Micro-nano Manufacturing Research Articles

Fabrication and Electrochemical Characterizations of Strip Ultramicroelectrode Array Prepared by Nanoskiving

Abstract Strip ultramicroelectrodes (SUE) have been widely used in micro-nano manufacturing, trace element detection, and energy storage. Preparation of SUE is thus the basis for these applications. A method for the preparation of SUE and its array (SUEA) is proposed based on a nanoskiving technique. The effects of embedding materials and storage methods on electrode stability were investigated. The continuous and stable working time of 120 minutes and the storage time of 92 h were achieved. Furthermore, the effect of nanowire feature dimensions on the electrochemical properties of the SUE was analyzed. Parameters such as steady-state limiting current and reversible electron transfer were evaluated. Compared to SUE, the SUEA exhibits a ten-fold increase in steady-state limiting current. The findings in this study provide an approach to obtain high-performance SUE, which will promote the practical application of SUE in micro/nano electrochemical detection.

Coating-assisted picosecond laser ablation for microstructure fabrication of SiC ceramics.

Silicon carbide (SiC) ceramics have emerged as critical materials in the production of high-precision components. Ultrafast laser processing is deemed the optimal technique for micro-nano manufacturing of SiC. However, the permanent deposition layer induced by laser ablation can critically impact the precision of the component. In this work, a coating-assisted picosecond laser ablation (CAPLA) method was proposed, in which sacrificial photoresist coating was utilized to improve surface quality without efficiency loss. The coating serves to prevent the uncooled plasma from contacting with the substrate, thereby preventing the formation of a permanent deposition layer. By comparing the CAPLA method with laser direct ablation, the influence of laser parameters and photoresist coating characteristics on the deposition layer was investigated systematically. A processed surface devoid of deposition layers can be achieved by CAPLA with low pulse energy and a high number of scans. The uniformity is critical to ensure the transmission of the laser beam, and a larger thickness can improve the processing efficiency by increasing the limit of pulse energy capacity. Pin arrays and vacuum grooves for SiC ceramic vacuum chucks were fabricated to demonstrate the superiority of the CAPLA method. These results suggest that this method can be a novel and promising approach for high-precision component manufacturing.

Split ring hole metamaterial-enhanced pyroelectric detector for efficient multi-narrowband terahertz detection

Derived from infrared pyroelectric detection, typical terahertz (THz) pyroelectric detectors have low sensitivity at low-frequency THz bands. Based on the high-efficiency absorption of the metamaterial perfect absorber (MPA), a novel split ring hole metamaterial-enhanced pyroelectric detector is proposed to achieve efficient multi-narrowband THz detection. Using high frequency simulation software (HFSS), the dimensional parameters including ring radius, ring width, connection beam width, array period, and thickness, are optimized to enhance efficient multi-narrowband absorption. The as-optimized metamaterial-enhanced detectors are fabricated via micro-nano manufacturing technology. The voltage responsiveness and noise equivalent power of the metamaterial-enhanced detector are tested by THz focused optical path and compared with those of the typical pyroelectric detector and the simulated MPA absorptivity. The results indicate that the metamaterial-enhanced detector has a multi-narrowband detection capability at 0.245 THz, 0.295 THz, and 0.38 THz, which is close to the simulated MPA absorptivity. Compared to the typical pyroelectric detector, the split ring hole metamaterial-enhanced detector can simultaneously achieve thermal absorption, thermal conduction, and pyroelectricity in the same MPA structure, providing faster response speed above 100 Hz chopper frequency and two times higher detection sensitivity at multi-narrowband THz frequencies. This research can be used for THz sensing, absorption filtering, biological macromolecule detection, and other applications.

Recent Advances in Microrobots Powered by Multi-Physics Field for Biomedical and Environmental Applications.

Microrobots powered by multi-physics fields are becoming a hotspot for micro-nano manufacturing. Due to the small size of microrobots, they can easily enter small spaces that are difficult for ordinary robots to reach and perform a variety of special tasks. This gives microrobots a broad application prospect in many fields. This paper describes the materials, structures, and driving principles of microrobots in detail and analyzes the advantages and limitations of their driving methods in depth. In addition, the paper discusses the detailed categorization of the action forms of microrobots and explores their diversified motion modes and their applicable scenarios. Finally, the article highlights the wide range of applications of microrobots in the fields of biomedicine and environmental protection, emphasizing their great potential for solving real-world problems and advancing scientific progress.

The flexible and distributed pressure sensor with 64 units for on-line gait recognition analysis

With the rapid development of flexible electronic technology, human gait recognition device is also developing in the direction of flexibility, refinement, and intelligence. In this paper, a gait recognition system with the advantages of being non-invasive and flexible is proposed and prepared to collect complex pressure information of human plantar and identify different gaits accurately. A flexible and distributed pressure sensor with a structure of eight rows and eight columns is designed and fabricated by the screen printing process and micro-nano manufacturing technology. The insole shape can be placed directly into a sneaker for easy wearing, while 64 pressure sensing units allow for more accurate detection of complex plantar pressure information. In addition, based on the “voltage mirror” principle and the feature threshold analysis method, a distributed pressure acquisition circuit and an online gait recognition software are developed respectively to realize time-sharing decoupling of complex output signals from multiple pressure sensing units and online real-time display of different gaits. Finally, Different human gait recognition experiments have also been carried out. The results show that the test error of the pressure sensing unit is better than 8.28%. The gait recognition system can realize the reliable and accurate online real-time identification of slow walking, fast walking, and different leaning directions, which shows great potential and value in the fields of medical diagnosis, health monitoring, gait correction and artificial intelligence.

Fabrication of an X-shaped micro-copper structure containing a merging joint based on localized electrochemical deposition

Local electrochemical deposition (LECD) has proved to be an efficient and economical method for fabricating three-dimensional micron structures. Realizing complex structures that join up when deposited using LECD has been complex; therefore, the fabrication of an X-shaped joining structure was investigated in this study. A horizontal trace model was proposed, and the effects of the number of deposition layers and the horizontal sweep width on the merging joint were studied. The horizontal trace model could complete the merging joint. Multiple deposition layers and a large horizontal sweep width could stabilize and better connect the X-shaped structure containing merging joints. The merging mechanism of the X-shaped structure was also investigated using COMSOL. The stable deposition of the joining structure enables the LECD method to have a broader range of applications in micro-nano manufacturing.

Recent Advances and Prospects of Optical Metasurfaces

As an artificial planar composite medium, optical metasurfaces exhibit powerful multidimensional optical modulations at the subwavelength scale. With the aid of intelligent algorithms, versatile wavefront engineering and holographic multiplexing based on optical metasurfaces are being intensively developed. Micronano manufacturing technology provides indispensable support for proof-of-concept and mass production. With the support of these advanced technologies, optical metasurfaces have been developed for a wide range of applications and their compactness, versatility, and compatibility have been fully demonstrated. In this Perspective, we summarize recent advances. In addition, we discuss the challenges and prospects of optical metasurfaces.

Research advances in simple and compact optical imaging techniques

Computational imaging enables optical imaging systems to acquire more information with miniaturized setups. Computational imaging can avoid the object-image conjugate limitation of the imaging system, and introduce encoding and decoding processes based on physical optics to achieve more efficient information transmission. It can simultaneously increase the amount of information and reduce the complexity of the system, thereby paving the way for miniaturizing imaging systems. Based on computational imaging, the simple and compact optical imaging techniques are developed, which is also called simple optics. To develop miniaturized optical imaging elements and integrated systems, simple optics utilizes the joint design of optical system and image processing algorithms, thereby realizing high-quality imaging that is comparable to complex optical systems. The imaging systems are of small-size, low-weight, and low-power consumption. With the development of micro-nano manufacturing, the optical elements have evolved from a single lens or a few lenses, to flat/planar optical elements, such as diffractive optical elements and metasurface optical elements. As a result, various lensless and metalens imaging systems have emerged. Owing to the introduction of encoding process and decoding process, an optical imaging model is developed to represent the relationship between the target object and the acquired signal, from which the computational reconstruction is used to restore the image. In the image restoration part, the algorithms are discussed in three categories, i.e. the classic algorithm, the model-based optimization iterative algorithm, and the deep learning (neural network) algorithm. Besides, the end-to-end optimization is highlighted because it introduces a new frame to minimize the complexity of optical system. In this review, the imaging techniques realized by simple optics are also discussed, such as depth imaging, high-resolution and super-resolution imaging, large field of view imaging, and extended depth of field imaging, as well as their important roles in developing consumer electronics, unmanned driving, machine vision, security monitoring, biomedical devices and metaverse. Last but not least, the challenges and future developments are prospected.

Overview of Advanced Micro-Nano Manufacturing Technologies for Triboelectric Nanogenerators

In the era of the Internet of Things, various electronics play an important role in information interaction, in which the power supply is an urgent problem to be solved. Triboelectric nanogenerator (TENG) is an emerging mechanical energy harvesting technology that can serve as a power source for electronics, which is developing towards high performance, miniaturization and integration. Herein, the advanced micro-nano manufacturing technologies are systematically reviewed for TENGs. First, film preparation such as physical vapor deposition, chemical vapor deposition, electrochemical deposition, electrospinning and screen printing for triboelectric layers are introduced and discussed. Then, surface processing, such as soft lithography, laser ablation, inductively coupled plasma and nanoimprint for micro-nano structures on the surface of triboelectric layers are also introduced and discussed. In addition, micro-electromechanical system fabrication for TENG devices such as acoustic and vibration sensors, is introduced, and their current challenges are analyzed. Finally, the challenges of the advanced micro-nano manufacturing technologies for the TENGs are systematically summarized, and further development is prospected.

Development of a cross-scale 6-DOF piezoelectric stage and its application in assisted puncture

Micro-nano manipulation technology has been widely applied in ultra-precision fields such as micro-nano manufacturing and biomedical engineering. Multi-DOF ultra-precision stage is one of its key components. This study proposes a 6-DOF piezoelectric stage (6-DOF-PS) to solve the problem that few existing 6-DOF stages can take the characteristics of large range, high resolution and low coupling into account together. The optimal mechanism design scheme of the proposed stage was chosen by comprehensively considering three critical factors of the workspace, the parameter sensitivity of connecting rods and inertia load moment. The structure design and working principle of the 6-DOF-PS were introduced. A prototype of the 6-DOF-PS was fabricated and a series of experiments were performed. The experiment results showed that it achieved 6-DOF motion with the large range of 5 mm × 5 mm × 5 mm × 68° × 68° × 360° and the high resolution of 22.6 nm × 18.9 nm × 12.4 nm × 0.12 µrad × 0.13 µrad × 0.40 µrad, and the maximum coupling error was 5.03% in the 6-DOF motion. Therefore, 6-DOF motion with large range, high resolution and low coupling was achieved through this stage. Furthermore, it also had a good load carrying capacity. Finally, its application experiments in assisted puncture were carried out, the position and posture of the vascular models were adjusted by the 6-DOF motion, and the puncture operation was completed successfully with the assistance of the proposed 6-DOF-PS.

Biomedical materials to repair damaged tissues and organs in sports dance performances

Micro-nano manufacturing of inorganic—organic composite tissue and organ engineering scaffolds is a field of biomaterial research that has emerged in recent years. Cell scaffolds for repairing damaged tissues and organs composed of degradable materials are one of its core technologies. Based on this research background, the article analyzes the efficacy of bone scaffold biomedical materials implanted in the injured leg caused by dance exercise. And through finite element analysis and elastic modulus analysis of the bracket’s stress and strain curves. The study found that the stiffness of the bone scaffold biomedical material is reduced after entering the human body. Biomedical materials can exert their toughness characteristics under the action of human bone proteins.

Micro-nano manufacturing of Ti6Al4V antibacterial surface

Ti6Al4V is often used in the manufacture of biomedical equipment due to its excellent properties such as light weight, high strength and good corrosion resistance in the physiological environment. Therefore, it is very important to form a non-toxic antibacterial surface on Ti6Al4V material. In this paper, a micro-nano manufacturing method of Ti6Al4V antibacterial surface was studied. In this process, the surface was firstly cut by low speed wire electrical discharge machine, and then the cut surface was hydrothermal treated. The antibacterial surface prepared by this process had the characteristics of non-toxic, stable structure, and would not cause bacteria to develop drug resistance. The preparation process is simple, friendly to the environment, and can realize mass production. The influence of different cutting times on the antibacterial surface morphology in the low speed wire electrical discharge machining was studied. The micron-grade surface obtained after three cutting times was of good quality, less molten material and high wear resistance. The influence of two etching agents mixed with different molar ratios on the micro-nano structure of antibacterial surface during hydrothermal treatment was analyzed. When the molar ratio of A and B solution was 14:1, the surface structure of the best size was obtained, and the wear resistance of the micro-nano structure surface was improved compared with the polished surface. The antimicrobial test results show that the surface of the prepared workpiece had obvious antimicrobial properties compared with the surface of the polished part after cultured for 24 h. The bacteriostatic rate of Escherichia coli was 49.55%. Based on the above, the research results of this paper have positive significance for the development of micro-nano antibacterial surface.

Using sugar as a mask material (SAAMM) in micro-nano fabrication: a high-performance, green and simple method

Sugar is a natural food and a common organic compound that widely exists in nature. Sugar features easy patterning, solubility in water, environmental friendliness, low cost, and easy combination with micro-nano process. In this study, sugar is proposed to be used as a micro-nano mask material in micro-nano fabrication. Results show that sugar can be easily used to fabricate various kinds of micro-nano mask patterns on different wettability substrates. The fabrication method based on sugar mask has many advantages; it is diverse, simple, pollution-free, and inexpensive. Besides, sugar is strongly compatible with micro-nano fabrication technology, because it can maintain good peeling properties, good viscosity, and good stability in subsequent micro-nano fabrication and achieve the high-quality transfer of mask patterns. In addition, graphite super-lubricity micro-nano movable devices are made through the proposed sugar mask method, which also has good and reliable performance compared with e-beam lithography. Compared with micro-nano fabrication based on photoresist masks, micro-nano fabrication based on the sugar mask is simpler and cheaper. In the micro-nano processing of the sugar mask, the lift-off and removal of residual sugar can be easily completed using water. In summary, we believe that sugar as a mask material is effective and can be widely used in micro-nano manufacturing.

Compression spin bio-inspired arm: A conceptual model based on compression–torsion cubic mechanical metamaterials with variable cross-section

Robots are designed to achieve muscle contraction, body curling, stress response, and other complex movements. Inspired by the arm configuration and compression–torsion cubic mechanical metamaterials (CTCMM), the CTCMM with variable cross-section (V-CTCMM) and the offset CTCMM with variable cross-section (OV-CTCMM) by bionic designing are proposed. The novel microstructure can meet the shape requirement of the whole structure section. Through theoretical derivation for simplified cylinder models, the variation laws of torsion angle under torque in the V-CTCMM and OV-CTCMM are obtained. Three specific unit cells are studied under compression by numerical simulation and experiments. Compared with double rods CTCMM, the multi-rods CTCMM with variable cross-section (MRV-CTCMM) shows bigger torsion angle and larger stiffness. According to the characteristics of unit cells, the whole structure is constructed in the radial and axial direction with multiple expansion modes. Considering the stiffness of the structure in radial direction, straight rods and chiral rods construction methods are proposed to improve in-plane stiffness. The result shows the dumbbell structure can reach the best torsion angle among gradient structures in axial direction. With the progress of micro-nano manufacturing technology, 3D V-CTCMM shows a broad industrial application prospect in the fields of deformable structure, shape-memory controller, intelligent flexible microelectronics, and so on.

Effect of dielectric barrier discharge on ceramic surface properties

Ceramics, as a commonly used insulating and thermally conductive material, has a wide range of applications in the field of micro-nano manufacturing. In recent years, research on ceramic bonding has also increased. However, ceramic bonding has some problems such as bonding failure and low bonding quality. Learning from other commonly used bonding materials, the important factor for the success of bonding is the surface properties of the material. Therefore, in this study, the surface of ceramic was treated by dielectric barrier discharge (DBD) to improve surface properties. The effects of dielectric barrier discharge on the surface properties of ceramic is investigated from the three aspects: hydrophilic angle, surface energy and surface morphology. In the dielectric barrier discharge experiment, blind via glass is used as the blocking medium for the upper electrode. The lower electrode is covered by ceramic, and the ceramic is also the material to be treated. The influence of processing time, discharge voltage and discharge frequency on the treatment effect is investigated in the experiment. The hydrophilic angle and surface energy of the treated ceramics are measured and calculated by contact angle measuring instrument, and the surface morphology was observed by scanning electron microscopy. The results show that the longer the discharge treatment time is, the larger the discharge output voltage is, the smaller the discharge gap is, the faster the hydrophilicity of the surface of the ceramic sheet is, and the higher the activation energy is. The damage of the ceramic surface after treatment is small, and the impurities on the surface are destroyed. In general, the surface properties of ceramics after dielectric barrier discharge treatment are better than before.

Progress of photonic topological insulators in circuit-QED lattice and optomechanical array

Topological insulators are a new kind of quantum state of the matters. Similar to the traditional insulators, topological insulators also possess the bulk gap and the insulating bulk states. The difference is that topological insulators have the conducting edge states on their surface or boundary at the same time. These conducting edge states are immune to the local disorders and perturbations since they are protected by the nonlocal topological invariant. The different values of the topological invariant usually correspond to different topological phases. The topological protection of the topological invariant originates from the topological structure of the energy bands in momentum space, which leads that the topological insulator has many potential applications in quantum information processing and quantum computing. The robust quantum state transfer can be realized with a high fidelity via the edge channel of the topological insulator, in which the process of state transfer is robust to the local disorders and perturbations since the edge channel is protected by the energy gap. Also, the topological quantum computing can be implemented by dint of the non-Abelian anyons and Majorana zero modes. These potential applications make the topological insulator have many significant research values in quantum information processing and quantum computing. However, the experimental realization of the topological insulators based on the traditional electronic system has many challenges both in experimental techniques and experimental detections. From the perspectives of energy spectrum and Bloch theorem, electron, photon, and phonon present certain similarity. So, in the field of bosons with integral spin, the quantized topological states of light, sound, mechanical motion should also be implemented similarly, which provides opportunity to conveniently realize the topological insulators in experiment based on different bosonic optical systems. With the fast-developing fields of micro-nano manufacturing and materials processing technology in recent years, all kinds of quantum optical platforms become reliable candidates for the simulations and mappings of the topological insulators, which are the so called photonic topological insulators. Based on the bosonic statistical properties in these platforms, the relevant topological issues can be easily realized and even detected directly. For example, the circuit-QED lattice, consisting of a series of superconducting resonators and qubits, is becoming a more and more appealing and reliable candidate for the mappings and the simulations of all kinds of topological insulators due to its advantages of tunability and scalability. Many topological issues based on the one dimensional circuit-QED system have been investigated, such as the mapping of the high-dimensional topological Chern insulator, the topological edge state and the topological invariant, the detection of topological edge states, etc. Another promoting quantum optical platform is the optomechanical array, which is composed by single optomechanical system. The optomechanical array contains the photons and the phonons at the same time, which has many potential advantages in the mapping and the detection of all kinds of topological issues. However, the topological phenomenon based on the optomechanical array is still rarely investigated. Thus, we summarize the development in the field of the topological insulators and review the latest research progress of photonic topological insulators in circuit-QED lattice and optomechanical array.

Terahertz coding metasurface based vanadium dioxide

Terahertz (THz) has the characteristics of non ionization, penetration, water absorption, high resolution, etc. It has shown an important application prospect in many fields, such as non-destructive testing, imaging and communication. However, THz is in the transition frequency band ranges from macro-electronics to micro-photonics, so, it belongs to the interdisciplinary field, forming the “terahertz gap” in electromagnetic wave. In recent years, with the continuous development and improvement of THz radiation source and detection technology, the THz modulation technology has gradually aroused the interest of researchers. Metamaterials with many properties that natural materials do not possess provide a common way to control THz. The two-dimensional structure of a metamaterial is called a metasurface. The coding metasurface encodes the phase digitally so that the electromagnetic wave can be regulated. It is proposed that it is first in the microwave band and then extended to the THz band. In the microwave band, the number, direction and amplitude of the far-field beams can be changed dynamically by programming, which is connected with the integrated circuit such as FPGA by using diodes, but due to the limitation of diode size and micro-nano manufacturing technology, the programmable metasurface in microwave band cannot be well used in THz band. In order to improve the flexibility of THz coding metasurface, in this paper we choose the phase change material vanadium dioxide (VO<sub>2</sub>) to active modulation coding metasurface. In this paper, we analyze the VO<sub>2</sub>’s insulating state before the phase transformation and metallic state after the phase transformation. Then designing an active control 1 bit coding metasurface by using the influence of the two states on the amplitude and phase of the unit structure, which is composed of VO<sub>2</sub>, polyimide and aluminum, can not only realize the basic function of coding metasurface adjusting the electromagnetic wave beams, but alsoimplement the switching of two kinds of far-field beams at 1.1 THz for the same coding sequence by thermal stimulated VO<sub>2</sub>. The coding metasurface also realizes the switching between two near-field focal points at 1.1 THz for the same coding sequence. Based on the effect of VO<sub>2</sub> on the phase, this coding metasurface provides a new way to adjust and control the THz wave flexibly, and will have a great application prospect in THz transmission, imaging and communication.

Determination of power hardening elastoplastic constitutive relation of metals through indentation tests with plural indenters

The accurate acquisition of the elastoplastic mechanical parameters of metals through in situ indentation tests is an important topic, especially for the technological domains of micro-nano manufacturing. In view of existing uniqueness and effectiveness problems of the current indentation reverse analyses, a method for extracting the power hardening elastoplastic constitutive relation using plural indenters is proposed. Elastic modulus E and Poisson's ratio υ are obtained on the basis of the test result in cylindrical flat punch indenter, and the loading curves are corrected by eliminating the indentation size effects of two pyramid indenters with different equivalent semi-cone angles. The yielding stress σy and strain hardening exponent n can be uniquely determined by combining the representative stress σr under two pyramid indenters that are obtained from the numerical inversion analyses with corresponding representative plastic strain ɛr of certain pyramid indenters. Specific implementing procedures are carried out on Cu and Al. Results show the effectiveness and accuracy of this analytical method.

Bibliometric analysis of micro-nano manufacturing technologies

Manufacturing is the primary industry promoting economic and social development. For the past 30 years, the global trends of preciseness and device miniaturisation have promoted manufacturing to the micro (μ) and nano (η) scale. Identification of the most promising micro-nano manufacturing technologies (MNMT) is of interest to industry, academia and private and national science investing foundations. Considering the exponential broadening of the research area and an enormous volume of literature, providing an overview of the state of the art is far beyond the scope of a technical review paper. This study performs bibliometric analysis of a stream of academic literature devoted to μ- and η-machining. The main goals of the analysis are to assess the current core and trends in the field of MNMT. Literature and citation statistics from 1988 were collected from the Web of Science, Google Scholar, Scopus, Engineering Village, ScienceDirect and SpringerLink databases and were then analysed and illustrated with Microsoft Excel and VOSviewer software. The top keywords, articles, journals, authors, universities and countries were identified according to different parameters. The index of normalised influence was offered to evaluate the top element in each category. We observed that the most powerful keywords were present in well-known articles published in prominent journals by authoritative scientists at leading universities in the countries that are most actively engaged in MNMT. The implications of the research outcomes for investors and academicians are summarised in the conclusion.

Laser nanojoining of copper nanowires

Single nanowire becomes attractive as a basic component of various nanodevices. Nanowire joining is one of the crucial operations in micro-nano manufacturing. Compared with other joining methods, such as electrical current heating and mechanical pressure, laser illumination can yield metallic contacts through local precision nanosoldering. In this paper, the authors report the joining of one single copper nanowire (CuNW) to a silver film by a laser illumination method. They first cut the silver film on a flexible substrate to form a gap of about 1–4 μm by a 1030 nm femtosecond (fs) pulsed laser. Then, they coat CuNWs by dripping nanowire solution onto the gap, bridge the gap, and then join single CuNW with the fs pulsed laser. By comparison with scanning electron microscope images after and before laser illumination, it is found that the local silver film melts, then wraps partial CuNW, and finally crystallizes. So, the joining is through a part of CuNW embedded in a silver film. In addition, the authors further analyze the joining situation by directly measuring the resistance variation between after joining (Ra) and before joining (Rb). It is demonstrated that the resistance ratio of Ra to Rb decreases from 0.835 to 0.172 with increasing laser power from 10 to 40 mW for 3 s of the laser illumination time. The resistance ratio of Ra to Rb decreases from 0.936 to 0.368 with an increment of the laser illumination time from 1 to 4 s at a laser power of 30 mW. Finally, the authors find that the welded single CuNW enables sensing of glucose at a concentration of 10−5M.