Nanometer-level Precision Research Articles

Single Atom Engineering for Nanorobotics.

The fields of single atom engineering represent cutting-edge areas in nanotechnology and materials science, pushing the boundaries of how small we can go in engineering functional devices and materials. Nanorobots, or nanobots, are robotic systems scaled down to the nanometer level and designed to perform tasks at similarly small scales. Single atom engineering, on the other hand, involves manipulating individual atoms to create precise materials and devices with controlled properties and functionalities. By integrating single atom engineering into nanorobotics, we unlock the potential to enable the precise incorporation of multiple functionalities onto these minuscule machines with nanometer-level precision. In this perspective, we describe the nascent field of single atom engineering in nanorobotics.

Preparation of Retinal Samples for Volume Electron Microscopy.

Volume electron microscopy (Volume EM) has emerged as a powerful tool for visualizing the 3D structure of cells and tissues with nanometer-level precision. Within the retina, various types of neurons establish synaptic connections in the inner and outer plexiform layers. While conventional EM techniques have yielded valuable insights into retinal subcellular organelles, their limitation lies in providing 2D image data, which can hinder accurate measurements. For instance, quantifying the size of three distinct synaptic vesicle pools, crucial for synaptic transmission, is challenging in 2D. Volume EM offers a solution by providing large-scale, high-resolution 3D data. It is worth noting that sample preparation is a critical step in Volume EM, significantly impacting image clarity and contrast. In this context, we outline a sample preparation protocol for the 3D reconstruction of photoreceptor axon terminals in the retina. This protocol includes three key steps: retina dissection and fixation, sample embedding processes, and selection of the area of interest.

Monocrystalline Nickel Nanogrinding Subsurface Deformation-Layer Depth Study Based on Orthogonal Tests

Nanogrinding is one of the main technologies for machining complex surface shapes with nanometer-level precision. The subsurface deformation depth, as an important index of machining quality, directly affects the service life and mechanical properties of machined parts. In order to explore the factors that influence subsurface deformation depth, this work investigated the effects of three factors, namely, grinding speed, grinding depth and crystal orientation, along different crystal planes at the depth of the subsurface deformation layer in a monocrystalline nickel nanofabrication process. By combining molecular dynamics simulation and orthogonal tests, the results showed that, among the three aforementioned factors, the influence of crystal orientation at the depth of the subsurface deformation layer was the greatest, followed by that of grinding depth, while the influence of grinding speed was the weakest. Through the orthogonal tests, the factors affecting the significance of subsurface deformation depth were analyzed, and the results were found to be more meaningful compared with those of current single-factor studies. Meanwhile, in-depth exploration of the nanogrinding mechanism can provide the necessary theoretical basis for the development of nanomachining technology, which is of great significance for the improvement of ultra-precision cutting technology.

Quality inspection of cube beam splitters by awhite light interferometric approach.

Beam splitters have a wide range of applications as a key component in optical systems. Adopting beam splitters with geometric defects in an optical system, e.g., an interferometric measurement system, may cause additional optical path difference and degrade the measurement accuracy. The quality inspection of beam splitters is essential to meet the accuracy requirements for modern optical systems. Most of the current quality inspection methods rely on inefficient and inaccurate manual observation. Therefore, for commonly used cube beam splitters (CBSs), we propose a digital method to quantify the geometric quality based on the white light interferometric principle. A Fourier domain analysis is used to calculate the CBS misalignment error and perpendicularity error. This method is verified by inspecting six different CBS samples. The experimental results show that all samples have varying degrees of misalignment and perpendicularity errors. The maximum perpendicularity error is 0.93°, and three of the six samples have misalignment errors larger than 50µm. Nanometer level precision of the misalignment measurement can be achieved.

Cyber-Physical Systems Framework for Predictive Metrology in Semiconductor Manufacturing Process

The process of semiconductor manufacturing is very complex, and the downtime caused by equipment degradation at any process stage reduces yield and production efficiency. Thus, semiconductor machines’ maintenance and calibration are important in maintaining stable production output and yield improvement. Traditionally, semiconductor manufacturers emphasize the importance of product quality to distinguish product defects. However, as semiconductor reaches nanometer-level precision, monitoring process quality is necessary to control process variability and achieve optimal yields. This paper presented a 5-level Cyber Physical Systems (CPS) predictive metrology architecture to investigate the process quality. The proposed architecture performs a peer-to-peer comparison to satisfy self-comparison ability, which is critical for chamber-to-chamber matching in the semiconductor manufacturing process. This concept has been demonstrated using the 2016 PHM public dataset in which the material removal rate was predicted in the chemical-mechanical planarization process. The results show that this innovative 5-level CPS predictive metrology framework is promising and feasible.

Radial Error Motion Measurement and Its Uncertainty Estimation of Ultra Precision Axes of Rotation with Nanometer Level Precision.

The radial error is the key performance indicator of ultra-precision axis. In order to measure and evaluate the radial error of ultra-precision axis with nanometer accuracy, a measurement system with an accuracy of nanometer based on capacitive displacement probes and standard spheres is developed. The nonlinearity error of capacitive displacement probes, misalignment error of the probes, eccentric error of standard spheres, error caused by environment temperature change, environment vibration and error separation methods are analyzed and the effects of the above factors are obtained; Multiple measurement examples carried out with the measurement system this paaper constructed indicate the repeatability of the measurement system reaches 10.5 nm and the roundness error of artifact separated is less than 4.03 nm. In order to evaluate the measurement dispersion of the ultra-precision axis radial error, the major uncertainty components and the complete process of the comprehensive evaluation of the measurement uncertainty are proposed. The combined uncertainty of radial error motion measurement of the ultra-precision axis with Donaldson reversal is 31.64 nm (k = 2).

Focus on software, data acquisition, and instrumentation

Focus on software, data acquisition, and instrumentation

Fuzzy sliding mode control of piezo-driven stage.

The motion stage with flexible hinges as a guiding mechanism can realize nanometer-level precision positioning. This stage uses a piezoelectric (PZT) actuator as the driving unit. In order to describe the mechanical characteristics of this piezo-driven stage, a double-parallel four-bar mechanism based on eight flexible hinges is analyzed. The natural frequency and modal of this stage are analyzed with the finite element method. In order to reduce the hysteresis influence of the PZT actuator, the model parameters based on the Bouc-Wen hysteresis model are identified by using the particle swarm optimization algorithm, and the boundedness of the hysteresis phenomenon is determined by this model. On this basis, the PZT hysteresis is regarded as a disturbance, and a proportional-integral-differential (PID)-type fuzzy sliding mode control (FSMC) is designed. Taking errors and the derivation in the errors as input and the parameters of the PID sliding surface as the output, the fuzzy sliding mode function is constructed. In addition, taking the absolute value of the sliding mode function as the input and the adjustment factor of the switching control as the output, the fuzzy switching control is constructed. Finally, the effectiveness of the FSMC is verified through several experiments.

First result of orbit verification of Taiji-1 hall micro thruster

The Hall Micro Thrusters (HMTs) use cold gas or accelerated plasma dual mode to provide ultra-precise spacecraft altitude control. They were operated in space for the first time as part of the demonstration payloads on Chinese Academy of Science’s (CASs) Taiji-1 spacecraft since September 2019. Hall Micro Thruster Assemblies (HMTAs) were the actuators in drag-free control, and will compensate the nonconservative force for gravity wave observatories. The HMTAs meet the requirements of operating at 5–100 [Formula: see text] N of thrust with 0.7 [Formula: see text] N resolution and [Formula: see text]0.6 [Formula: see text] N/Hz[Formula: see text] (0.01–1 Hz) noise to deliver the nanometer-level precision control as fast as 30 ms measured by Gravitational Reference Sensor (GRS). A transfer function model in z-domain was fit and used to filter HMTs cathode voltage to predict GRSs thrust noise response. Simulations of a single or dual-frequency disturbance and the corresponding compensation demonstrated that HMTAs could deliver the required thrust profile expected. The capability to meet the requirements of thruster noise in drag-free control is critical for future missions because the acceleration noise on test mass directly relates to the gravity wave signa l. Preliminary in-orbit verification of Taiji-1 has showed HMTAs’ great potential in future, and the data in the experiments are presented in this paper.

Programmable Cocrystallization of DNA Origami Shapes.

Assembly of distinct types of species, particularly possessing anisotropic configurations, is the premise to broaden structural diversity and explore materials' collective properties. However, it remains a great challenge to programmably cocrystallize manifold anisotropic nanoparticles with the desired assembly mode, because it requires not only the complementarity of both sizes and shapes but also the control over their directional interactions. Here, by introducing DNA origami technique into lattice engineering, we synthesize two types of DNA nano-objects with different symmetries and program the heterogeneous functional patches precisely on their surfaces with nanometer-level precision, which could guide further assembly of these nano-objects. We show that these anisotropic DNA nano-objects could be cocrystallized along specified modes via modulating the combination of surface patches. The highly ordered DNA crystals were thoroughly evidenced by techniques including small-angle X-ray scattering and electron microscopy after careful encapsulation of a thin layer of silica on these DNA nano-objects. Our strategy endows distinct shapes of organic DNA origami structures with regulation features to control the sophisticated modes of cocrystallization of these diverse components, laying a foundation for designing and fabricating customized three-dimensional structures with given optical and mechanical properties.

Tracking Down the Fast and Superprocessive KIF1A with Gold Scattering Microscopy

The kinesin-3 family member KIF1A is a neuronal kinesin that performs long-distance anterograde vesicle transport in axons and dendrites. Single molecule studies observe KIF1A velocities > 1 μm/s and average run lengths > 5 μm, making KIF1A one of the fastest and most processive members of the kinesin superfamily; however, the mechanistic basis of these high speeds and long run lengths is unknown. One prevailing model for superprocessivity holds that the positively-charged “K-loop” in the KIF1A motor domain diffusively tethers the motor to the negatively-charged microtubule, which prevents complete dissociation of the motor and effectively links together short runs. However, this model does not account for how KIF1A reaches such high speeds, or what role the K-loop plays in the ATP-driven stepping mechanism. To address these questions, we labeled the C-terminus of a truncated KIF1A dimer with a 30-nm gold nanoparticle and used interferometric scattering microscopy (iSCAT) to observe the KIF1A stepping cycle at sub-millisecond time scales and nanometer-level precision. Our preliminary data reveal that KIF1A motility is characterized by periods of directed stepping interspersed by periods where the motor is statically bound to the microtubule, rather than diffusively tethered, as predicted by the K-loop model. An alternate explanation for superprocessivity, that could also account for the stepping speed, is that during each step the K-loop ensures the tethered head binds to the microtubule hundreds of times faster than the bound head detaches from the microtubule. Our ongoing investigations employ a KIF1A construct with a nanoparticle-functionalized motor domain to characterize the nature of these paused states, and the duration of the one-head bound state in the chemomechanical cycle.

DNA Origami-Mediated Substrate Nanopatterning of Inorganic Structures for Sensing Applications.

Structural DNA nanotechnology provides a viable route for building from the bottom-up using DNA as construction material. The most common DNA nanofabrication technique is called DNA origami, and it allows high-throughput synthesis of accurate and highly versatile structures with nanometer-level precision. Here, it is shown how the spatial information of DNA origami can be transferred to metallic nanostructures by combining the bottom-up DNA origami with the conventionally used top-down lithography approaches. This allows fabrication of billions of tiny nanostructures in one step onto selected substrates. The method is demonstrated using bowtie DNA origami to create metallic bowtie-shaped antenna structures on silicon nitride or sapphire substrates. The method relies on the selective growth of a silicon oxide layer on top of the origami deposition substrate, thus resulting in a patterning mask for following lithographic steps. These nanostructure-equipped surfaces can be further used as molecular sensors (e.g., surface-enhanced Raman spectroscopy (SERS)) and in various other optical applications at the visible wavelength range owing to the small feature sizes (sub-10 nm). The technique can be extended to other materials through methodological modifications; therefore, the resulting optically active surfaces may find use in development of metamaterials and metasurfaces.

Simplified phase-stable dual-comb interferometer for short dynamic range distance measurement.

A simplified phase-stable dual-comb interferometer for absolute distance measurement within a short dynamic range is proposed in this paper. The experimental results demonstrate that stable phase-difference information and lower timing jitter can be obtained within a time delay of 2000 ns between the reference interference signal and measurement interference signal. Using the proposed technique, the time-of-flight (TOF) result can link directly to the carrier-wave interferometric (CWI) result in an average time of 20 ms and can reach 2 nm precision in 0.5 s averaging time. Millimeter-scale measurement dynamic range and nanometer-level precision can thus be achieved without additional noise suppression. This method can also be applied at different stand-off distances.

High-performance optical coherence velocimeter: theory and applications.

We proposed a high-performance optical coherence velocimeter (OCV) based on broadband optical interference which achieves spatial resolution from interference cancellation or enhancement of different components of the broadband light. There is a challengeable issue for OCV that the interference fringes become blurred when the velocity of detected object is relatively large, hindering the pace of OCV application in high-velocity field. To resolve this, the relationship between blurry coefficient and OCV system parameters (e.g., exposure time, central wavelength, bandwidth of source) was derived. It was found that blurry coefficient changed with oscillatory decay form and reached the minimum at each order blurry velocity. It showed that maximum measurable velocity of OCV systems could reach 10th order blurry velocity. The measurement of vibration of the loudspeaker driven by a function signal generator was employed to experimentally verify the velocity measurement performance of the system. The experiment demonstrated that the developed OCV can provide large velocity measurement ranges from static to 25.2 mm/s with nanometer-level precision and maximum measurable vibration frequency of up to 50 kHz. However, in theory, the theoretical maximum measurable velocity can be up to 1.06 m/s for current OCV configuration. The OCV has high precision, large dynamic range, and high-velocity measurement capability, making it attractive for applications in mechanical structure vibration monitoring and acoustic measurement.

Nondestructive determination of the core size of a hollow-core photonic bandgap fiber using Fabry-Perot interference.

In this Letter, we propose a simple and nondestructive method for the determination of the core size of a hollow-core photonic bandgap fiber (HC-PBF) and its axial uniformity based on a Fabry-Perot cavity induced by a pair of opposite silica-air interfaces within the hollow core. The experimental results indicate that the core size test of the HC-PBF has a nanometer-level precision, and its axial uniformity test has an ultimate spatial resolution of tens of microns. The method provides an effective and precise tool for the investigation of the hollow-core size and its longitudinal evolution.

Controllable growth of ZIF-8 layers with nanometer-level precision on SiO2 nano-powders via liquid phase epitaxy stepwise growth approach

Engineering the growth of MOFs on substrates at the nanometer or even the molecular level is of major interest for taking MOFs beyond their uses as bulk materials and creating multifunctional features with advanced applications. Herein we report the SiO2@ZIF-8 (core@shell) monodisperse nanospheres synthesized through a liquid-phase epitaxy stepwise growth (LPE) strategy. The controlled growth of ZIF-8 shell with nanometer-level precision could be achieved. The growth of the ZIF-8 shell can be adjusted by manipulating the influencing factors, such as growth circles, precursor solvent, precursor concentration, core size, synthesis temperature and implementation methods. The formation processes of ZIF-8 shell on the SiO2 surface using different precursor solvents were also deduced. The composite exhibited faster adsorption for bisphenol A with ultra-high adsorption capacity per unit ares compared to ZIF-8-only material. Such controlled growth of homogeneous ZIF-8 shell with nanometer-level precision is of paramount importance for the success of fabricating ZIFs layers in the channels ofmesoporous materialics. Further, this paves the way for integrated MOF materials to address a wide range of challenges in the areas of catalysis, rapid detection, adsorption and separation.

In-line metrology of nanoscale features in semiconductor manufacturing systems

Quality control and defect monitoring are of great importance to the semiconductor industry. This article presents a system to enable inspection of nanoscale features in-line with nanomanufacturing processes. The ultimate goal of this research is to integrate this metrology system into current semiconductor manufacturing processes to enable true in-line wafer inspection and quality control. In the system presented in this paper, AFMs that have been shrunk down on to a single MEMS chip are used to scan the surface of a sample. A flexure-based mechanism allows the MEMS-based AFM to be positioned over a millimeter range of motion, with nanometer level precision when properly actuated. The performance of the system in areas such as positioning repeatability, AFM stability and measurement resolution are evaluated in this study. Owing to the small size of single-chip AFM (1 million times smaller than a conventional AFM instrument), it is a good candidate for multipoint detection. Overall, the system presented in this paper significantly shortens inspection time and dramatically decreases the setup time required for an AFM to load, approach, and measure a sample making in-line inspection of nanoscale features in semiconductor manufacturing systems feasible.

DNA-Based Enzyme Reactors and Systems.

During recent years, the possibility to create custom biocompatible nanoshapes using DNA as a building material has rapidly emerged. Further, these rationally designed DNA structures could be exploited in positioning pivotal molecules, such as enzymes, with nanometer-level precision. This feature could be used in the fabrication of artificial biochemical machinery that is able to mimic the complex reactions found in living cells. Currently, DNA-enzyme hybrids can be used to control (multi-enzyme) cascade reactions and to regulate the enzyme functions and the reaction pathways. Moreover, sophisticated DNA structures can be utilized in encapsulating active enzymes and delivering the molecular cargo into cells. In this review, we focus on the latest enzyme systems based on novel DNA nanostructures: enzyme reactors, regulatory devices and carriers that can find uses in various biotechnological and nanomedical applications.

Precision design and control of a flexure-based roll-to-roll printing system

This paper presents the design, characterization, and control of a flexure-based roll-to-roll (R2R) printing system that achieves nanometer level precision and repeatability. The R2R system includes an unwinding/rewinding module, a web guide mechanism, and a core positioning stage consisting of two monolithic compliant X–Y stages that control the position/force of the print roller. During the printing process, capacitance probes, eddy current sensors and load cells are used to monitor the displacements of the flexure stage and contact force in real time. Control strategies, including decoupling, PID, and cascade control, have been implemented to decouple the cross-axis and cross-stage motion coupling effect and improve the overall precision and dynamic performance. In actual printing processes, the contact force and roller position can be uniformly controlled within ±0.05N and ±200nm respectively across a 4in. wide PET web. To demonstrate the performance, a positive microcontact printing (MCP) process is adapted to the R2R system, printing various fine metal patterns, e.g., optical gratings and electrodes, in a continuous fashion.

Focus on microscopy and photonics

Focus on microscopy and photonics