Microsystems & Nanoengineering最新文献

Plasmonic lattices offer a promising platform for overcoming the optical diffraction limit and suppressing radiative losses, which are crucial for advancing large-scale integration in nanophotonic devices. The performance of such integrated devices are strongly influenced by the arrangement and unit geometry of plasmonic lattices, highlighting the need for precise and scalable fabrication strategies. Here, we systematically design and fabricate a series of plasmonic square lattices with decreasing unit symmetries, from C_∞v (O-hole) to C_4v (X-hole) and C_s (OX-hole). The polarization-resolved emission intensities at high symmetry points are thoroughly investigated, revealing a 45° deflection in the polarization angle at Γ⁽¹⁾ as the structural symmetry decreased, while the other four high symmetry points, X⁽¹⁾, M⁽¹⁾, Γ⁽²⁾, and X⁽²⁾, exhibited a 90° polarization shift. This tunability provides an effective approach for modulating the polarization characteristics of plasmonic lattices. The highest polarization degree of 0.59 was observed at the X⁽²⁾ point, where the energy matched the 720 nm emission of the Nile Red gain medium, resulting in directional and polarized amplified spontaneous emission under 532 nm optical pumping. This study establishes a framework for generating polarized amplified spontaneous emission at high symmetry points in plasmonic lattices, providing innovative strategies for tunable light sources in sensing and photonics communication applications.

Superconducting quantum computers have emerged as a leading platform for next-generation computing, offering exceptional scalability and unprecedented computational speeds. However, scaling these systems to millions of qubits for practical applications poses substantial challenges, particularly due to interconnect bottlenecks. To address this challenge, extensive research has focused on developing cryogenic multiplexers that enable minimal wiring between room-temperature electronics and quantum processors. This paper investigates the viability of commercial microelectromechanical system (MEMS) switches for cryogenic multiplexers in large-scale quantum computing systems. DC and RF characteristics of the MEMS switches are evaluated at cryogenic temperatures (<10 K) through finite element simulations and experimental measurements. Our results demonstrate that MEMS switches exhibit improved on-resistance, lower operating voltage, and superior RF performance at cryogenic temperatures. In particular, an engineered gate-pulse waveform is introduced to suppress beam bouncing caused by the quasi-vacuum conditions inside the package, enabling stable dynamic operation exceeding 100 million cycles even at cryogenic temperatures. Furthermore, stable single-pole four-throw (SP4T) switching and logical operations, including NAND and NOR gates, are demonstrated at cryogenic temperatures, validating their potential for quantum computing. These results underscore the promise of MEMS switches in realizing large-scale quantum computing systems.

Surface plasmon polariton probes have important applications in super-resolution imaging and sensing. However, conventional probes often rely on complex radially polarized light excitation and struggle to achieve high-intensity electric field enhancement localized at the probe tip, which limits their practical performance. This paper proposes a double-slit plasmonic platform-based fiber probe that enables efficient nanofocusing under linearly polarized light by integrating the Fabry-Pérot interference enhancement mechanism of the platform-based structure with the polarization control function of the asymmetric half-ring slit. We introduce an innovative sleeve ring etching technique that increases the probe tip curvature by more than an order of magnitude while also addressing the issue of uncontrollable morphology in conventional probe fabrication. Experimental results demonstrate that the proposed probe exhibits an electric field strength at the probe tip that is six times higher than that of an asymmetric double-slit probe at a wavelength of 633 nm. Furthermore, it maintains stable focusing across a broadband range from 580 nm to 800 nm, with particularly significant enhancement in the short-wavelength region. Additionally, this probe achieves a resolution of 28.6 nm in optical imaging experiments, enabling simultaneous characterization of both morphological and optical properties of deep subwavelength-sized samples under ambient conditions.

Cell transportation, using a micropipette to pick and place cells from one droplet to another, is a key step in many cell engineering applications. However, most of the current cell transportation operations rely on microscope vision guidance, unsuitable for the future integrated and automated cell engineering applications where microscopic views are usually missed. The presenting microscopic view-free cell transportation systems are only applicable for special giant cells due to the bilayer structure of operation micropipettes. In this paper, a robotic cell transportation system based on micropipette resistance modeling was developed to transport common-sized cells without a microscopic view. First, a narrow-necked micropipette (NNM) was fabricated for holding the target cell inside the micropipette during transportation. Then, a gap resistance model, an aspiration resistance model, and an injection resistance model of the micropipette were developed to land on the cell plane, pick and release the cell without a microscopic view, respectively. Based on the above work, a robotic transportation process was established to transport the common-sized cells without a microscopic view. Finally, experimental results demonstrate that the proposed system can land on the cell plane with 100% success rate. It can transport 10 μm-level sized HeLa cells and 100 μm-level sized porcine oocytes with efficiencies comparable to common microscopic view-based methods and without harm to cell survival rate. Our microscopic cell transportation system can be upgraded to a high-throughput version for integrated automated cell engineering applications in the future.

Wide-range and high-sensitivity hydrogen sensors are critically important for hydrogen safety in aerospace and advanced transportation sectors. This work demonstrates a thermal-conductivity surface acoustic wave (SAW) based sensor to achieve high sensitivity hydrogen sensing. By integrating thermal balance and acoustic wave equations, a precise mechanistic model elucidating the structure-activity relationships among gas flow rate, operating temperature, and MEMS architecture in determining sensing sensitivity is constructed. Guided by this model, the SAW hydrogen sensor with on-chip microheater integration was developed. Furthermore, a highly integrated SAW hydrogen sensing system with ultra-low baseline noise (<30 µV) was constructed for performance evaluation. Leveraging the exceptional thermal sensitivity of the SAW device and system stability, the optimized sensor achieves wide detection range (up to 100% vol), low detection limit (~6 ppm), rapid response and recovery time (T₉₀/T₁₀: ~15 s), excellent repeatability (error<2.4%) at a relatively low operating temperature (120 °C). The prepared SAW sensor provides an effective solution for hydrogen leakage monitoring across unprecedented concentrations (ppm-100% vol), establishing a new paradigm for hydrogen safety applications.

Skin aging results from a combination of intrinsic factors and exogenous stimuli, leading to changes in the structure and components of the extracellular matrix (including the skin basement membrane), which directly influence the aging process. In vitro models are powerful tools for exploring skin aging and overcoming inter-species differences and ethical issues associated with animal models, thus demonstrating powerful potential in skin aging research and anti-aging drug development. In this review, the advantages and disadvantages of in vitro models are discussed, including 2D monolayer models, 3D static reconstructed human skin models, 3D bioprinting models, organoid models, and Skin-on-Chip models for studying skin aging and anti-aging drug development. Finally, concepts and perspectives for the next-generation skin aging models are proposed. These models are expected to provide innovative tools for investigating the mechanisms of skin aging in depth, as well as skin aging repair and prevention.

A multi-modal neural interface capable of long-term recording and stimulation is essential for advancing brain monitoring and developing targeted therapeutics. Among traditional electrophysiological methods, micro-electrocorticography (μECoG) is appealing for chronic applications because it provides a good compromise between invasiveness and high-resolution neural recording. When combining μECoG with optical technologies, such as calcium imaging and optogenetics, this multi-modal approach enables simultaneous recording of neural activity from individual neurons and the ability to perform cell-specific manipulation. While previous efforts have focused on multi-modal interfaces for small animal models, scaling these technologies to larger primate brains remains challenging. In this paper, we present a multi-modal neural interface, named Smart Dura, a functional version of the commonly used artificial dura with integrated recording and stimulation electrodes for large cortical area coverage of the NHP brain. The Smart Dura is fabricated using a thin-film microfabrication process to monolithically integrate a micron-scale electrode array into a soft, flexible, and transparent substrate with high-density electrodes (up to 256 electrodes) while providing matched mechanical compliance with the native tissue and achieving high optical transparency (exceeding 98%). Our in vivo experiments demonstrate electrophysiological recording capabilities combined with neuromodulation, as well as optical transparency that enables structural and functional imaging. This work paves the way toward a chronic neural interface that can provide large-scale, bidirectional interfacing for multi-modal and closed-loop neuromodulation capabilities to study cortical brain activity in non-human primates, with the potential for translation to humans.

Microfluidic devices with ultra-fine features are critical for applications in biomedical diagnostics, chemical analysis, and lab-on-chip systems, but achieving high-resolution negative features with fast print times remains a significant challenge due to limitations in conventional 3D printing techniques. Motivated by the need for rapid fabrication of precise, compact microfluidic structures to enhance performance and miniaturization, we present an efficient multi-resolution 3D printing technique designed to fabricate microfluidic devices with exceptionally high-resolution negative features. For instance, we achieve fully enclosed channels with cross sections as small as 1.9 µm × 2.0 µm, a two-order-of-magnitude reduction in cross-sectional area compared to the 18 µm × 20 µm channels reported in our previous work (Gong et al., Lab Chip 17, 2899, 2017). Our method utilizes a dual-optical-engine approach comprising a Very High Resolution Optical Engine (VHROE) and a Main Optical Engine (MOE), each employing distinct pixel resolutions and LED wavelengths. The VHROE, with a pixel pitch of 0.75 µm and a 365 nm LED, delivers unparalleled resolution, while the MOE, with a pixel pitch of 15 µm and a 405 nm LED, ensures efficient coverage for larger areas up to 38.9 mm × 24.3 mm. Custom ultraviolet (UV) short-pass filters are used to tailor each LED spectrum, optimizing performance for each optical engine. Both engines are mounted on an XY stage to achieve multi-resolution imaging in the XY plane. Depth-wise (Z-axis) multi-resolution is achieved by formulating a photopolymerizable resin incorporating two UV absorbers possessing distinct absorption spectra such that the different light spectra from the VHROE and MOE encounter disparate levels of absorption, resulting in 1/e penetration depths of 2 µm and 20 µm, respectively. This enables true multi-resolution printing in all three dimensions. Our method balances speed and resolution by selectively deploying the VHROE for ultra-fine features and the MOE for bulk structures within a single 3D print. To demonstrate the versatility of this technique, we fabricated intricate microfluidic structures, including a triply-periodic minimal surface (TPMS) with 7 µm pores embedded within a 150 µm × 150 µm cross section enclosed channel, and an ultra-compact microfluidic mixer with a printed volume of only 0.017 mm³ (17 nL) and a print time of 21 minutes. These examples underscore the potential of our multi-resolution 3D printing method for advancing microfluidic device fabrication.

In recent years, micro-electromechanical systems (MEMS) actuators have emerged as innovative solutions for enhancing the dynamic control of terahertz devices, leveraging their advantages of miniaturization, low power consumption, and high integration. This paper provides a comprehensive review of the fundamental technological advancements in terahertz MEMS actuators, with a particular emphasis on the analysis of the performance characteristics of various driving mechanisms and the integration strategies. Furthermore, it systematically presents the diverse forms of terahertz MEMS actuators utilized in terahertz switches and tunable resonators, highlighting the significant advancements they have made in applications including sensing, frequency and polarization tuning, beamforming, and logical operations. By leveraging cutting-edge microfabrication techniques and functional materials, terahertz MEMS actuators are capable of achieving wideband tuning, high-sensitivity sensing, and the modulation of intricate electromagnetic responses. Additionally, the review examines prospective development trajectories, offering theoretical insights and technical strategies to support the transition of terahertz technology from laboratory settings to practical applications in domains such as 6 G communication, high-resolution imaging, and intelligent sensing.

In atomic force microscopy, sensitivity is one of the most important characteristics as in many measurement applications. Nevertheless, in literature different meanings of the terms sensitivity and resolution can be found. The same holds for the connectected quantity responsivity. Far more, there is no literature showing globally how different system and process parameters influence sensitivity. In this work we want to make a clear definition of these term in the context of AFM. Additionally, we present the global behavior of the AFM cantilever-sample system in terms of responsivity, noise, and sensitivity. An analytical model is derived that shows this system behavior. This is achieved by finding simple analytical equations for amplitude and phase as functions of the tip-sample distance assuming small amplitudes. Furthermore, the derived equations are scaled to reduce the amount of parameters and get a more generalized form. The scaled equations are analyzed to show the influence of system parameters like damping ratio, excitation frequency and sample parameters on the global system behavior. With that, parameter for best sensitivity can be found. For larger amplitudes where the analytical model is not valid, a numerical model solved with numerical continuation is used to gain further results showing the difference between non-contact and intermittent mode. For validation, we show experimental amplitude distance curves measured with a self-developed setup. This setup is a new possibility to measure amplitude distance curves in an open and flexible environment without the need of having a commercial AFM system.