A FIB induced boiling mechanism for rapid nanopore formation

Surface Roughness Effects on Confined Nanoscale Transport of Ions and Biomolecules

Biological channels, especially membrane proteins, play a crucial role in metabolism, facilitating the transport of nutrients and other materials across cell membranes in a bio-electrolyte environment. Artificial nanopores are employed to study ion and biomolecule transport behavior inside. While the non-specific interaction between the nanopore surface and transport targets has garnered significant attention, the impact of surface roughness is overlooked. In this study, Nanopores with different levels of inner surface roughness is created by adjusting the FIB (Focus Ion Beam) fabrication parameters. Experiments and molecular dynamics (MD) simulations are employed to demonstrate that greater roughness results from larger FIB beam currents and shorter processing times. Lower roughness increases the capture rate of biomolecules, while greater roughness enhances the normalized blockade current (ΔI/I0 ). The phenomenon of rougher nanopores are attributed to a barrier-dominated capture mechanism and more likely to induce DNA folding. This transport barrier exists in rough nanopores by utilizing steer molecular dynamics (SMD) simulations to investigate the force profile of a dA10 DNA molecule during translocation is demonstrated. This work illustrates how surface roughness influences the ionic current features and the translocation of biomolecules, paving a new way for tunning the molecule transport in nanopores.

Recent advances in focused ion beam nanofabrication for nanostructures and devices: fundamentals and applications

The past few decades have witnessed growing research interest in developing powerful nanofabrication technologies for three-dimensional (3D) structures and devices to achieve nano-scale and nano-precision manufacturing. Among the various fabrication techniques, focused ion beam (FIB) nanofabrication has been established as a well-suited and promising technique in nearly all fields of nanotechnology for the fabrication of 3D nanostructures and devices because of increasing demands from industry and research. In this article, a series of FIB nanofabrication factors related to the fabrication of 3D nanostructures and devices, including mechanisms, instruments, processes, and typical applications of FIB nanofabrication, are systematically summarized and analyzed in detail. Additionally, current challenges and future development trends of FIB nanofabrication in this field are also given. This work intends to provide guidance for practitioners, researchers, or engineers who wish to learn more about the FIB nanofabrication technology that is driving the revolution in 3D nanostructures and devices.

Folding 2D Structures into 3D Configurations at the Micro/Nanoscale: Principles, Techniques, and Applications

Compared to their 2D counterparts, 3D micro/nanostructures show larger degrees of freedom and richer functionalities; thus, they have attracted increasing attention in the past decades. Moreover, extensive applications of 3D micro/nanostructures are demonstrated in the fields of mechanics, biomedicine, optics, etc., with great advantages. However, the mainstream micro/nanofabrication technologies are planar ones; therefore, they cannot be used directly for the construction of 3D micro/nanostructures, making 3D fabrication at the micro/nanoscale a great challenge. A promising strategy to overcome this is to combine the state-of-the-art planar fabrication techniques with the folding method to produce 3D structures. In this strategy, 2D components can be easily produced by traditional planar techniques, and then, 3D structures are constructed by folding each 2D component to specific orientations. In this way, not only will the advantages of existing planar techniques, such as high precision, programmable patterning, and mass production, be preserved, but the fabrication capability will also be greatly expanded without complex and expensive equipment modification/development. The goal here is to highlight the recent progress of the folding method from the perspective of principles, techniques, and applications, as well as to discuss the existing challenges and future prospectives.