholine sensing. The micropores in the Si3N4 film were fabricated and integrated with PC nanopore membranes according to the following

steps (Figure 2): (1) a Si3N4 film (thickness about 100 nm) on one side of the Si chip (5 mm × 5 mm) was obtained by low-pressure chemical vapor selleck inhibitor deposition (LPCVD) method, (2) a window on top of the chip at the Si side was fabricated by wet etching using tetramethylammonium hydroxide (TMHA), (3) the artificial micropores on the Si3N4 film were fabricated and characterized using focused ion beam (FIB) and scanning electron microscope (SEM), and (4) the Si3N4 micropore was covered by PC membrane containing nanopores (pore size 50 nm) and sealed using polydimethylsiloxane (PDMS). After these steps, hybrid chips were obtained for further nanofluidic device integration and biosensing. Figure 2 Illustration of the integration process of micropore. (1) Si3N4film on one side of the Si chip was obtained by LPCVD method. (2) A window on the top of chip at Si side was fabricated by wet etching. (3) Artificial micropores on the Si3N4film were fabricated by FIB. (4) PC membrane was covered on the Si3N4pore and sealed using PDMS.