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In recent years, Atomic Force Microscope (AFM)-based nanolithography techniques have emerged as a very powerful approach for the machining of countless types of nanostructures. However, the conventional AFM-based nanolithography methods suffer from low efficiency, low rate of patterning, and high complexity of execution. In this frame, we first developed an easy and effective nanopatterning technique, termed Pulse-Atomic Force Lithography (P-AFL), with which we were able to pattern 2.5D nanogrooves on a thin polymer layer. Indeed, for the first time, we patterned nanogrooves with either constant or varying depth profiles, with sub-nanometre resolution, high accuracy, and reproducibility. In this paper, we present the results on the investigation of the effects of P-AFL parameters on 2.5D nanostructures' morphology. We considered three main P-AFL parameters, i.e., the pulse's amplitude (setpoint), the pulses' width, and the distance between the following indentations (step), and we patterned arrays of grooves after a precise and well-established variation of the aforementioned parameters. Optimizing the nanolithography process, in terms of patterning time and nanostructures quality, we realized unconventional shape nanostructures with high accuracy and fidelity. Finally, a scanning electron microscope was used to confirm that P-AFL does not induce any damage on AFM tips used to pattern the nanostructures. [ABSTRACT FROM AUTHOR]

Natural halloysite clay nanotubes (HNTs) are versatile inorganic reinforcing materials for creating hybrid composites. Upon doping HNTs with polymers, coating, or loading them with bioactive molecules, the production of novel nanocomposites is possible, having specific features for several applications. To investigate HNTs composites nanostructures, AFM is a very powerful tool since it allows for performing nano-topographic and morpho-mechanical measurements in any environment (air or liquid) without treatment of samples, like electron microscopes require. In this review, we aimed to provide an overview of recent AFM investigations of HNTs and HNT nanocomposites for unveiling hidden characteristics inside them envisaging future perspectives for AFM as a smart device in nanomaterials characterization. [ABSTRACT FROM AUTHOR]

The widespread use of nanotechnology in different application fields, resulting in the integration of nanostructures in a plethora of devices, has addressed the research toward novel and easy-to-setup nanofabrication techniques to realize nanostructures with high spatial resolution and reproducibility. Owing to countless applications in molecular electronics, data storage, nanoelectromechanical, and systems for the Internet of Things, in recent decades, the scientific community has focused on developing methods suitable for nanopattern polymers. To this purpose, Atomic Force Microscopy-based nanolithographic techniques are effective methods that are relatively less complex and inexpensive than equally resolute and accurate techniques, such as Electron Beam lithography and Focused Ion Beam lithography. In this work, we propose an evolution of nanoindentation, named Pulse-Atomic Force Microscopy, to obtain continuous structures with a controlled depth profile, either constant or variable, on a polymer layer. Due to the modulation of the characteristics of voltage pulses fed to the AFM piezo-scanner and distance between nanoindentations, it was possible to indent sample surface with high spatial control and fabricate highly resolved 2.5D nanogrooves. That is the real strength of the proposed technique, as no other technique can achieve similar results in tailor-made graded nanogrooves without the need for additional manufacturing steps. [ABSTRACT FROM AUTHOR]

[Display omitted] • m-SPL techniques allow the patterning at the nanoscale with unprecedented precision. • Nanoindentation is the easiest m-SPL, permitting the realization of nanoholes array. • AFM Plowing lithographies allow for patterning in contact and semicontact modes. • Static and Dynamic Plowing lithography stands for advanced m-SPL techniques. • Coupled m-SPL enhances the patterning capability and the properties of nanostructures. In recent years, the scientific community's interest in nanoscience and nanotechnology stems from the increasing capability to manipulate matter at the nanoscale. Nanotechnology development is closely linked to fabricating and characterizing structures below 100 nm, driven by technological advancements enabling their in-depth analysis. Up to now, several top-down and bottom-up nanofabrication approaches have been developed to realize a plethora of nanostructures. Although effective, these methods have many drawbacks like high costs and limitations in feature size. In this scenario, Scanning Probe-based Lithography (SPL) emerges as a very promising alternative to conventional nanofabrication techniques, overcoming their main method limitations with versatility, flexibility, low cost, and nanoscale resolution. This review focuses on mechanical Scanning Probe-based Lithography (m-SPL), tracing its evolution from inception to recent advances. Different m-SPL methods, such as Nanoindentation, Static and Dynamic Plowing lithography, Nanomilling, and their variants are discussed in-depth, emphasizing their advantages and drawbacks, and highlighting their application. Moreover, this review explores the effects of combining m-SPL with other energy sources, such as heat and electric energy, and outlines future perspectives in the field. Overall, m-SPL stands out as a promising avenue in nanofabrication, offering sub-nanometer resolution and diverse material manipulation capabilities. [ABSTRACT FROM AUTHOR]