Free-standing State Research Articles

Tailoring Ge membrane adhesion strength: Impact of growth parameters and porous layer thickness

The recent exploration of porous Germanium (PGe) techniques marks a significant advancement in the scalable production of detachable Ge membranes and devices. However, there is a notable gap in the comprehensive understanding of the critical factors necessary to control the adhesion strength of these nanomembranes. This study delves into the effects of Ge growth temperature, in-situ annealing processes, and the thickness of the PGe layer on the reorganization of the porous interlayer, subsequently influencing the properties of the separation layer. We particularly focus on how adjusting these parameters can fine-tune the adhesion strength of the epitaxial layer, ranging from a freestanding state to a fully bonded nanomembrane. A key finding is that the thermal budget experienced by the porous structure during the buffer layer's growth significantly affects the nanomembrane's adhesion characteristics; it is imperative to minimize this duration, especially at higher growth temperatures. Our research demonstrates that by precisely controlling the voids within the PGe layer, the adhesion strength can be effectively modulated through variations in the PGe layer's thickness. The outcomes of this study offer crucial insights into the controllable adhesion strength of Ge nanomembranes, paving the way for the targeted development of detachable devices.

Stabilizing Phosphorene‐Like Group IV–VI Compounds via van der Waals Imprinting for Multistate Ferroelectricity and Tunable Spin Transport

AbstractLayered group IV–VI compounds (i.e., SnSe, SnS, GeSe, and GeS) in the puckered structure resembling black‐phosphorene (BlackP) have attracted increasing interest because of their intriguing ferroic orders and outstanding thermoelectric properties. By invoking the guiding principles of isovalency and isomorphism for promoting van der Waals epitaxy, and based on comprehensive first‐principles calculations, here it is shown that the typically metastable BlackP‐like GeTe can be readily stabilized on the (001) surface of isostructural SnSe. Importantly, the ferroelectricity of such a BlackP‐like GeTe monolayer can be substantially enhanced compared to the freestanding state, due to the substrate enlarged in‐plane polar displacements. The GeTe/SnSe heterobilayer exhibits multiple ferroelectric/ferrielectric polarization states, which can be exploited for high‐density memory devices. These mutually switchable polarization states are also shown to be internally locked with the spin polarization of the valence/conduction bands with pronounced Rashba spin‐orbit splitting and Berry curvature dipole. These findings highlight the intuitive yet enabling power of van der Waals imprinting in growing novel 2D materials for enriched functionalities.

Aperiodic Modulation of Graphene Driven by Oxygen-Induced Reconstruction of Rh(110).

Artificial nanostructuring of graphene has served as a platform to induce variations in its structural and electronic properties, fostering the experimental observation of a wide and fascinating phenomenology. Here, we present an approach to graphene tuning, based on Rh(110) surface reconstruction induced by oxygen atoms intercalation. The resulting nanostructured graphene has been characterized by scanning tunneling microscopy (STM) complemented by low-energy electron microscopy (LEEM), micro low-energy electron diffraction (μ-LEED), micro angle-resolved photoemission spectroscopy (μ-ARPES), and micro X-ray photoelectron spectroscopy (μ-XPS) measurements under ultrahigh vacuum (UHV) conditions at room temperature (RT). It is found that by fine-tuning the O2 exposure amount, a mixture of missing row surface reconstructions of the metal surface below the graphene layer can be induced. This atomic rearrangement under the graphene layer results in aperiodic patterning of the two-dimensional (2D) material. The electronic structure of the resulting nanostructured graphene is dominated by a linear dispersion of the Dirac quasiparticles, characteristic of its free-standing state but with a p-doping character. The local effects of the underlying missing rows on the interfacial chemistry and on the quasiparticle scattering processes in graphene are studied using atomically resolved STM images. The possibilities offered by this nanostructuring approach, which consists in inducing surface reconstructions under graphene, could provide a novel tuning strategy for this 2D material.

Facile physical modification of ultrathin polyethylene by trace poly(vinyl alcohol)

Poly (vinyl alcohol) (PVA) modification to nonpolar polymers has been intensively investigated due to the performance improvement in membrane separation, tissue engineering, and other applications. Slightly deviated from the conventional route, no covalent bonding by crosslinking or hydrogen bonding is needed to anchor PVA onto the target matrix. This work harnessed van der Waals interaction only to achieve the modification. Owing to the high surface energy and aspect ratio of ultra-high molecular weight polyethylene (UHMWPE) ultrathin membranes, the physical binding between PVA and PE was found stable and easy to establish. This interaction is initiated by the entropy-driven hydrophobic effect at the liquid-solid interface to reduce surface energy. By encapsulation of PVA on the fibrils, the PE hydrophilicity could be overturned (from 134.6° to 48.4°) with micro-structures remaining almost intact at the low loading of modification (0.001% conc. solution dip-coating). The resultant hydrophilic ultrathin PVA-PE membranes showed high transparency, high mechanical strength (380 MPa in tensile max. stress), and high porosity with only 200 nm thickness in a freestanding state. This work provides a facile approach to switch the hydrophilicity of nonpolar polymer ultrathin membranes by establishing vdW physical bonding only. By trace-adsorption, this method could also be helpful in fine-tuning nanostructures of the target polymer matrix by a resolution of nanometer level.

Theoretical insights into the epitaxial growth of black arsenene enabled on GeS(001)

Black arsenene exhibits many exotic physical properties, such as Rashba spin–orbital coupling, fractional quantum Hall effect (Sheng 2021 Nature 593 56) as well as some advantages in the field of energy storage (Wu et al 2021 J. Mater. Chem. A 9 18793). High-quality and large-area BA monolayer can promote the investigations about BA and its device application. Epitaxial growth mechanism of BA is desirable. Here, based on density functional theory calculation, the epitaxial growth of BA monolayer was simulated. GeS(001) is found to be a suitable substrate for BA monolayer to epitaxially grow on. As a common isomer of arsenene, gray arsenene should be considered during the growth, because it is also energetically and thermodynamically stable in freestanding state. However, black arsenene monolayer is more energetically and thermodynamically stable than gray arsenene monolayer on GeS(001) substrate. During the growth, two arsenene atoms easily form a dimer on GeS(001), which diffuses more quickly and isotropically than arsenene monomer. In addition, the heterojunction consisted of balck arsenene and GeS(001) is an indirect gap semiconductor, but it can transform into a direct gap semiconductor with external tensile strain along zigzag direction. Remarkably, optical adsorption spectra range of BA/GeS(001) can be more abroad than that of BA and GeS(001) bilayers. The theatrical insights shed new light on some ideal substrates that can realize the epitaxial growth of high-quality simple substances of group V.

The Soft Ray-Inspired Robots Actuated by Solid-Liquid Interpenetrating Silicone-Based Dielectric Elastomer Actuator.

Dielectric elastomer actuators (DEAs) are widely used in robotics and artificial muscles because of their large energy densities and short response time. In this study, we developed two types of soft ray-inspired robots using solid-liquid interpenetrating silicone-based DEAs, named SIS DEAs. The optimized SIS DEA had an actuation strain of 79.8% at 20.43 kV/mm in a freestanding state, which was used as the muscle of the ray robot. To imitate the swimming behavior of the ray, the effect of the driving frequency on the velocity of the ray robot was explored. The ray robot achieved a maximum swimming rate of 5.7 mm/s when the driving frequency was ∼0.6 Hz. In addition, the steady-state and the transient simulation were carried out to reveal the mechanism of the ray robot's electro-swimming. The results revealed that the actuating deformation of the SIS DEAs caused the electro-deformation of the ray robot, and the periodical electro-deformation generated the high-speed vortex beneath the robot to push the ray robot forward. The high actuation strain in the freestanding state and the shape customizability of the SIS DEAs made it an ideal alternative to muscles for various soft robots.

Accurate determination of electrical conductance in carbon nanostructures

Electrical characterization of nanostructures, such as nanotubes and wires, is a demanding task that is vital for future applications of nanomaterials. The nanostructures should ideally be analyzed in a free-standing state and also allow for other material characterizations to be made of the same individual nanostructures. Several methods have been used for electrical characterizations of carbon nanotubes in the past. The results are widely spread, both between different characterizations methods and within the same materials. This raises questions regarding the reliability of different methods and their accuracy, and there is a need for a measurement standard and classification scheme for carbon nanotube materials. Here we examine a two-probe method performed inside a transmission electron microscope in detail, addressing specifically the accuracy by which the electrical conductivity of individual carbon nanotubes can be determined. We show that two-probe methods can be very reliable using a suitable thermal cleaning method of the contact points. The linear resistance of the outermost nanotube wall can thus be accurately determined even for the highest crystallinity materials, where the linear resistance is only a few kΩ/μm. The method can thereby by used as a valuable tool for future classification schemes of various nanotube material classes.

Electrical characterization of freestanding complex oxide ferroelectrics: Artifacts and experimental precautions

Recently, freestanding complex oxide ferroelectric materials have gained attention due to their tremendous potential in electronic and mechanical engineering applications. Whether these materials in a freestanding form exhibit intrinsically different behavior than in a strongly bonded as-grown state is a topic of ongoing exploration. Several factors such as circuit configuration, substrates, and electronic measurement conditions can affect probing the intrinsic properties of these materials and complicate the conclusive outcome of such exploration. The importance of maintaining the same experimental conditions for a comparative study of these materials in as-grown and freestanding states is discussed here.

Shape memory effect in metallic glasses

Shape memory effect in metallic glasses

Freestanding Ferroelectric Bubble Domains.

Bubble-like domains, typically a precursor to the electrical skyrmions, arise in ultrathin complex oxide ferroelectric-dielectric-ferroelectric heterostructures epitaxially clamped with flat substrates. Here, it is reported that these specially ordered electric dipoles can also be retained in a freestanding state despite the presence of inhomogeneously distributed structural ripples. By probing local piezo and capacitive responses and using atomistic simulations, this study analyzes these ripples, sheds light on how the bubbles are stabilized in the modified electromechanical energy landscape, and discusses the difference in morphology between bubbles in freestanding and as-grown states. These results are anticipated to be the starting point of a new paradigm for the exploration of electric skyrmions with arbitrary boundaries and physically flexible topological orders in ferroelectric curvilinear space.

Exchange bias in flexible freestanding La0.7Sr0.3MnO3/BiFeO3 membranes

Exchange bias lies in the core of cutting-edge technologies, for instance, high-density data storage, spin valves, and high-frequency magnetic devices. As the devices with flexibility have become vital in the forefront of technology, the maintenance of exchange bias under high flexion is highly desired. This paper reports the strong exchange bias in flexible freestanding La0.7Sr0.3MnO3/BiFeO3 membranes with decent mechanical durability. The La0.7Sr0.3MnO3 layer is biased strongly by the BiFeO3 layer even in the freestanding state. At the same time, the strain is demonstrated to affect the strength of the exchange bias of the La0.7Sr0.3MnO3/BiFeO3 bilayer. Furthermore, the saturation magnetization and exchange bias field of the freestanding La0.7Sr0.3MnO3/BiFeO3 membranes are preserved well after 1000 bending cycles. Our work on freestanding membranes paves the way for manufacturing advanced flexible spintronic devices.

A Bio-Conjugation Chemistry Strategy to Self-Immobilize Antibodies with ZIF-90-ZnO-MoS2 Nanohybrid for Exosome Markers Analysis

Motivation Cell signaling proteins have been widely regarded as some of the most powerful biomarkers for cancer diagnosis because they are real therapy related molecules. Extracellular vesicles, exosomes, transport proteins to promote tumor growth and are stable in biofluids at room temperature.[1] Hence, detection of exosomal proteins (e.g., cluster of differentiation (CD) 9, CD 63, CD 81) would be easily deployed at the point-of-care (POC) diagnostic. A successful electrochemical biosensor is generally determined by electrodes and their modification as well as specific bio-recognition elements (BREs).Graphene like MoS2 has emerged in biosensing applications owing to their intriguing properties, such as good catalytic properties, interesting metallic-to-semiconducting transition from 1T to 2H phase, and good biocompatibility.[2] However, a particularly vexing problem for MoS2 as the sensing materials is the structural instability that the exfoliated or ultrathin two dimensional (2D) MoS2 is hard to be retained in in their freestanding state. The surface modification technologies, such as growth of building blocks could transfer the 2D to relatively stable 3D nanoarchitectures, in which each component can also exert different function.Herein, we demonstrate a nanostructure consisting of zinc oxide (ZnO) nanowires (NWs) array grown on 2D MoS2forming a new nanoarchitecture (ZnO-MoS2) providing high specific surface area and good electron transport capability. Then, zeolitic imidazolate framework 90 (ZIF-90) thin films are in-situ deposited onto ZnO NWs by using ZnO as precursor to directly react with imidazole-2-carboxyaldehyde (ICA). The integrated hybrid nanostructure, denoted as ZIF-90-ZnO-MoS2, possesses not only effective mass transport and electron transduction capabilities but also covalent bio-conjugation of BREs through the aldehyde group on the bridging ICA ligand in ZIF-90. Of particular note is the ZnO NWs array is an indispensable part of the hybrid nanostructure, since the in-situ growth of ZIF-90 and effective integration with layered MoS2 is still a challenge. Through the cooperation of three different kinds of building blocks, from signal generation, amplification to transduction could be achieved in an integrated nanoarchecture. Results and Discussion Figure 1a displays the scanning electron microscope (SEM) image of obtained ZIF-90-ZnO-MoS2 nanohybrid, from which the ordered NWs array is uniformly grown onto 2D MoS2 material. The higher magnification SEM (Figure 1b) and transmission electron microscopy (TEM) (Figure 1c) images show that the length and diameter of vertical ZnO NWs are 1.5 μm and 50 nm, respectively. Further high resolution TEM (HR-TEM) (Figure 1d) characterization demonstrates that the NWs are consisted of highly crystal ZnO core with the diameter of about 25 nm and ZIF-90 sheath with the thickness of about 12 nm.A FITC-labeled goat anti-human immunoglobulin G (IgG) is employed to verify our hypothesis. The inset of Figure 1e shows the fluorescence microscopy image of microelectrode immobilized with FITC-labeled goat anti-human IgG. It can be seen that only the region deposited with ZIF-90-ZnO-MoS2 nanohybrid visualizes green fluorescence. This result illustrates ZIF-90-ZnO-MoS2 nanohybrid possesses the capability of direct covalent bio-conjugation of antibody. And the results shown Figure 1e further confirm the developed hybrid material could effectively detect signaling protein.We next fabricated a microfluidic electrochemical microsensor chip, and the configuration is shown in Figure 1f. The microsensor chip is composed of a polydimethylsiloxane (PDMS) layer sealed with screen-printed electrodes. The microsensor is consisted of five electrodes, including counter electrode (CE), reference electrode (RE) and three different working electrodes. Among the three working electrodes, electrode 1 and 2 are locally deposited with fabricated ZIF-90-ZnO-MoS2 nanohybrid material as the test electrodes, and electrode 3 is printed with carbon conductive ink for the background signal deduction. The micro-channels on the chip are employed for the simultaneous immobilization of bio-recognition antibodies as well as dual detection of exosome markers (CD63 and CD9). From Figure 1g, our fabricated microsensor chip shows obvious response towards NCI-H 1650, and almost no signal for other cells supernatant (NCI-H 1650: human non-small cell lung cancer cells, 16 HBE: human bronchial epithelial cells, HFL-1: human fetal lung fibroblast-1 and HUVEC: human umbilical vein endothelial cells). Conclusion In summary, the ZIF-90-ZnO-MoS2 nanohybrid integrated with different kinds of building blocks realizes the cooperation of multi-function, including covalent bio-conjugation of antibodies, signal generation and transduction. To further combine with microfluidic electrochemical microsensor chip, the simultaneous immobilization of bio-recognition antibodies and dual detection of exosome markers can also be acquired.

Modulating electronic structure of graphene overlayers through electrochemical intercalation

Modulating electronic structure of graphene overlayers is highly demanding for its potential applications in microelectronics, sensors, and catalysis, which however remains a grand challenge. Here, we report electrochemistry-involved treatments to tune the electronic structure of graphene overlayers. Both galvanic corrosion and potential-aided intercalation of H2O were employed to change the graphene/Cu interfaces to graphene/Cu2O/Cu and graphene/H2O/Cu interfaces, respectively. Electronic properties and structural changes of the graphene/Cu interfaces were investigated by X-ray photoelectron spectroscopy, in-situ Raman, and atomic force microscopy. The formed Cu2O interlayer blocks the charge transfer between graphene overlayer and Cu substrate, which turns n-type doping of the as-grown graphene to free-standing state. In contrast, the intercalated H2O interlayer induces much stronger n-type doping in graphene through the electrostatic field effect generated by confined H2O. This work offers efficient but mild methods to modulate the doping state of graphene layers.

Self-Healing Electrode with High Electrical Conductivity and Mechanical Strength for Artificial Electronic Skin.

A self-healing electrode is an electrical conductor that can repair internal damage by itself, similar to human skin. Since self-healing electrodes are based on polymers and hydrogels, these components are still limited by low electrical conductivity and mechanical strength. In this study, we designed an electrically conductive, mechanically strong, and printable self-healing electrode using liquid crystal graphene oxide (LCGO) and silver nanowires (AgNWs). The conductive ink was easily prepared by simply mixing LCGO and AgNWs solutions. The ultrathin (3 μm thick) electrode can be printed in various shapes, such as a butterfly, in a freestanding state. The maximum conductivity and strength of the LCGO/AgNW composite were 17 800 S/cm and 4.2 MPa, respectively; these values are 24 and 4 times higher, respectively, than those of a previously developed self-healing electrode. The LCGO/AgNW composite self-healed internal damage in ambient conditions with moisture and consequently recovered 96.8% electrical conductivity and 95% mechanical toughness compared with the undamaged state. The electrical properties of the composite exhibited metallic tendencies. Therefore, these results suggest that the composite can be used as an artificial electronic skin that detects environmental conditions, such as compression and temperature. This self-healing artificial electronic skin could be applied to human condition monitoring and robotic sensing systems.

Freestanding bilayers of drop-cast single-walled carbon nanotubes and electropolymerized poly(3,4-ethylenedioxythiophene) for thermoelectric energy harvesting

Abstract Poly(3,4-ethylenedioxythiophene) (PEDOT) and single-walled carbon nanotubes (SWCNTs) are promising thermoelectric materials that exhibit flexibility and high performance. To realize improved structural and thermoelectric properties, we fabricated PEDOT/SWCNT bilayers consisting of drop-cast SWCNTs and electropolymerized PEDOT. We prepared two types of PEDOT layers using electrolyte solvents of water/methanol (Sample A) and acetonitrile (Sample B). Sample B achieved a flexible freestanding state, whereas Sample A was broken with part of the sample remaining on the substrate. Scanning electron microscopy revealed that the PEDOT layer in Sample A filled the gaps between the SWCNT bundles. The PEDOT layer in Sample B consisted of chain-like structures that mostly covered the surface of the SWCNT layer, which were speculated to increase the strength of the freestanding state. The structural properties of the bilayers were examined using Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Although slight structural differences were observed between Samples A and B, both samples exhibited the characteristics of PEDOT and SWCNTs. Measurement of the thermoelectric properties near 300 K afforded power factors of 12.5 and 13.9 μW/(m·K2) for Samples A and B, respectively. Therefore, we demonstrated the successful fabrication of freestanding PEDOT/SWCNT bilayers (Sample B) with relatively high thermoelectric performance.

Large-Gap Quantum Spin Hall States in the Bilayer Hexagonal Structure of Rhenium and Technetium Dinitrides: A First-Principles Study

Layered transition-metal dinitrides are the recently proposed cousins of transition-metal dichalcogenides, which exhibit extraordinary electronic and magnetic properties. In this work, through first-principles calculations, we have identified the lowest energy geometry of the ReN2 nanosheet, which is a bilayer hexagonal structure (BHS) akin to the MoN2 system. Such a BHS-ReN2 nanosheet possesses robust dynamical, thermal, and mechanical stabilities at the free-standing state. Interestingly, without spin–orbit coupling (soc), this BHS-ReN2 system exhibits a semimetallic feature with a d-character Dirac cone, for which a band gap is opened at the Dirac point when the soc effect is taken into account. As a result, the BHS-ReN2 nanosheet becomes a quantum spin Hall (QSH) insulator in the presence of soc, whose bulk gap reaches up to 384 meV, sufficiently large for the room-temperature QSH effect. The nontrivial topological feature is characterized by a Z2 = 1 invariant and a pair of topologically protected ed...

Polystyrene nanofibers for nonwoven porous building insulation materials

The building industry makes a great effort to reduce energy consumption. The use of nanotechnology is one of the approaches to surpassing the properties of conventional insulation materials. In this work, an industrial cost‐effective method to manufacture highly porous materials with excellent thermal insulation properties is described. The materials are prepared from polystyrene recovered from the building sector and electrospun as nanofiber‐based sheets. Varying electrospinning parameters allow controlling the morphology of the produced materials. The materials are obtained with differences in interfiber and inner‐fiber porosity and morphology. The thermal conductivity of the freestanding and compressed materials is evaluated. Those differences affect the insulation performance: the materials with higher interfiber porosity show better thermal insulation in the freestanding state. An increase of the inner‐fiber porosity leads to better insulation in the compressed samples. Insertion of carbon nanomaterials reduces the effects of the infrared Radiation. Nanofiber‐based insulation materials from the recycled expanded polystyrene (EPS) show thermal conductivity values of 20 to 25 mW/mK (ie, 20% to 30% below the thermal conductivity of the commercial EPS). The effect of integrating polystyrene nanofiber sheets into conventional wall‐building materials is also investigated in terms of thermal insulation. The nanofiber insulation sheets are sandwiched between two pieces of the building materials resulting in a drastic increase of the insulation effect. The materials have a great potential in using, for example, as thermal insulation for the restoration of historic buildings in the narrow central parts of the old towns.

Synergistic effects of thermal treatment and encapsulation of calcium phosphate nanoparticles on enhancing dimensional stability and osteogenic induction potential of free-standing PLGA electrospun membranes

Limited dimensional stability and osteogenic induction property of poly (lactide-co-glycolide) (PLGA) electrospun membranes hampered their applications in bone tissue engineering. Thermal treatment of fixed PLGA membranes at 50 °C for 2 h and further immersion in 75% ethanol at free-standing state were adopted in order to obtain a high stability and well-maintained fiber morphology. After the process, free-standing membranes were stable during incubation in PBS at 37 °C, the volumetric ratio was 59.0%, fibers became curved, and the average diameter was 816 nm. For as-electrospun PLGA membranes, the volumetric ratio was only 35.3%, showing that thermal treatment was effective to improve the dimensional stability. The addition of calcium phosphate nanoparticles in P5-T-F further increased the volumetric ratio (64.0%) and significantly improved the mechanical properties. The mineralization capacity of PLGA membranes was enhanced because of thermal treatment. Hemolysis ratios of all samples were ∼2% indicating good hemocompatibility of PLGA electrospun membranes. Proliferation of adipose derived stem cells from rats (rADSCs) on treated PLGA membranes was significantly faster than that on untreated one, especially for sample P-T-F. In addition to thermal treatment, the addition of calcium phosphate nanoparticles showed synergistic effects on improving mineralization property and osteogenic differentiation of rADSCs. When compared with P-T-F, P5-T-F had 153.0% higher ALP activity and 518% higher calcium mineral deposition based on alizarin red assay. Thermal treatment along with encapsulation of calcium phosphate nanoparticles in PLGA electrospun membranes demonstrated a great prospect for applications in bone tissue engineering.

Comparison of the mechanical strength of a monolayer of silver nanoparticles both in the freestanding state and on a soft substrate

A 7-nm-thick monolayer comprising myristate-capped silver nanoparticles (AgNPs) was fabricated by first drop casting an AgNP solution on the surface of a 10–100 μl water drop placed on a solid substrate. With the natural evaporation of the water, a monolayer slowly descended onto the substrate, the latter containing an array of 2.5-μm-diameter and 200-nm-deep holes, and finally formed circular freestanding monolayers in the holes. Nanoindentation measurement based on atomic force microscopy was carried out on the circular freestanding monolayer at its center, and the extending and retracting force–indentation curves were recorded to analyze further the mechanical properties of the monolayer. The force–indentation curves were evidently nonlinear, and so a two-term continuum-mechanics theory was used to interpret the results. By fitting the force–indentation curves using a two-term equation, the prestress and Young’s modulus of the freestanding AgNP monolayer were obtained as approximately 0.05 N/m and several gigapascals, respectively, which are consistent with the results reported in the literature. For comparison, we also studied the mechanical responses of AgNP monolayers and bilayers on a soft polydimethylsiloxane (PDMS) substrate by using nanoindentation. Because the AgNP monolayer was stiffer than the PDMS substrate, it was possible to measure the mechanical response of the former despite it being only 7 nm thick. The mechanical strength of the freestanding AgNP monolayers was considered to be dominated by the attractive interactions between the interdigitated hydrocarbon chains of the myristate.

Capability evaluation of self-location machining algorithm for ultra-precision workpiece based on SVD

In order to further improve the final precision, efficiency and cost-effectiveness of ultra-precision surface modification, and optimize the process direction and process decision-making of ultra-precision self-positioning processing, this paper studies the point cloud fusion process of self-positioning processing algorithm for ultra-precision workpieces. Based on the evaluation, it proposes a self-positioning processing algorithm capability evaluation method based on SVD. Firstly, based on the kinematics method, the matrix representation of point cloud fusion is established. The transformation matrix representation of self-positioning results is established for the translation, rotation and compound motion, respectively. Then the self-positioning point cloud fusion transformation matrix is obtained. A singular value decomposition is performed to obtain a singular value list of the transformation matrix. finally, the largest singular value in the list is used to characterize the self-positioning processing algorithm. By analyzing the free-precision states of a certain type of ultra-precision blade (a total of 1078 sets of free-standing state) it is found that the proposed evaluation index can correctly characterize self-positioning under the condition of independent translation and independent rotation. For the independent translation, the self-positioning processing algorithm can be positioned normally, and the maximum singular deviation value is also less than the pre-set value. For the independent rotation, when the angle is less than 45°, the self-positioning machining can be correctly performed. The singular value difference also approaches zero. Above 45°, the algorithm's self-positioning machining capability deteriorates, and this feature can be correctly captured by the proposed indicators. For the composite motion consisting of translation and rotation, the proposed index shows that about 35% of the cases can be correctly self-positioned, and the rest can not be correctly self-homing. It indicates that the indicators established by the proposed method can correctly characterize the self-positioning machining algorithm.