Microsystems & Nanoengineering最新文献

Spatial organization is fundamental to tissue physiology, as it governs how cells migrate, grow, differentiate, and interact within their native environments. In living tissues, cells are positioned within finely tuned microarchitectures defined by chemical gradients, boundaries, and mechanical cues - features that are essential for proper tissue function and homeostasis. Microphysiological systems (MPSs) aim to replicate key aspects of human tissue in vitro, yet without appropriate spatial control, they often fail to reproduce certain aspects of tissue-level organization and function. In this review, we categorize spatial patterning strategies into two main approaches: direct methods, which involve the physical placement of cells or compartments using techniques such as 3D bioprinting, microfluidic compartmentalization, and physical trapping; and indirect methods, which rely on cellular responses to engineered environmental cues, including extracellular matrix (ECM) composition, mechanical gradients, and soluble factor distributions. While direct methods offer precision and reproducibility, indirect strategies more closely reflect natural developmental and self-organizing processes. We discuss how these approaches are applied across diverse biological structures, from cellular interfaces and barrier tissues to dynamic host-microbe systems. Enhancing spatial fidelity in MPSs is essential for recapitulating tissue complexity, and will be key to advancing disease modeling, developmental biology, and drug screening applications.

Deep reactive ion etching (DRIE) is critical for fabricating high-aspect-ratio structures in microelectromechanical systems (MEMS), yet its complex, parameter-dependent process poses significant optimization challenges. Artificial intelligence (AI) offers an efficient optimization solution, but its implementation faces the technical challenge of acquiring large-scale data from scanning electron microscopy (SEM) images, the standard for evaluating DRIE etching outcomes. Traditional SEM analysis relies on labor-intensive manual methods, incurring 15-20% errors and hindering high-throughput manufacturing. Existing automated methods, such as CNNs and SVMs, falter with 70-80% accuracy in noisy SEM images, failing to capture the dynamic evolution of etched structures. To address these limitations, we propose a physics-constrained variational level set autoencoder (VLSet-AE) for automated SEM sectional-profile analysis. By integrating physical etching constraints and a three-dimensional framework (time, linewidth, etching depth), VLSet-AE achieves precise contour recognition and nine critical dimensions extraction-scallop depth (2.29%), scallop width (peak-to-peak: 2.05%, valley-to-valley: 6.28%), scallop radius (4.69%), profile angle (0.56%), trench depth (5.46%), bow width (4.35%), mid width (2.43%), and bottom width (4.78%)-with an average error of 3.65% an overall model accuracy of 94.3%, significantly outperforming manual annotation and state-of-the-art alternatives. Compared to seven current models (e.g., CNNs, LSTMs, ResNet), VLSet-AE achieves the shortest training time (20 s), fastest inference time (1.2 s), highest recognition accuracy (96%), and competitive memory usage (50 MB) and parameter count (4.0 million). By enabling efficient, large-scale data acquisition for AI-optimized DRIE processes, VLSet-AE empowers scalable, intelligent manufacturing, unlocking the potential for advanced microfabrication technologies. This approach provides a forward-looking framework for AI-driven MEMS process design and manufacturing, delivering innovative solutions for future AI-assisted microfabrication advancements.

Accurate detection of gene subtypes with high sequence similarity is critical for pathogen diagnosis. Current CRISPR-based PCR diagnostics methods may provide improved specificity but rely on pre-amplification in a separate reaction, due to Cas protein thermal instability, increasing cross contamination. Here, we developed CRISPR-based terminal-specific amplification (CASTSA), a one-pot platform which makes use of the CRISPR-Cas12a specific recognition and cleavage, generating a single strand digested product with specific 5' termini, to serve as the template for qPCR amplification. Our assay simplifies sample preparation by eliminating the need pre-amplification, whilst simultaneously fully exploiting the high specificity of the CRISPR system and high sensitivity of PCR. CASTSA was validated in vitro and with clinical samples collected from individuals with Human Papillomavirus (HPV), demonstrating high specificity for HPV 16, whilst discriminating HPV 18, 33, 45, and 52 sub-types, using a laser-induced graphene (LIG)-based electrochemical sensor platform. The technique achieved a limit of detection of 18 copies/reaction and offers a robust and reproducible, one-pot solution for pathogen subtyping, providing excellent specificity, so advancing nucleic acid detection with an assay that is easier to implement when compared with standard clinical diagnostic workflows.

In this study, alumina/CQD (carbon quantum dot) nanostructures are synthesized using varying concentrations of CQD solution to systematically investigate their structural, morphological, and optical characteristics. X-ray diffraction (XRD) analysis shows a gradual transition from a crystalline to an amorphous structure with increasing CQD content used through the synthesis process. For the samples with lower values of CQD content (AQD-1 and AQD-7), the calculated crystallite sizes by the Scherrer equation are 2.93 and 2.77 nm. In comparison, they cannot be calculated for the samples synthesized using higher values of CQDs (AQD-9 and AQD-13). The results indicate that the volume of the CQD solution notably influenced the nanostructure morphology and the distribution of CQDs in the produced nanostructures. Also, a notable dependence of the samples' optical properties on CQD concentration is observed. The indirect band gap energy of the nanostructures, in particular, demonstrates a systematic increase by increasing the CQD content, suggesting the tunability of the nanostructure's optical properties by adjusting the carbon concentration used in the synthesis process. The nanocomposites' specific surface area (SSA) decreased with increasing CQD concentration from 247.2 to 97.7 m²/g, suggesting partial pore blockage or aggregation induced by CQD incorporation. The synthesized nanocomposites exhibited high efficiency in the water treatment even in water containing high concentrations of copper ions (184 ppm), underscoring their potential as effective adsorbents for heavy metal remediation. These findings suggest promising prospects for developing multifunctional nanomaterials suitable for optical and environmental applications.

We present resonant mechanical systems that exploit diamagnetic levitation to eliminate clamping loss and achieve high quality factors at room temperature, toward enabling precision sensing applications. By engineering centimeter-scale composite plates formed by dispersing graphite microparticles in insulating epoxy and levitating them above arrayed permanent magnets, we demonstrate stable, full levitation of composite devices with masses exceeding 1.5 grams. Simulations and experimental measurements confirm stable three-dimensional trapping. Suppression of eddy current damping allows the levitated resonators to reach quality factors exceeding 32,000 in moderately high vacuum (∼25 µTorr) at room temperature. Residual velocity measurements and closed-loop frequency tracking using a phase-locked loop reveal near-zero passive motion and exceptional frequency stability, with Allan deviation down to 1.5 × 10^-6 at 20 s averaging time, demonstrating excellent stability of the levitation system. Furthermore, the devices can readily operate as sensitive magnetometers. These findings position levitated graphite composite plates as a scalable, low-dissipation candidate platform for next-generation inertial sensors and high-performance resonant systems.

Deterministic Lateral Displacement (DLD) is a high-precision microfluidic technique for particle separation based on size differences. However, the lack of an accurate predictive model for the critical diameter (Dc) limits both the design flexibility and understanding of DLD behavior. In this study, we propose a novel Dc prediction framework based on a 3D physical model, achieving high accuracy and computational efficiency. Experimental validation shows excellent agreement between predicted and actual particle trajectories. Remarkably, we discover that Dc exhibits a U-shaped variation along the vertical direction of the DLD channel, revealing a transition zone. Numerical simulations show that particles within this zone undergo vertical oscillations, causing trajectory switching between zigzag and bump modes, resulting in an altered zigzag trajectory. This framework reveals the mechanism behind altered zigzag formation from a 3D perspective and provides a powerful tool for the rapid, accurate, and customizable design of DLD microfluidic separation devices.

Inductive vibrating ring gyroscopes (IVRGs) present superior shock tolerance and reliability compared to conventional capacitive gyroscopes, making them ideal for inertial measurements in harsh environments. However, their operation in high-precision whole-angle mode requires real-time minimization of the frequency split between degenerate modes to prevent bias drift and measurement errors. Traditional electrostatic tuning methods are unsuitable for electromagnetic configurations, necessitating an alternative approach. In this paper, we propose and experimentally validate a localized thermal tuning technique to generate spatially controlled Joule heating at modal antinodes through specially patterned electrodes. This method utilizes the temperature-dependent increase of Young's modulus in fused silica to achieve reversible and real-time frequency adjustment, with minimal thermal coupling between the degenerate modes. Finite element simulations demonstrated that optimized electrode designs reduced thermal coupling coefficient and improved split tuning efficiency. Prototypes incorporating localized thermal electrodes were fabricated and characterized, achieving efficient frequency split suppression (reducing split to 14 mHz), substantial reductions in angle-dependent bias (from 0.928°/s to 0.146°/s), significant scale factor nonlinearity improvements (from 4321 ppm to 61.3 ppm), and enhanced bias instability (from 4.8°/h to 0.67°/h), all with negligible impact on quality factor and robust temperature adaptability across -40 °C to 60 °C. These results confirm that localized thermal tuning is an available and effective strategy for inductive vibrating ring gyroscopes, paving the way for enhancing the precision in harsh environment applications.

Wire-form shape memory alloy (WF-SMA) actuators have become integral components in numerous advanced applications ranging from robotics and aerospace to biomedicine thanks to their exceptional energy density, compact architectures and versatile actuation modes. Serving as a unique bridge between high-force actuation and material compliance, WF-SMAs enable the fabrication of intelligent soft materials and stretchable electronic systems. This work contributes a comprehensive and systematic assessment of WF-SMA actuators, including actuation modeling methodologies, typical actuator configurations, control strategies, and cutting edge applications in multiple fields. We firstly revisit the SMA actuation models with an emphasis on the theoretical foundation as well as current challenges in representing SMA's nonlinear, thermodynamic and actuation behaviors. Then, actuator design paradigms are classified according to the characteristic of the mechanical load (i.e. linear, nonlinear and differential) followed by briefly exploring the large-stroke strategies. Control approaches for manipulating WF-SMA systems are also surveyed covering a spectrum from conventional algorithms to smart strategies based on SMA-specific models, neural networks and integrated self-sensing methods. Drawing upon this assessment, we elucidate the key challenges that impede the widespread and practical application of SMA technologies, and suggest that future fabrication of WF-SMA actuators should increasingly rely on the integration of micro-nano fabrication techniques, flexible electronics, and multifunctional materials. Another promising direction for future research would be to prioritize the development of integrated modeling-design-control frameworks. Leveraging deep learning within the framework to navigate the complex nonlinearities of SMAs will directly improve operational performance and long-term reliability.

Nanomechanical resonators are increasingly becoming of interest across a range of applied and fundamental physics applications. Within many of these, the retention of bulk diamond's high Young's modulus, coupled with the compatibility with standard substrate materials, makes nanocrystalline diamond (NCD) particularly well suited for fabricating high-frequency devices. As device dimensions shrink in pursuit of ever-higher frequencies, however, dissipation from sources such as clamping and surface loss often becomes increasingly significant. To address this, a series of doubly clamped beams and clamping-loss-suppressing free-free resonator geometries were fabricated from both as-grown and chemically mechanically polished NCD. At 12 K, the free-free geometries curtailed the pronounced length-dependent loss seen in doubly clamped beams, reducing dissipation by up to 8.8× and achieving Q factors of the order of 10,000 from ~40 MHz to ~100 MHz. Minor differences in dissipation between devices fabricated from the as-grown and polished stock, meanwhile, suggest that surface-related loss is likely a minor contributor to dissipation at this temperature, contrasting with trends in alternative material counterparts. As such, the combination of NCD's apparent low surface-related loss and the loss-scaling suppression offered by free-free geometries provides a promising route to minimising dissipation in high-frequency nanomechanical resonators.