Microsystems & Nanoengineering最新文献

Controllable droplet manipulation is essential for applications from biochemical analysis to soft robotics. Despite significant advances, existing methods struggle to achieve broadly tunable, asynchronous control of multiple droplets, limiting their efficiency in three-dimensional and dynamic environments. Here, we introduce a droplet ultrasonic tweezer (DUT), which leverages broadly tunable acoustic control to enable three-dimensional multi-droplet manipulation and enhance condensing surface renewal. The DUT generates a twin-trap acoustic field from a single phased-array focal point, allowing droplet coalescence and confinement at five specific trapping positions. Leveraging this capability, we demonstrate synchronous directional transport of three droplets and asynchronous control of their relative positions. Moreover, the DUT's vertically extensible twin trap enables synchronous manipulation of droplets across double-layer surfaces. Beyond transport, programmable spatial modulation of the acoustic field enhances microdroplet coalescence and suppresses merged-droplet detachment, increasing the droplet detachment size and expanding the swept area for more effective surface renewal. Our results establish a robust paradigm for applications in optical surface self-cleaning, condensation heat transfer, and atmospheric water harvesting, offering a scalable solution for precise droplet control.

Despite its huge potential, such as in biomedical research for bioparticle sorting and sensing, near-field optical trapping suffers from limited trapping efficiency due to the weak evanescent field accompanied by shallow penetration depth (~100 nm). Moreover, such optical trapping approaches are susceptible to perturbations from trapped particles, making them less robust and impractical. Here, we demonstrate, for the first time, a thin-walled hollow microbottle resonator with gradient-wall thickness to realize large-scale and robust optical trapping based on mode field strength antinodes, instead of the evanescent field. The microbottle resonator combined with off-equatorial fiber taper coupling collaboratively enables the excitation of axial high-order Whispering Gallery Modes (WGMs). In addition, the unique feature of the gradient-wall thickness design mitigates the adverse impact of the perturbation from trapped particles on mode field distributions, making the gradient-thickness protected (GTP) microbottle resonator more robust and stable. This enables large-scale optical trapping over an axial span exceeding 195 μm, with a threshold power of 0.198 mW for 500-nm-radius polystyrene particles. The GTP WGM microbottle resonator also achieves tunable localized optical trapping. This work demonstrates a scalable optical manipulation framework for applications in single-particle analysis, bioparticle manipulation, and label-free sensing.

Xuan paper (also known as Chinese rice paper), traditionally used for calligraphy and painting, has rarely been explored as a functional material. In this study, Xuan paper is repurposed for the first time as a humidity-sensitive material, exhibiting state-of-the-art sensitivity over a wide humidity range. A humidity sensor with a thickness below 0.09 mm and a mass below 0.012 g was fabricated using only Xuan paper, sodium chloride (NaCl) aqueous solution, and conductive carbon ink through a simple three-step process. Characterization of the sensor shows that NaCl crystals are combined with sparse cellulose fibers, facilitating moisture absorption and forming an electrochemical sensing system. To investigate the electrochemical properties of the sensor, electrochemical impedance spectroscopy was measured. The results reveal a transition in the conduction mechanism across a wide relative humidity range (11-97%), with an output variation as high as 2.65 × 10⁴ times. The large output variation enables easy readout without sophisticated circuits, paving the way for versatile applications. To enable humidity readout and wireless transmission, a flexible eight-channel readout circuit was developed based on a microcontroller (Arduino). The readout circuit and supporting smartphone application facilitated the practical tests of the humidity sensor, demonstrating its capabilities in environmental humidity monitoring, humidity-based touch sensing, urination monitoring, and motion state detection. This study attempts to address the longstanding trade-off between high performance and complex fabrication processes in humidity sensors and reveals the potential of Xuan paper as a functional material.

This narrative review evaluates the suitability of conventional biopolymer-based microencapsulation strategies, originally developed for facultative and aerotolerant probiotics, for the protection and delivery of extremely oxygen-sensitive (EOS) next-generation probiotics (NGPs). With increasing interest in NGPs, there is a pressing need to establish whether conventional formulation approaches can be effectively translated for these highly oxygen-sensitive bioactives. We reviewed commonly used microencapsulation materials and techniques, assessing their suitability and potential to preserve EOS bacterial viability. Hydrated pectin- and gellan-based microcomposite systems, particularly when combined with xanthan gum or other polymers, exhibited the strongest oxygen-protection performance. In contrast, alginate alone demonstrated inconsistent barrier properties, though its performance improved when blended or coated with chitosan. Dehydrated microcomposite systems did not yield additional viability benefits compared to their hydrated counterparts. Importantly, none of the studies explicitly quantified oxygen exposure parameters or established threshold levels required for effective protection of EOS strains. Despite some microcomposite systems demonstrating potential for EOS colonic delivery, our findings highlight a critical gap in formulation science for these sensitive bioactives and underscore the need for the development of bespoke, tailored delivery systems that advance beyond conventional approaches designed for facultative or aerotolerant strains. Addressing these gaps will support the advancement of microencapsulation technologies, improve biotherapeutic NGP formulation, and ultimately facilitate the translation of exploratory clinical findings into rationally designed, accessible, and effective microbiome-based interventions.

The strategic integration of micro/nano-engineering with controlled optical responses is pivotal for advancing solid tumor therapy. We have constructed a biomimetic nanosystem via the precise encapsulation of a flexible-chain iridium complex (IrC8) within giant plasma membrane vesicles (GPMVs) derived from tumor cells. This micro/nano-scale design leverages the endogenous structure of GPMVs to achieve superior biocompatibility and enhance homologous targeting, resulting in a 4.7% increase in cellular uptake compared to the free complex. The encapsulated IrC8 complex serves as a highly efficient photosensitizer, exhibiting a strong optical response characterized by an aggregation-induced emission enhancement factor (I/I₀) > 10 and a high singlet-oxygen quantum yield (ΦΔ = 0.18). Upon photoactivation, this system generates reactive oxygen species (ROS) with an 18-fold increase in yield, leading to potent phototoxicity with over 90% tumor cell apoptosis. Furthermore, the systematic integration of the vesicular carrier and the photosensitizer initiates a cascade reaction: the photodynamic effect not only directly eradicates tumor cells but also triggers immunogenic cell death (ICD), leading to potent immune activation. This synergistic combination of targeted delivery, photodynamic therapy, and immune stimulation within a single nanosystem demonstrates a remarkable synergistic therapeutic effect against solid tumors.

Fluidics on the micro- and nanoscale have been revolutionary for the fields of biology and medicine, and they are gaining a strong foothold in chemistry with the rise of micro and nanoscale reactors. These systems are based on fluidic platforms crafted into polymer or silicon-based substrates, and are comprised of channels with different functions and sizes that span from the micro- to the nanoscale. However, to fully capitalize on the possibilities offered by such highly integrated fluidic systems, the periphery that connects the fluidic chip to the macroscopic world, and thereby makes it accessible for the envisioned functions and applications, is equally important but receives much less attention. Such periphery needs to be versatile and enable accurate control of pressures and flow of liquids or gases, of sample temperature, and for certain applications even electric fields. Here, we report the development of a temperature-controlled fluidic chip holder for heating and cooling that is integrated with electrodes for the creation of electric fields across the fluidic system. It interfaces 1 cm² silicon-based nanofluidic chips with up to 12 fluidic connection points and optically transparent lid, that makes them compatible with optical microscopy techniques. We demonstrate the different functionalities of the sample holder by using nanofluidic scattering spectroscopy (NSS) to monitor the on-chip mixing of two different dyes, the diffusion of fluorescein into water at different temperatures, and the diffusion of fluorescein into water at different strengths of an electric field applied along a nanochannel.

Over the past two decades, silica-based nanobiomaterials (SNs) have emerged as a promising frontier in regenerative medicine, garnering substantial interest for their potential applications. Despite this growing interest, a notable lack of comprehensive and dynamic analyses remains, examining the evolution, development trends, research hotspots, and prospects of SNs in this field. To address this gap, we systematically analyzed 853 research articles published between 2006 and 2025 in the Science Citation Index Expanded (Web of Science Core Collection). Using bibliometric tools-CiteSpace, VOSviewer, and Biblioshiny-we generated data-driven visualizations to elucidate publication trends, contributions by countries/regions and institutions, journal distributions, research categories, thematic focuses, reference networks, and keyword dynamics. Our findings reveal a rapid acceleration in research output. While China leads in academic output volume, the United States maintains a significant advantage in average citation frequency, highlighting disparities in research impact. Current research hotspots include drug delivery systems, antimicrobial activity, bone regeneration, and wound healing. Keyword burst analysis identifies emerging frontiers such as mesoporous bioactive glass nanoparticles, wound healing, and zinc ion dopants. This study not only maps the trajectory of SNs in regenerative medicine but also discusses critical challenges and future directions, offering valuable insights for advancing the field.

Current carbonaceous fibers with 0.3-7 GPa tensile strength are ideally crystallized towards graphitized carbon nanowires for highly mechanical and conductive properties. An essential approach for this case is being challenged by the formation of graphitized carbon microstructures and the reduction of size to the nanoscale in the fabrication of carbonaceous fibers at a low temperature (1000 °C) that the chip can withstand without melting. Here the method for orienting carbon molecular chains in carbon microstructures is developed by chemical modification of polymer structure, conformational structuration of polymer molecular chains and axial orientation of carbon molecular chains. Using this method, carbon molecular chains are nearly all oriented along the axial directions, but are entangle in very small amounts. Our results demonstrate the presence of graphitized carbon microstructure in the carbon nanowires integrated with microstructure-based chips. We find that the graphitized nanowires exhibit unexpected tensile strength up to 24.74 GPa while having superior modulus and highly electrical conductivity up to 501.06 GPa and 1.16 × 10⁵S/m, respectively. The ability to synthesize patternable graphitized carbon nanowires on micro-pillars and micro-scaffolds of chips creates opportunities for research into correlated carbon microstructure and chip-based superior performances that are dependent on the nano-scaling and graphitizing of carbonaceous fibers.

Placental vascular anastomoses are a relatively common occurrence in monochorionic twin pregnancies, potentially leading to unbalanced blood supply to the developing twins, higher rates of perinatal mortality and long term morbidity. Unfortunately, our understanding of these conditions and their treatment strategies remains limited due to the lack of suitable in vitro and vivo twin models. Herein, we presented a microfluidic-based Monochorionic-Twin-on-a-Chip (MTOC) model designed to simulate monochorionic diamnionic (MCDA) pregnancies. The aim was to model the impact of an unbalanced nutrition supply on fetal organ growth using hepatic cells grown in vitro. Our findings confirm that an unbalanced nutrition supply from the donor circulation reduces cellular growth relative to the recipient system. This recapitulates the situation of the smaller (donor) and larger twins (recipient) within an MCDA pregnancy in vivo. Furthermore, hepatic cells exposed to the donor circulation exhibited a relative hypoxia state. Metabolite profiling of intracellular, extracellular, and biomass samples from small twins revealed lower levels of amino acids, fatty acids, and TCA cycle intermediates compared to large twins. Additionally, ¹³C metabolic flux showed upregulation of TCA cycle activity in the large twin, whereas the small twin would utilize more glutamine for energy supply and lipid synthesis. These results suggest that the unbalanced nutrient supply associated with some MC twin pregnancies restricts fetal liver growth in association with altered metabolic profiles. Moreover, our MTOC model represents a novel system for studying a range of other physiological intrauterine environments and pregnancy outcomes associated with MC twin pregnancies.

Infrared (IR) gas sensors have an urgent demand for high-reliability MEMS IR emitters. In this study, a wafer-level self-packaged MEMS IR emitter (SPIRE) has been designed and manufactured to enhance the durability of devices in high temperatures and ambient air. In the state-of-the-art design, Pt-wire heating and temperature sensing elements were fabricated onto a silicon (Si) membrane and vacuum-sealed within a glass cavity utilizing the Si-glass anodic bonding technique. Additionally, a black-Si nanostructure was prepared on the opposite side of the Si membrane to enhance IR light emissivity. The electrical-thermal-mechanical properties were simulated using COMSOL Multiphysics to optimize the structural design. The devices were fabricated through wafer-level MEMS processing techniques. Testing results demonstrated that the SPIREs were capable of achieving a light-emitting power intensity of 172 mW/Sr/µm at a peak wavelength of 6.1 µm and a 3-dB bandwidth of 52 Hz, corresponding to a surface temperature of 400 °C at a driving power of 850 mW. Long-term reliability was assessed through an accelerated aging test and a life prediction method. The estimated lifespan of the SPIREs can reach 10 years at a working temperature of 500 °C.