The rise of multidrug-resistant (MDR) bacteria highlights the urgent need for innovative antimicrobial strategies to prevent and control bacterial colonization and biofilm formation. Among these strategies, bactericidal nanostructured surfaces have emerged as promising candidates due to their capability to physically disrupt the bacterial envelope. In this study, the antibacterial efficacy of polymethyl methacrylate (PMMA) surfaces patterned via Electron Beam Lithography (EBL) with nanogratings and nanopillar arrays, arranged in Square (SQ) and Triangular (TR)-tiling geometries, all with a pitch of 210 nm, was investigated. The morphological and nanomechanical responses of Escherichia coli to these nanostructures were evaluated using Atomic Force Microscopy (AFM), Ultra High-Resolution Scanning Electron Microscopy (UHR-SEM), and Focused Ion Beam (FIB) milling. Results reveal that nanopatterned surfaces significantly reduce bacterial adhesion and induce pronounced alterations in cell morphology, including deformation, volume collapse, and membrane rupture. AFM-based force spectroscopy further indicates a decrease in Young’s modulus and an increase in adhesion forces between bacterial cells and the AFM tip, in bacteria exposed to nanopatterned substrates, supporting a mechano-bactericidal mechanism driven by membrane tension and mechanical stress. Importantly, biosafety assays using NIH/3T3 fibroblasts demonstrated preserved cell viability and enhanced spreading on nanopatterned PMMA, confirming cytocompatibility. Together, these findings provide direct experimental evidence of geometry-driven mechanical bacterial inactivation while maintaining mammalian cell compatibility, highlighting the potential of PMMA nanopatterned surfaces for antibacterial coatings in biomedical devices and healthcare environments.

ABSTRACT The rapid growth of miniaturized, high‐performance electronics has created an urgent need for sustainable materials and, consequently, nanofabrication methods that minimize environmental and health impacts. Conventional micro and nanolithography methods rely on toxic materials and energy‐intensive processes, contributing to escalating e‐waste and environmental inequities. To address these challenges, research has increasingly focused on biodegradable polymers and green lithographic techniques as viable alternatives for next‐generation device manufacturing. Here, a sustainable nanofabrication strategy that integrates chitosan‐based biodegradable thin films with Constant Pulse‐Assisted Force Lithography (CP‐AFL) for high‐resolution nanopatterning is presented. Using CP‐AFL, reproducible arrays of nanogrooves with tunable depths, which served as templates for the formation of gold nanowires, were fabricated. This process achieved precise nanoscale control under ambient conditions without the use of toxic chemicals, high‐energy radiation, or advanced instrumentation. These results demonstrate the potential of combining biopolymer resists with low‐energy, low‐toxic solvent processes to advance eco‐friendly micro‐ and nanomanufacturing. By providing an environmentally benign pathway for device fabrication, this work moves the field closer to sustainable electronics suitable for applications in flexible, biomedical, and transient devices.

The growing request for more sustainable materials and environmentally friendly nanofabrication methods in the electronics field has recently driven the scientific community in the development of bio-derived materials as an alternative to conventional lithographic resists. In this work, we used chitosan, a biodegradable and biocompatible polysaccharide, as a green direct-write resist material for Atomic Force Microscopy-based nanolithography. Chitosan thin layers were obtained by spin coating and systematically characterized, in terms of thickness and surface roughness, demonstrating nanoscale smoothness and tunable film thickness. Three Pulse-Atomic Force Lithography (P-AFL) approaches, i.e., Constant Pulse, Gradient Pulse, and Raster Pulse AFL methods, were used to pattern nanostructures with constant-depth nanogrooves, variable-depth (2.5D) profile, and three-dimensional nanoholes on chitosan films. The results reveal high pattern fidelity, reproducibility, and tunability of feature dimensions as a function of applied force and scanning direction. Moreover, the RP-AFL technique enabled the fabrication of well-defined 3D nanostructures with depths matching the film thickness, which is a prerequisite for subsequent pattern transfer. This experimental work provided a first proof-of-concept to adopt chitosan as a more sustainable alternative with respect to conventional resists. Moreover, the results highlight P-AFL methods as a versatile and low-impact nanofabrication strategy, contributing to the development of greener micro- and nano-manufacturing technologies.

The rapid advancement of nanoscience and nanotechnology stimulated the demand for high-resolution, scalable, and versatile fabrication techniques. Among the emerging strategies, atomic force microscope-based mechanical scanning probe lithography has evolved into a powerful platform for nanoscale patterning. This review presents a comprehensive overview of recent progress in m-SPL, emphasizing both fundamental mechanisms and applied methodologies. Key approaches, including nanoindentation, Pulse-AFM lithography, Static and Dynamic Plowing Lithography, thermal- and bias-assisted methods, and vibration-assisted strategies, are critically analyzed with respect to their patterning resolution, process controllability, and material compatibility. Particular attention is given to the integration of external stimuli, such as electric fields, thermal excitation, and ultrasonic or elliptical vibrations, which expand the fabrication capability and enhance reproducibility. Case studies illustrate applications across metallic films, semiconductors, polymers, and two-dimensional materials, highlighting advances in plasmonics, sensing, electronics, and quantum devices. Mechanistic insights derived from experimental studies and molecular dynamics simulations are also summarized, providing guidance for optimizing process parameters and mitigating subsurface damage. Taken together, m-SPL emerges not only as a complementary approach to conventional lithographic methods but also as a transformative nanomanufacturing technology with the potential to bridge the gap between laboratory-scale prototyping and scalable device integration.

Nanostructured antibacterial surfaces have recently gained significant interest for their ability to mechanically disrupt bacterial cells and reduce populations. This study presents an efficient method for fabricating PMMA nanostructures using Electron Beam Lithography, focusing on nanograting and nanopillar arrays with pitches ranging from 160 to 200 nm. Atomic Force Microscopy was employed to characterize these structures. The antibacterial efficacy was assessed against Escherichia coli revealing a significant reduction in bacterial adhesion, grown on the nanostructures compared to the flat PMMA surfaces, with the nanopillars showing a more pronounced effect (about 85 %) compared to the nanogratings (75 %). The bacteria exhibited significant shape changes and damage, indicative of severe cellular disruption. Detailed AFM analysis confirmed notable morphological changes, including reduced major axis length, decreased surface area, and increased roughness, probably due to membrane rupture. Nanomechanical studies on the cell surface revealed changes in E. coli Young's modulus and adhesion forces, further demonstrating that nanostructures play a role. The Young's modulus of E.coli changes from (1.5 f 0.2) MPa on flat PMMA (control) to (0.7 f 0.1) MPa on nanograting with a pitch of 160 nm (lower pitch) and (0.5 f 0.1) MPa on nanopillars with a pitch of 200 nm (higher pitch). Similarly, the adhesion forces of bacteria grown on flat PMMA were (1.8 f 0.1) nN while they increased to (7.2 f 0.1) nN and (14.8 f 1.4) nN for lower-pitch nanogratings and higher-pitch nanopillars, respectively. These findings highlight the potential of nanostructured surfaces as advanced antibacterial materials.

The rapid advancement of nanoscience has driven significant interest in manipulating materials at the nanoscale, a capability critical to diverse High-tech fields. Achievements in nanoscale analysis and nanofabrication have facilitated practical applications across a range of fields, including nanoelectronics, nanofluidics, drug delivery, optical and plasmonic devices, and biosensing. Nonetheless, conventional top-down fabrication techniques, such as electron beam lithography, focused ion beam lithography, soft lithography, and nanoimprint lithography, are frequently constrained by factors such as cost, scalability, and manufacturing complexity. Scanning Probe-based Lithography (SPL) has recently emerged as a promising alternative, offering precise nanostructure fabrication and immediate characterization in ambient conditions. This paper focuses on Raster-Atomic Force nanolithography (R-AFL), highlighting its capability for fabricating 3D nanostructures on Polymethyl methacrylate (PMMA) with minimal process steps. By coupling this technique with a simple wet etching process using Methyl Isobutyl Ketone (MIBK) and 2-propanol (IPA), enhanced resolution and quality of the nanostructure are achieved. Furthermore, the nanostructures are successfully transferred to a Silicon Nitride (SixNy) substrate via plasma etching, demonstrating the versatility of the approach. This combination of AFM-based lithography, wet etching, and plasma transfer represents an innovative and efficient method for creating nanopatterned surfaces on both soft and hard substrates, addressing key limitations of conventional nanofabrication techniques.

The rapid growth of miniaturized, high-performance electronics has created an urgent need for sustainable materials and, consequently, nanofabrication methods that minimize environmental and health impacts. Conventional micro and nanolithography methods rely on toxic materials and energy-intensive processes, contributing to escalating e-waste and environmental inequities. To address these challenges, research has increasingly focused on biodegradable polymers and green lithographic techniques as viable alternatives for next-generation device manufacturing. Here, a fully sustainable nanofabrication strategy that integrates chitosan-based biodegradable thin films with Constant Pulse-Assisted Force Lithography (CP-AFL) for high-resolution nanopatterning is presented. Using CP-AFL, reproducible arrays of nanogrooves with tunable depths, which served as templates for the formation of gold nanowires, were fabricated. This process achieved precise nanoscale control under ambient conditions without the use of toxic chemicals, high-energy radiation, or advanced instrumentation. These results demonstrate the potential of combining biopolymer resists with low-energy, solvent-free lithography to advance eco-friendly micro- and nanomanufacturing. By providing a scalable, industrially compatible, and environmentally benign pathway for device fabrication, this work moves the field closer to sustainable electronics suitable for applications in flexible, biomedical, and transient devices.

Ultra-high-speed photonic devices covering O- and C-bands (1260-1565 nm) are in great demand for datacom and telecom applications, and are almost exclusively produced on InP substrates due to its bandgap, and high carrier mobility. Addition of small amounts of Nitrogen to III-V compounds, known as dilute nitride (DN) technology, modifies the bandgap, but results in high effective masses, making it unsuitable for transit-time dependent devices such as transistors, PIN and metal-semiconductor-metal photodetectors (MSM-PD's). A family of devices is produced that circumvent these limitations by incorporating doped heterojunctions that decrease the dark current, produce reservoir(s) of confined two-dimensional electron gas (2DEG), and landscape the electric field. Consequently, optically generated electrons navigate a thin absorption region to reach the 2DEG, causing current in external circuitry without arriving at anode. These 2DEG-DNMSM's have low dark current (<1.0 nA), and the fastest reported DN response speed with rise time of 11 ps, fall time of 28 ps, and pulse-width of 14 ps; a speed which remains the same even when cathode-anode distance increases by 3x. These opto-plasmonic InGaAs:N devices, fabricated on GaAs using standard processes compete favorably, at fraction of the cost, with InGaAs on InP devices which have > 60x higher electron mobility.

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.

Electrostatically actuated microelectromechanical system (MEMS) switches with fixedfixed beams were fabricated.FEM modeling was used to calculate the contributions of stress in the fabricated beams from the measured values of pull-in voltage.The reported study provides useful guidelines to optimize the design of fixed-fixed beams, in order to reduce the stress contributions for the successful development of efficient and reliable electrostatically actuated MEMS devices.

The increasing use of nanomaterials in high-tech devices has posed an exciting challenge for the scientific community to develop new, easy, high-throughput nanofabrication approaches. Here, we present an easy AFM-based nanofabrication approach based on Static Plowing Lithography, with which we are able to realize patterns of 3D nanostructures on a thin PMMA layer. By coupling a wet etching process with ultrasound exposure, we effectively removed the polymer bulges at the nanostructure's borders, increasing the quality of the patterned 3D nanostructures, and paving the way for their integration into lab-on-a-chip devices.

In this work, a low-temperature fabrication process of thin-film encapsulation (TFE) with silicon nitride/chromium cap is proposed for large-size ( $750\times 300\,\,\mu \text{m}$ ) packaging of microelectromechanical systems (MEMS). A finite element method (FEM) model was developed to evaluate the shape of TFE as a function of the residual stress and the thickness of the sealing layer, providing useful guidelines for the fabrication process. The low temperature of 200 °C, which was used in the plasma-enhanced chemical vapor deposition (PECVD) of the silicon nitride capping layer, allowed an organic sacrificial material to be employed for the definition of the encapsulation area. Silicon nitride/chromium ( $1 \mu \text{m}$ /20 nm) bilayer was demonstrated to be successful to overcome the technological limitations that affect the creation of cap holes with size of $\sim 2 \mu \text{m}$ on high-topography substrates, as in the case of MEMS. Plasma focused ion beam (PFIB) and scanning electron microscopy (SEM) techniques were used in combination to gain deeper insight into the sealing process of cap holes. Specifically, a PFIB–SEM serial Section procedure was developed, resulting to be a powerful tool to directly observe the sealing profile above cap holes. Hence, the presented results greatly contribute to overcome the main technological/reliability issues of TFE, paving the way for the widespread application of the proposed encapsulation methodology to the most used MEMS devices, such as radio frequency (RF) switches, transducers, actuators, sensors, and resonators.

Sputtered aluminum nitride (AlN) thin films were characterized by Piezoresponse Force Microscopy (PFM) technique using a methodology to decrease the contribution of the electrostatic forces to obtain a pure piezoelectric response. Our method is based on the sweeping of the DC voltage applied to the Atomic Force Microscope (AFM) tip under a fixed AC field to evaluate the contact surface potential difference (VCPD) between the tip and the sample used to measure the proper AlN piezoelectric coefficient (d33,eff), minimizing the electrostatic contribution. Kelvin probe Force Microscopy (KPFM) was employed as reference standard technique to measure the surface potential, confirming the reliability of the proposed experimental procedure on ceramic piezoelectric films, and simultaneously overcoming the disadvantages of the KPFM technique. The capability to tune surface potential of materials over a wide range of values opens new perspectives for the design of devices with changeable surface potential.

High-speed photodetectors’ intrinsic response is limited by the transit time of the carriers that light generates to the contacts that collect these carriers generating an electric response in the external circuitry. By contrast, charge plasma confined in a semiconductor can transfer energy, hence responding much faster, than the field-induced carrier drifts current. The analogy is to a drop exciting a wave in a reservoir, which is detected more rapidly than the drop’s transport by current flow. Here we construct a photodetector device in which charge reservoirs of confined two-dimensional electron and hole gasses (2DEG, 2DHG) mediate the photodetector response circumventing charge transport limitations in both expended energy and required velocity. In response to short optical pulses, this device produces electrical pulses which are almost two orders of magnitude shorter than the same device without the charge reservoirs. In addition to speed, the sensitivity of this process allows us to measure, at room temperature, as low as 11,000 photons. The device is shown to operate without applied bias, with high responsivity, at hundreds of gigahertz. These microplasma devices can have a range of applications such as optical communication with a fraction of a microwatt power compared to the present tens of milliwatts, ultrasensitive detection of light without the need for cryogenic cooling, photovoltaic devices that are capable of harvesting dim light, detectors of THz radiation, and in the detection of charged particles.

The synergistic effect of silicon-based substrates on the physical and chemical properties of aluminum nitride (AlN) thin films was investigated. AlN thin films were deposited by RF magnetron sputtering on Low Resistivity (LR) Si, Silicon On Insulator (SOI) and Si/SiO2 substrates at room temperature. The morphological and structural properties were investigated by X-ray diffraction (XRD), Raman spectroscopy, Atomic Force microscopy (AFM). XRD analyses evidenced the co-presence of (002) and (101) orientations. The substrate influence on films morphology, crystalline order, intrinsic stress and grain size is well evidenced, as shown by Raman and AFM analyses. These surface characterization techniques represent a valid support to select the suitable Si-substrate/ piezoelectric thin film combination for the fabrication of a piezoelectric device. AlN sputtered on Si-LR substrate showed an enhancement of structural arrangement along (002) planes while the sample sputtered on Si/SiO2 resulted mainly oriented along (101) planes. For these reasons, further characterization was done: (002) -ori-ented AlN thin films were characterized in terms of piezoelectric response by piezometer and Piezoresponse Force Microscopy (PFM) measurements, while cytotoxicity and biocompatibility were investigated for (1 01) -oriented AlN thin films. This further investigation helped to assess the suitable film to integrate into piezoelectric devices operating in air or in liquid, respectively.

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.

In recent decades, great efforts have been made to develop innovative, effective, and accurate nanofabrication techniques stimulated by the growing demand for nanostructures. Nowadays, mechanical tip-based emerged as the most promising nanolithography technique, allowing the pattern of nanostructures with a sub-nanometer resolution, high reproducibility, and accuracy. Unfortunately, these nanostructures result in contoured pile-ups that could limit their use and future integration into high-tech devices. The removal of pile-ups is still an open challenge. In this perspective, two different AFM-based approaches, i.e., Force Modulation Mode imaging and force-distance curve analysis, were used to characterize the structure of pile-ups at the edges of nanogrooves patterned on PMMA substrate by means of Pulse-Atomic Force Lithography. Our experimental results showed that the material in pile-ups was less stiff than the pristine polymer. Based on this evidence, we have developed an effective strategy to easily remove pile-ups, preserving the shape and the morphology of nanostructures.

Wearable tactile technology in the configuration of actuated thimbles is used to provide the sense of touch in virtual (VR) and augmented reality (AR) and teleoperation contexts. The design of these types of devices includes specific purposes: limiting the overall dimensions of the system to enhance the wearability and increasing the effectiveness and naturalness of the stimulation. This new generation of wearable touch systems can transmit tactile signals more naturally, whilst also being comfortably worn by the user, portable and integrated in daily life. In this direction, we propose a haptic device based on electro-cutaneous feedback to selectively stimulate each mechanoreceptor to discriminate specific tactile sensations. Two important features characterize and make our device innovative: wearability and ease of use. The first feature is enhanced by a flexible holder made of a combination of polydimethylsiloxane (PDMS) and Kapton layers, that allows the device to be wrapped around the fingertip to provide stimulation in the area with higher density of mechanoreceptors and make possible to place the system ground close to the stimulus application point. A more complex stimulation enhances increasingly accurate tactile sensations, so the guidelines of our research were focused on the enrichment of parameters variety that define each stimulation (frequency, waveform, duty cycle, current intensity, anodic/cathodic configuration, and dynamic stimulation) by the development of a functional electronics board (4 h of autonomy per battery discharge cycle). The second feature uses the Bluetooth Low Energy (BLE) protocol to connect the electronic board of the device to a common smartphone, which allows user to manage the stimulation through a specific Android application allowing intelligent and integrated control of the haptic microsystem. Our haptic device is lightweight, does not affect normal hand movement, portable and easy to manage via your smartphone; this makes it available to a large scale of people.