Electrochemical sensing of Hg(II) ions based on ultramicrotome-crafted strip ultramicroelectrode.

The presence of heavy metal ions in the biosphere constitutes a significant source of pollution, posing severe threats to both human health and the environment. Thus, the accurate detection of heavy metal ions assumes paramount importance. The present study involves the preparation of electrochemical sensors based on strip ultramicroelectrode, enabling the detection of Hg.

Fabrication of disk ultramicroelectrode using nanoskiving method.

The detection time of the ultramicroelectrode can be reduced to nanoseconds when compared to the macroscopic electrode, enabling real-time monitoring of the instantaneous electrochemical behavior of the microstructure. Preparing ultramicroelectrode thus has drawn great attention recently. In the present study, a novel method for the preparation of disk ultramicroelectrodes with controllable electrode end sizes based on the nanoskiving method is proposed.

Nanoskiving of van der Waals Materials toward Edge/Basal Plane Contact Heterojunctions for High-Performance Photodetection.

The unique features of edges in van der Waals materials may lead to edge-basal plane contacts that could provide new opportunities for electronic and optoelectronic devices. However, few studies have addressed edge/basal plane contact heterojunctions owing to the formidable challenges in integrating edges with the basal plane to form a heterojunction. Here, taking the example of black phosphorus (BP)/ReS, a heterojunction with contact between the edge and the basal plane was successfully achieved by the introduction of a nanoskiving technique to fabricate BP edges with controlled orientation, followed by the dry transfer of a ReS flake.

Periodic Folded Gold Nanostructures with a Sub-10 nm Nanogap for Surface-Enhanced Raman Spectroscopy.

Surface-enhanced Raman spectroscopy has emerged as a powerful spectroscopy technique for detection with its capacity for label-free, nondestructive analysis, and ultrasensitive characterization. High-performance surface-enhanced Raman scattering (SERS) substrates with homogeneity and low cost are the key factors in chemical and biomedical analysis. In this study, we propose the technique of atomic force microscopy (AFM) scratching and nanoskiving to prepare periodic folded gold (Au) nanostructures as SERS substrates.

Local Nanostrain Engineering of Monolayer MoS Using Atomic Force Microscopy-Based Thermomechanical Nanoindentation.

Strain engineering in two-dimensional materials (2DMs) has important application potential for electronic and optoelectronic devices. However, achieving precise spatial control, adjustable sizing, and permanent strain with nanoscale resolution remains challenging. Herein, a thermomechanical nanoindentation method is introduced, inspired by skin edema caused by mosquito bites, which can induce localized nanostrain and bandgap modulation in monolayer molybdenum disulfide (MoS) transferred onto a poly(methyl methacrylate) film utilizing a heated atomic force microscopy nanotip.

Morphology measurements by AFM tapping without causing surface damage: A phase shift characterization.

The morphology measurement of a surface can be done by using an atomic force microscope (AFM). However, it is difficult to ensure that the measurement does not introduce any damage to the sample surface. This paper proposes that phase shift, the phase change between the original surface and scanned area, can provide a characteristic signal of the tip-surface interaction.

A probe-based nanometric morphology measurement system using intermittent-contact mode.

In the present study, a homemade probe-based nanometric morphology measurement system is proposed, which can be easily integrated with other probes, such as a diamond probe and an electrochemical electrode. In this system, an intermittent-contact mode is adopted, which is based on a set of micro-force servo modules. The micro-force serve module is mainly composed of a piezoelectric ceramic transducer, a capacitive displacement sensor, an excitation piezoelectric ceramic ring, and a four-beam spring.

Comparison of the Indentation Processes Using the Single Indenter and Indenter Array: A Molecular Dynamics Study.

Fabrication of periodic nanostructures has drawn increasing interest owing to their applications of such functional structures in optics, biomedical and power generation devices. Nano-indentation technique has been proven as a method to fabricate periodic nanostructures. In this study, the molecular dynamic simulation approach is employed to investigate the nano-indentation process for fabricating periodic nano-pit arrays using a single indenter and an indenter array.

Scanning Probe Lithography: State-of-the-Art and Future Perspectives.

High-throughput and high-accuracy nanofabrication methods are required for the ever-increasing demand for nanoelectronics, high-density data storage devices, nanophotonics, quantum computing, molecular circuitry, and scaffolds in bioengineering used for cell proliferation applications. The scanning probe lithography (SPL) nanofabrication technique is a critical nanofabrication method with great potential to evolve into a disruptive atomic-scale fabrication technology to meet these demands. Through this timely review, we aspire to provide an overview of the SPL fabrication mechanism and the state-the-art research in this area, and detail the applications and characteristics of this technique, including the effects of thermal aspects and chemical aspects, and the influence of electric and magnetic fields in governing the mechanics of the functionalized tip interacting with the substrate during SPL.

The effects of the formation of a multi-scale reinforcing phase on the microstructure evolution and mechanical properties of a TiAlC/TiAl alloy.

In order to acquire TiAl composites with a multi-scale reinforcing phase, and to improve the microstructure and tensile properties at elevated temperatures, TiAl alloys have been prepared with different added carbon content levels via vacuum arc melting. The results show that when the carbon content is greater than or equal to 1.0 at%, then TiAlC forms and the microstructure changes from having a dendrite morphology to an equiaxed crystal morphology.

Molecular Dynamics Study on Tip-Based Nanomachining: A Review.

Tip-based nanomachining (TBN) approaches has proven to be a powerful and feasible technique for fabrication of microstructures. The molecular dynamics (MD) simulation has been widely applied in TBN approach to explore the mechanism which could not be fully revealed by experiments. This paper reviews the recent scientific progress in MD simulation of TBN approach.

A coupled model of electromagnetic and heat on nanosecond-laser ablation of impurity-containing aluminum alloy.

In the emerging field of laser-driven inertial confinement fusion, Joule heating generated electromagnetic heating of the metal frame is a critical issue. However, there are few reported models explaining thermal damage to the aluminum alloy. The aim of this study was to build a coupled model for electromagnetic radiation and heat conversion of an ultrashort laser pulse on an aluminum alloy based on Ohm's law.

Direct Nanomachining on Semiconductor Wafer By Scanning Electrochemical Microscopy.

Scanning electrochemical microscopy (SECM) is one of the most important instrumental methods of modern electrochemistry due to its high spatial and temporal resolution. We introduced SECM into nanomachining by feeding the electrochemical modulations of the tip electrode back to the positioning system, and we demonstrated that SECM is a versatile nanomachining technique on semiconductor wafers using electrochemically induced chemical etching. The removal profile was correlated to the applied tip current when the tip was held stationary and when it was moving slowly (<20 μm s ), and it followed Faraday's law.

Mechanical properties of gold nanowires prepared by nanoskiving approach.

The nanoskiving method based on nanocutting process is a new, low cost and easy way to machine nanowires. In this study, this technique is used to machine Au nanowires with different cutting directions and depths. Young's modulus and the yield strength of nanowires are then measured by an atomic force microscope-based three-point bending test.

Nano/Microscale Thermal Field Distribution: Conducting Thermal Decomposition of Pyrolytic-Type Polymer by Heated AFM Probes.

In relevant investigations and applications of the heated atomic force microscope (AFM) probes, the determination of the actual thermal distribution between the probe and the materials under processing or testing is a core issue. Herein, the polyphthalaldehyde (PPA) film material and AFM imaging of the decomposition structures (pyrolytic region of PPA) were utilized to study the temperature distribution in the nano/microscale air gap between heated tips and materials. Different sizes of pyramid decomposition structures were formed on the surface of PPA film by the heated tip, which was hovering at the initial tip-sample contact with the preset temperature from 190 to 220 °C for a heating duration ranging from 0.

Label-free highly sensitive probe detection with novel hierarchical SERS substrates fabricated by nanoindentation and chemical reaction methods.

Nanostructures have been widely employed in surface-enhanced Raman scattering (SERS) substrates. Recently, in order to obtain a higher enhancement factor at a lower detection limit, hierarchical structures, including nanostructures and nanoparticles, appear to be viable SERS substrate candidates. Here we describe a novel method integrating the nanoindentation process and chemical redox reaction to machine a hierarchical SERS substrate.

Nanofluidic devices prepared by an atomic force microscopy-based single-scratch approach.

Nanofluidic chips with different numbers of nanochannels were fabricated based on a commercial AFM system using a single-scratch approach. The electrical characterization and enzymatic reactions at the nanoscale were demonstrated using the obtained chips. The effects of the number of nanochannels and the solution concentration on the measured electric current were investigated.

Scratch on Polymer Materials Using AFM Tip-Based Approach: A Review.

As a brand new nanomachining method, the tip-based nanomachining/nanoscratching (TBN) method has exhibited a powerful ability at machining on polymer materials and various structures have been achieved using this approach, ranging from the nanodot, nanogroove/channel, bundle to 2D/3D (three-dimensional) nanostructures. The TBN method is widely used due to its high precision, ease of use and low environmental requirements. First, the theoretical models of machining on polymer materials with a given tip using the TBN method are presented.

Three-dimensional paper based platform for automatically running multiple assays in a single step.

Paper based assays are paving the way to automated, simplified, robust and cost-effective point of care testing (POCT). We propose a method for fabricating three dimensional (3D) microfluidic paper based analytical devices (μPADs) via combining thin adhesive films and paper folding, which avoids the use of cellulose powders and the complex folding sequence and simultaneously permits assays in several layers. To demonstrate the effectiveness of this approach, a 3DμPADs was designed to conduct more assays on a small footprint, allowing dual colorimetric and electrochemical detections.

Fabrication of polydimethylsiloxane nanofluidic chips under AFM tip-based nanomilling process.

In current research realm, polydimethylsiloxane (PDMS)-based nanofluidic devices are widely used in medical, chemical, and biological applications. In the present paper, a novel nanomilling technique (consisting of an AFM system and a piezoelectric actuator) was proposed to fabricate nanochannels (with controllable sizes) on PDMS chips, and nanochannel size was controlled by the driving voltage and frequency inputted to the piezoelectric actuator. Moreover, microchannel and nanochannel molds were respectively fabricated by UV lithography and AFM tip-based nanomilling, and finally, PDMS slabs with micro/nanochannels were obtained by transfer process.

A novel AFM-based 5-axis nanoscale machine tool for fabrication of nanostructures on a micro ball.

This paper presents a novel atomic force microscopy (AFM)-based 5-axis nanoscale machine tool developed to fabricate nanostructures on different annuli of the micro ball. Different nanostructures can be obtained by combining the scratching trajectory of the AFM tip with the movement of the high precision air-bearing spindle. The center of the micro ball is aligned to be coincided with the gyration center of the high precision to guarantee the machining process during the rotating of the air-bearing spindle.

Fabrication of gold-coated PDMS surfaces with arrayed triangular micro/nanopyramids for use as SERS substrates.

Using the tip-based continuous indentation process, arrays of three-dimensional pyramidal cavities have been successfully machined on a copper template and the structures were successfully transferred to a polydimethylsiloxane (PDMS) surface using a reverse nanoimprinting approach. The structured PDMS surface is coated with a thin Au film, and the final substrate is demonstrated as a surface-enhanced Raman spectroscopy (SERS) substrate. Rhodamine 6G (R6G) was used as a probe molecule in the present study to confirm the SERS measurements.

Fabrication of Nanoscale Pits with High Throughput on Polymer Thin Film Using AFM Tip-Based Dynamic Plowing Lithography.

We show that an atomic force microscope (AFM) tip-based dynamic plowing lithography (DPL) approach can be used to fabricate nanoscale pits with high throughput. The method relies on scratching with a relatively large speed over a sample surface in tapping mode, which is responsible for the separation distance of adjacent pits. Scratching tests are carried out on a poly(methyl methacrylate) (PMMA) thin film using a diamond-like carbon coating tip.

Chemisorption of hydrogen on graphene: insights from atomistic simulations.

The properties of graphene can be chemically altered by changing its local binding configurations. In the present work, we investigate fundamentals of chemisorption of atomic hydrogen on graphene and its influence on mechanical properties of as-hydrogenated graphene by means of molecular dynamics simulations. Our simulation results indicate that there are diversiform hydrogen-graphene configurations formed in the chemisorption process.