Microsystems & Nanoengineering最新文献

The precise measurement of pH variations is pivotal across scientific and industrial domains, with colorimetric pH sensors gaining prominence for their simplicity and advantages over electrochemical alternatives. However, their widespread adoption has been hindered by challenges such as dye leaching, limited long-term stability, and a narrow dynamic range (typically ~3 pH units). To address these constraints, we engineered nanopigments by covalently bonding sulfonephthalein dyes to raspberry-like silica nanoparticles (RSNs), which were subsequently embedded within an agarose/polyethylene oxide (PEO) matrix to create stable, non-leaching pH-sensing films. To further expand the detection range, we integrated two distinct sulfonephthalein nanopigments-Bromocresol Green and Phenol Red into the matrix, leveraging their complementary pH sensitivities. CIELAB color space analysis revealed a synergistic interplay within the RSN-agarose-PEO microenvironment, driving multiple protonation and deprotonation events that extend the sensor's operational range to pH 1-10 with a uniform linear response. The versatility of the nanopigments was demonstrated by coating them onto various substrates, where they maintained robust pH responsiveness. This innovative strategy yields a durable, colorimetric pH sensor that overcomes the limitations of conventional systems, offering a practical, wide-ranging tool for applications in research, industry, and beyond.

Droplet-based microfluidics has witnessed tremendous progress in the past two decades, and this technique has been demonstrated as one of the most promising technologies to synthesize high-end and versatile materials with advanced functions, which provide great possibilities for numerous applications. Herein, the recent progress in preparing high-value natural microspheres by droplet-based microfluidic techniques is summarized comprehensively. We start with an in-depth articulation of the working principles of droplet-based microfluidics and surface modification for microdevices. Subsequently, droplet-based microspheres' fabrication methods have been discussed and summarized. Furthermore, the emerging representative biomedical applications of the different types of natural microspheres are outlined systematically. After that, we consider the challenges that hinder droplet-based microfluidic improvement in academic and industrial applications. Eventually, we will point out the perspectives of droplet-based microfluidics and aim to advance droplet-based microfluidics and sophisticated applications. The scope of this review is not only to offer an in-depth understanding of droplet-based microfluidics but also to open new pathways for versatile applications.

Through glass via (TGV) has emerged as a critical solution for next-generation packaging platforms owing to its low dielectric loss, superior coefficient of thermal expansion (CTE) compatibility. Previous studies shows that low thermal conductivity of TGV could lead to thermo-mechanical failures. However, current research on failure behavior of TGV induced by thermal stress structures remains relatively limited. This paper investigates the effects of annealing conditions on residual stress distribution and Cu protrusion behavior in TGV. The evolution of residual stress in top surface of glass substrates under different annealing temperatures and annealing periods was analyzed by nanoindentation, and the corresponding morphological changes of Cu protrusions were characterized by atomic force microscopy (AFM). It is found that annealing helps reduce residual stress on the glass substrate, but prolonged annealing can lead to the generation of residual tensile stress, thereby causing glass cracking; Cu protrusion height increases with annealing period but shows a decreasing growth rate. A creep rate model is established, achieving a RMSE of 1.143 for TGV creep behavior. A quantitative correlation model for the liner relationship residual stress and the Cu protrusion height is proposed. These results provide theoretical guidance for TGV reliability assessment and thermal optimization design.

Cardiovascular diseases remain the leading global cause of mortality and disability, posing a major challenge to human health. Accurate, long-term monitoring of electrophysiological activity in excitable cells such as cardiomyocytes is critical for elucidating disease mechanisms, advancing drug discovery, and evaluating therapeutic efficacy. However, conventional techniques each present key limitations: patch clamp offers high-fidelity signals but is invasive and low-throughput; optical imaging enables parallel measurements but is hindered by phototoxicity and limited temporal resolution; and planar microelectrode arrays support long-term studies but yield only low-fidelity extracellular recordings. To address these trade-offs, three-dimensional bioelectronic interfaces constructed from low-dimensional nanomaterials have recently emerged as powerful tools, providing minimally invasive, high-throughput, high-signal-to-noise intracellular recordings. Among them, one-dimensional nanostructures such as nanowires, nanopillars, and nanotubes offer unique advantages, including tight membrane coupling, tunable physicochemical properties, and compatibility with large-scale microfabrication. This review summarizes bottom-up synthesis strategies for these nanostructures, top-down and hybrid approaches for device integration, multimodal characterization methods, and intracellular access techniques. Finally, we highlight recent advances in cardiac electrophysiology, covering the fundamental principles of action potential generation and network propagation, as well as key applications in drug cardiotoxicity screening and disease modeling. Future directions are also discussed, including integration with complementary metal-oxide-semiconductor technology, development of flexible platforms, and in vivo bioelectronics.

This study presents a high-precision wireless displacement monitoring microsystem that utilizes the tunnel magnetoresistance (TMR) effect for structural health monitoring (SHM). The system overcomes limitations of traditional SHM methods, providing high-precision, intelligent and lightweight measurements. We established an analytical model of magnetic field displacement and optimized its linear range. Considering the measurement error caused by magnetic field decay, we designed an adaptive sensitivity correction method, thus avoiding the tedious magnetic field numerical fitting process. The system's accuracy and stability are validated through comparison with laser ranging, showing high accuracy within the range of ±7.5 mm, a resolution of 0.4 μm, and a long-term working accuracy better than 2.25 μm. The core system is less than 3.84 cm³ in size and is inexpensive to manufacture, making it ideal for mass deployment across a broad range of infrastructure. This work outperforms other state-of-the-art methods in the field in terms of accuracy, cost, size, and power consumption. Practical applications in monitoring concrete deformation, crack width changes, and bridge beam end slip deformation highlight its versatility and effectiveness. Its stable performance in long-term autonomous operation has also been verified in a 39-day actual bridge test, making it a valuable tool for enhancing infrastructure maintenance and safety.

'Light-mills' are optically driven microstructures that can exchange orbital angular momentum with light and thus rotate around a central axis with a controlled applied torque. Although many studies have explored the employment of light momentum for torque generation, only a few convincing applications in cellular and molecular biology have been demonstrated. Here, we design a 3D chiral structure that can be selectively coupled to a target nanometric flagellar motor in a live E. coli cell, functioning as an external, tunable torque clamp. We optimize our 3D microstructures for torque conversion efficiency and mechanical stability, and propose a calibration protocol that enables absolute quantification of the torque generated by the flagellar motor during rotation in both its natural and reverse directions. Our results demonstrate that microfabricated light-mills expand the optical toolbox for biomechanical study of individual rotary motors by enabling controlled torque application and measurement at the nanoscale.

Establishing robust pharmacokinetics-pharmacodynamics (PK-PD) correlations remains a major challenge owing to high selectivity and low permeability of the blood-brain barrier (BBB), which limits the predictive power of conventional plasma pharmacokinetics on specific brain tissue. Here, we present a highly biomimetic microfluidic BBB-brain organ-on-a-chip combined with liquid chromatography-mass spectrometry (LC-MS) and electrochemical sensing technology for micro PK-PD monitoring with target cells. The platform incorporates human cerebral microvascular endothelial cells and neuron-like cells cultured on opposite sides of a collagen/fibronectin-modified porous membrane under physiological shear stress. This configuration reinforces the physical, metabolic and physiological barrier functions of BBB, as evidenced by the high expression of tight junction proteins, low apparent permeability, expression of efflux transporters, and reversible response to hypertonic stimuli. A neurodegenerative disease model is induced using 1-methyl-4-phenylpyridinium iodide (MPP⁺) to recapitulate key pathological features of early-stage Parkinson's disease. The pharmacokinetic profile of pramipexole (PPX) is monitored using both LC-MS and an integrated, regenerable electrochemical sensor. The sensor enables in situ, real-time and online detection of PPX with high sensitivity and specificity, showing strong concordance with LC-MS. Furthermore, neurotransmitter (norepinephrine) exocytosis level is quantified as a pharmacodynamic indicator, enabling micro PK-PD correlation within the disease-on-a-chip model. Collectively, the proposed new method for micro PK-PD study is expected to provide great prospects for the preclinical screening and action mechanism research of novel anti-Parkinson's disease drugs.

Surface acoustic wave radio frequency identification (SAW RFID) has gained widespread adoption in remote sensing and identification. However, conventional SAW RFID tags suffer from significant energy loss due to the inherently low reflectance of standard reflectors, fundamentally limiting their wireless interrogation range. To address this limitation, this paper proposes a novel SAW RFID architecture employing reflective multistrip couplers (RMSCs), which exploit the velocity difference between symmetric and antisymmetric wave modes to achieve coherent reflection, thereby circumventing conventional electrical or mechanical reflection mechanisms. Numerical simulations were conducted to analyze performance deterioration induced by parasitic resistances and capacitance and to identify the optimal strip number for peak reflectance. The fabricated RMSC reflector achieves a low loss of 1 dB, with a reflectance difference of merely 0.33 dB compared to the simulation results. A 433 MHz SAW RFID prototype implementing RMSC reflectors on a 128°YX-LiNbO₃ single-crystal substrate demonstrated a -10.63 dB peak time-domain amplitude at room temperature, representing a substantial improvement over conventional designs. Temperature characterization from -20 °C to 90 °C revealed linear functions in time delay and phase responses, with coefficients of determination (R²) exceeding 0.9999. These results validate the RMSC reflector as a high-reflectance solution for enhancing SAW RFID performance, suggesting significant potential for long-range wireless sensing applications.

The reliability of through-glass via (TGV) interconnects is critical for advanced semiconductor packaging. This work investigates microstructural and mechanical evolution in electroplated TGV-Cu subjected to long-term aging at 250 °C. TGV samples were fabricated via laser-induced etching and double-sided copper electroplating, then aged for up to 1008 h. Nanoindentation revealed region-dependent reductions in hardness (from 2.0-2.5 GPa to below 0.5 GPa) and modulus (from 110-130 GPa to 40-90 GPa), with surface-near regions most affected. The glass substrate maintained stable mechanical properties until microcracks formed after 1008 h. EBSD quantification showed grain-size enlargement from 0.46 µm to 1.86 µm and a concurrent decrease in dislocation density. Molecular dynamics simulations of 3, 4, 5 nm grains corroborated the inverse relationship between grain size and micro-mechanical properties. A hybrid Potts-phase field model further linked grain coarsening to stress relaxation and elastic-energy minimization, revealing that as grains grow, the overall von Mises stress in the structure decreases; high-modulus grains retain relatively higher local stresses, while low-modulus, low-stress grains exhibit faster growth rates. Electrical I-V measurements confirmed stable ohmic behavior, despite a drop in insulation resistance. These integrated experimental and computational insights provide theoretical guidance for optimizing TGV interposer design and ensuring long-term operational reliability in heterogeneous integration technologies.

Surface plasmon resonance (SPR) biosensoris a new type of high sensitivity, real-time, label-free detection technology, which plays an increasingly important role in the biomedicine field. Considering the urgent requirement of trace detection, especially for diagnosing early-stage diseases, the demand for high detection sensitivity of sensors is increasing. In recent years, various nanostructures have been proposed to design SPR biosensors. By constructing composite nanostructures, the detection sensitivity has been significantly enhanced, which has become a promising solution to expand the application of SPR biosensors. This review systematically summarized the basic principle, fabrication and illustrative application of SPR biosensors based on versatile nanostructures. Firstly, the mechanisms of various nanostructures to enhance the detection sensitivity of SPR biosensors were clarified. Then, the preparation strategies of various nanostructures were comprehensively illustrated. In addition, this review also summarized the latest applications of SPR biosensors with different structures. Finally, this review carefully highlighted the current challenges and possible development directions in future.