Micromachines最新文献

In recent years, the macro-micro structure (servo platform for macro motion and galvanometer for micro motion) composed of a galvanometer and servo platform has been gradually applied to laser processing in order to address the increasing demand for high-speed, high-precision, and large-format precision machining. The research in this field has evolved from step-and-scan methods to linkage processing methods. Nevertheless, the existing linkage processing methods cannot make full use of the field-of-view (FOV) of the galvanometer. In terms of motion distribution, the existing methods are not suitable for continuous micro segments and generate the problem that the distribution parameter can only be obtained through experience or multiple experiments. In this research, a new laser linkage processing method for global trajectory smoothing of densely discretized paths is proposed. The proposed method can generate a smooth trajectory of the servo platform with bounded acceleration by the finite impulse response (FIR) filter under the global blending error constrained by the galvanometer FOV. Moreover, the trajectory of the galvanometer is generated by vector subtraction, and the motion distribution of macro-micro structure is accurately realized. Experimental verification is carried out on an experimental platform composed of a three-axis servo platform, a galvanometer, and a laser. Simulation experiment results indicate that the processing efficiency of the proposed method is improved by 79% compared with the servo platform processing only and 55% compared with the previous linkage processing method. Furthermore, the method can be successfully utilized on experimental platforms with good tracking performance. In summary, the proposed method adeptly balances efficiency and quality, rendering it particularly suitable for laser precision machining applications.

This study presents a Hybrid Piezoelectric-Triboelectric Energy Harvester (HPTEH) composed of two coupled cantilever beams, designed to enhance energy generation and broaden bandwidth by combining piezoelectric and triboelectric mechanisms. A theoretical 2-DOF lumped model was developed and validated with experimental results, demonstrating good agreement. Experimental findings reveal that Beam I exhibits a softening effect, with resonance frequencies shifting to lower values and increased displacement amplitudes under higher excitation levels due to material nonlinearities and strain-induced voltage generation. Beam II, in contrast, displays a hardening effect, with resonance frequencies increasing as triboelectric interactions enhance stiffness at higher excitation levels. Coupling dynamics reveal asymmetry, with Beam I significantly influencing Beam II in the higher frequency range, while Beam II's impact on Beam I remains minimal. Phase portraits highlight the dynamic coupling and energy transfer between the beams, particularly near their natural frequencies of 18.6 Hz and 40.6 Hz, demonstrating complex interactions and energy exchange across a broad frequency range. The synergistic interplay between triboelectric and piezoelectric mechanisms allows the HPTEH to efficiently harvest energy across a wider spectrum, underscoring its potential for advanced energy applications in diverse vibrational environments.

In differential MEMS resonant sensors, a pair of resonators are interconnected with other structural components while sharing a common substrate. This leads to mutual coupling of vibration energy between resonators, interfering with their frequency outputs and affecting the sensor's static performance. This paper aims to model and analyze the vibration coupling phenomena in differential common-based MEMS resonators (DCMR). A mechanical model of the DCMR structure was established and refined through finite element simulation analysis. Theoretical calculations yielded vibration coupling curves for two typical silicon resonant accelerometer (SRA) structures containing DCMR: SRA-V1 and SRA-V2, with coupling stiffness values of 2.361 × 10^-4 N/m and 1.370 × 10^-2 N/m, respectively. An experimental test system was constructed to characterize the vibration coupling behavior. The results provided coupling amplitude-frequency characteristic curves and coupling stiffness values (7.073 × 10^-4 N/m and 1.068 × 10^-2 N/m for SRA-V1 and SRA-V2, respectively) that validated the theoretical analysis and computational model. This novel approach enables effective evaluation of coupling intensity between 5resonators and provides a theoretical foundation for optimizing device structural designs.

Chatter is a common phenomenon in micromachining processes that adversely affects machining quality, reduces tool life, and generates excessive noise that contributes to environmental pollution. Therefore, the timely detection of chatter is crucial for sustainable production. This paper presents an investigation on the extraction of two types of features, i.e., probability-related and entropy-related, using Shannon entropy and Rényi entropy algorithms, respectively, for chatter detection in micro milling. First, four chatter features were examined using actual machining tests under stable, weak-chatter, and severe-chatter conditions. Second, the proposed chatter features were systematically assessed by combining the characteristic change rates, threshold intervals, and computation times. The results demonstrated that the proposed features can effectively detect the occurrence of chatters at various severity levels. It was found that the probability-related features exhibit better sensitivity compared to entropy-related features, and the features extracted from Shannon entropy algorithm are more sensitive than the Rényi entropy algorithm.

The study introduces new technologies of microfinishing, which are primarily aimed at cylindrical surfaces but with machining effectiveness, precision, and surface longevity. In the newly proposed dual-zone microfinishing method, symmetrical abrasive film feeding systems are adapted with a lever mechanism and a pivoting pressing assembly to simultaneously conduct processing in two zones. With such a design, uniform force distribution is ensured, while mechanical deformation is reduced to raise the utility of the abrasive film and lower scraps for better economic performance. Also, the application of microfinishing operations combined with carbon layer deposition using graphite-impregnated abrasive films is introduced as a novel method. This process combines surface refinement and the forming of wear-resistant carbon coatings into one single operation, resulting in increased wear resistance and reduced forces of friction. Further stabilization of the conditions for microfinishing is achieved by immersing the processing zone in a fluid medium due to increased lubrication, improvement in heat dissipation, and the optimization of surface properties. It is particularly suitable for high-precision applications and a maintenance-free environment such as military, vacuum, and low-temperature systems. The experimental results show the effectiveness of the proposed methodologies, underscoring their ability to create remarkably smooth surfaces and very robust carbon textures simultaneously.

Three-dimensional printing is promising in the pharmaceutical industry for personalized medicine, on-demand production, tailored drug loading, etc. Pressure-assisted microsyringe (PAM) printing is popular due to its low cost, simple operation, and compatibility with heat-sensitive drugs but is limited by ink formulations lacking the essential characteristics, impacting their performance. This study evaluates inks based on sodium alginate (SA), hydroxypropyl cellulose (HPC H), and hydroxypropyl methylcellulose (HPMC K100 and K4) for PAM 3D printing by analyzing their rheology. The formulations included the model drug Fenofibrate, functional excipients (e.g., mannitol, polyethylene glycol, etc.), and water or water-ethanol mixtures. Pills and thin films as an oral dosage were printed using a 410 μm nozzle, a 10 mm/s speed, a 50% infill density, and a 60 kPa pressure. Among the various formulated inks, only the ink containing 0.8% SA achieved successful prints with the desired shape fidelity, linked to its rheological properties, which were assessed using flow, amplitude sweep, and thixotropy tests. This study concludes that (i) an ink's rheological properties-viscosity, shear thinning, viscoelasticity, modulus, flow point, recovery, etc.-have to be considered to determine whether it will print well; (ii) printability is independent of the dosage form; and (iii) the optimal inks are viscoelastic solids with specific rheological traits. This research provides insights for developing polymer-based inks for effective PAM 3D printing in pharmaceuticals.

La₃Ga₅SiO₁₄ (langasite, LGS)-based surface acoustic wave (SAW) devices are widely used for industrial health monitoring in harsh high-temperature environments. However, a conventional LGS-based SAW structure has a low quality factor (Q) due to its spurious resonant peaks. A hetero-acoustic layer (HAL)-based structure can effectively enhance the Q factor and the figure of merit (FOM) of SAWs due to its better energy confinement of SAWs. In this work, a HAL-based structure is proposed to achieve a high FOM and high-temperature resistance at the same time. Based on the finite element method (FEM) and coupling-of-model (COM) combined simulation, a systematic numerical investigation was conducted to find the optimal materials and structural parameters considering the viability of an actual fabricating process. After optimizing the layer number, an intermediate-layer material choice and structural parameters, Pt/(0°, 138.5°, 27°) LGS/YX-LGS/SiC HAL structure were chosen. The proposed structure achieves a Q factor and FOM improvement of more than 5 and 2.6 times higher than those of conventional SAW structures, which is important for the development of high temperature SAW sensors. These findings pave a viable method for improving the Q factor and FOM of LGS-based SAW and can provide material and device structural design guidance for fabrication and high-temperature applications in the future.

We present a MEMS array-based approach for micro-irises called "ring shutter", utilizing subfield addressing for applications in advanced micro-optics, such as interference microscopy. This experimental study is focused on investigating the homogeneity of electro-mechanical and optical characteristics within and between subfields of a lab demonstrator device. The characterization aims to ensure crosstalk-free and swift optical performance, as demonstrated in a previous study. For this purpose, the transmission in the initial state, actuation voltages, and response dynamics are measured for each electrode and the entire device, and the results are thoroughly compared. The measurements are conducted by expanding an existing optical actuation setup via tailored 3D-printed apertures, to isolate selected rings and zones. Evaluation of measurement data confirms the stable and crosstalk-free operation of the ring shutter. Both angular and radial homogeneity are robust and follow the expectations in the experiment. While transmission, actuation voltage and closing time slightly rise (up to 25%) with increased radial position represented by five discrete ring sections, the characteristics for different angular zones remain nearly constant. Response times are measured below 40 µs, actuation voltages do not exceed 60 V, and the overall transmission of the ring shutter yields 53.6%.

Rapid and reliable detection of pathogens requires precise and optimized analytical techniques to address challenges in food safety and public health. This study focuses on the parametric characterization of an electrochemical aptasensor for Staphylococcus aureus (S. aureus) iron-regulated surface determinant protein A (IsdA) using cyclic voltammetry (CV) analysis, which offers a robust method for evaluating electrode modifications and electrochemical responses. Key parameters were optimized to ensure maximum sensitivity, including an aptamer concentration of 5 μM, an incubation time of 4 h, a potential range from -0.1 to 0.9 V, and a scan rate of 0.05 V/s. The aptasensor achieved stability and peak performance at pH 7.5 and 25 °C. These conditions were critical for detecting the IsdA protein as a biomarker of S. aureus. The aptasensor applicability was demonstrated by successfully detecting S. aureus in food samples such as milk and apple juice with high specificity and reliability. Zeta potential measurements confirmed the layer-by-layer charge dynamics of the AuNPs-aptamer-IsdA system. This work emphasizes the importance of CV in understanding the performance of the electrochemical sensor, and supports the aptasensor as a practical, sensitive, and portable tool for addressing critical gaps in foodborne pathogen detection.

Thin film microelectronic devices and circuits (TFMDCs), including thin film transistors (TFTs), thin film solar cells (TFSCs), thin film sensors (TFSs), thin film memories (TFMs), etc [...].