ZUSAMMENFASSUNG Der Ionentransport an elektrisch polarisierten Grenzflächen wird traditionell durch die Umverteilung mobiler Ionen zur Wahrung der lokalen Elektroneutralität beschrieben. Unter Bedingungen starker räumlicher Begrenzung des Elektrolyten verliert diese Annahme jedoch ihre Gültigkeit, sobald die charakteristische Transportlänge in die Größenordnung der Debye‐Abschirmlänge gelangt. Dadurch entstehen Raumladungszonen und ein langsamer elektrostatischer Ladungsausgleich, die das kinetische Verhalten an der Grenzfläche maßgeblich bestimmen. Hierzu führen wir eine Interphase mit ortsfesten Ladungen ein, in der anionische Ladungsgruppen die mobilen Anionen des Elektrolyten selektiv als primäre ladungskompensierende Spezies ersetzen und so eine in der Chemie der Interphase verankerte, elektrostatische Randbedingung etablieren. Unter Verwendung eines zur Koordination von Kationen fähigen, glucosebasierten Netzwerks als Modellsystem zeigen wir, dass lokalisierte ortsfeste Ladungen den kationenselektiven Transport ermöglichen und ausgedehnte Raumladungsschichten durch die Eliminierung langsamer Relaxationspfade unterdrücken. Die Analyse des räumlich‐zeitlichen Transportverhaltens zeigt, dass diese Interphase die über mehrere Zeitskalen ablaufende Grenzflächenrelaxation in ein einheitliches kinetisches Regime überführt. Bei Anwendung auf elektrochemische Systeme mit räumlicher Begrenzung (Einschluss) auf Nanoliter‐Volumina (45 nL) wird der durch Ruhephasen verursachte Einbruch der Coulomb‐Effizienz von 40 % auf 5 % reduziert. Dies demonstriert eine Stabilisierung der elektrostatischen Relaxation während der Ruheperioden—eines für zyklisch betriebene Mikrosysteme intrinsischen Ausfallmusters. Das Konzept wird ferner unter pH‐gekoppelten sowie oxidativen Belastungsbedingungen validiert und zeigt einen stabilen Betrieb bei hoher Ratenfähigkeit. Diese Ergebnisse definieren eine allgemeine chemische Strategie zur Regulierung des Ionentransports and Grenzflächen unter räumlicher Begrenzung, indem mobile ladungskompensierende Spezies durch molekular gebundene, ortsfeste Ladungen ersetzt werden.

Biological systems seamlessly integrate energy storage and actuation within compact architectures, whereas synthetic approaches largely implement these functions as separate components. Conjugated polymers can couple both, yet their operation relies on ion insertion accompanied by hydration water within the polymer backbone, creating an intrinsic trade-off between performance and stability. Here we show that anion hydration governs this trade-off. In-operando Raman spectroscopy and time-resolved mass measurements reveal that reducing anion hydration suppresses water ingress, mitigates backbone degradation and converts the polymer response from a two-step swelling process into a single, rapid volumetric relaxation. Leveraging this principle, we realize a sub-millimetre monolithic device that integrates energy storage and actuation within a 0.56 mm2 footprint. A centrally configured dual-cell microbattery delivers 161 mAh cm-2 and reduces the energy consumption of surrounding actuators by fourfold. Hydration control, as the governing design parameter for multifunctional devices, holds translational promise for integrated energy-motion architectures at the microscale.

True microrobots, in contrast with externally controlled microparticles, must harvest or carry their own source of energy, as well as their own (preferably programmable) microcontroller of actuators for locomotion, using information acquired from their own sensors. We demonstrate here, for the first time, that microrobotic smartlets, hitherto buoyancy divers, can also be equipped to navigate in 2D on surfaces, with onboard control responding to both sensor information and their internal electronic program. Fabricating modular microrobots, with all dimensions of 1 mm and below, has been difficult to achieve because of competing demands for the limited surface area and the challenges of integrating and interconnecting the diverse functionalities of energy harvesting, actuation, sensing, communication, docking, and control. A novel high‐density heterogeneous integration, via soft‐substrate micro flip‐chip bonding of custom CMOS and LED microchiplets onto fold‐up polymer surfaces, compatible with roll‐up isotropic ambient light harvesting, now makes this possible. Fabricating electrolytic bubble actuators on multiple cube faces and connecting them to a custom sensor‐controlled onboard microchiplet (lablet) allow the smartlets to locomote on wet surfaces, changing direction in response to both timed programmed control as well as programmed response to locally sensed signals. Such locomoted robotic microcubes can also move to and selectively dock with other modules via patterned surfaces. This is powered by ambient light in natural aqueous media on smooth surfaces.

Microscopic robots (microrobots) with integrated electronic chips have a range of potential medical, environmental and industrial applications. However, such systems have only recently become mass-producible, using either a body-first or a brain-first approach to fabrication.

We present an experimental method to determine the refractive index of AlxGa1−xAs (x = 0.0–0.5) from 300 to 4 K across the 500–1100 nm wavelength range. The values are extracted from spectroscopically observed microcavity resonances in thin AlGaAs membranes embedded between fully and partially reflective gold mirrors. Refined Varshni and Paessler models are used to describe temperature-dependent bandgap shifts and material composition. By tracking resonance shifts and benchmarking against finite-difference time-domain simulations, we derive the dispersive optical response with high precision. This approach yields a quantitatively improved analytical expression for the refractive index n of AlGaAs, achieving modeling accuracy by a coefficient of determination of up to R2 = 0.993, at a maximal experimental uncertainty of Δn = 0.0647. Consequently, it enables accurate modeling in the vicinity of the band edge and revises the quadratic dependence of the refractive index on temperature. The method is straightforward and broadly applicable to other semiconductor systems, offering a valuable tool for the design of microphotonic devices, such as quantum light sources.

Ion transport at electrified interfaces is conventionally described by the redistribution of mobile ions to preserve local electroneutrality. Under extreme electrolyte confinement, however, this assumption fails as the characteristic transport length approaches the Debye screening length, giving rise to space-charge accumulation and slow electrostatic relaxation that dominate interfacial kinetics. Here, we introduce a fixed-charge-selective interphase in which immobile anionic charges replace mobile electrolyte anions as the primary charge-compensating species, thereby establishing a chemically encoded electrostatic boundary condition. Using a glucose-derived network as a model system, we show that localized fixed charge enables cation-selective transport and suppresses extended space-charge layers (ESCLs) by eliminating the slow relaxation pathways. Spatiotemporal transport analysis reveals that this interphase collapses multi-timescale interfacial relaxation into a unified kinetic regime. When applied to nanoliter-confined electrochemical systems (45 nL), rest-induced Coulombic efficiency (CE) collapse is reduced from 40% to 5%, demonstrating stabilization of electrostatic relaxation during idle periods, which is a failure mode intrinsic to microscale devices operating under duty cycles. The concept is further validated under pH-coupled and oxidative-stress conditions, sustaining stable operation with strong rate capability. These results define a general chemical strategy for regulating interfacial ion transport under confinement by replacing mobile charge compensation with molecularly fixed charges.

Thin-film self-assembly of three-dimensional (3D) microsystems presents a compelling route to integrate complex functionalities into ultra-compact volumes; yet, strategies for incorporating tunable ion-conducting elements remain limited. Here, we introduce a strain-induced self-assembly platform that transforms lithographically patterned multilayer thin films into functional 3D coaxial Swiss-roll microtubes with total active volumes below 1 µL. A key innovation is the monolithic integration of a chemically tunable polyimide proton exchange membrane, enabling post-fabrication optimization of ionic transport that balances proton transport with mediator blocking. We further implement a dual-mode operational scheme that decouples microbial metabolism from electrochemical power generation, revealing biofouling, not chemical fouling or membrane degradation, as the dominant failure mechanism in conventional architectures. Critically, optimally treated polyimide membranes exhibit excellent recoverability after fouling, while cell-free mode operation maintains stable performance by physically excluding microorganisms from the microelectronic environment. This integrated bio-electronic microsystem achieves a volumetric power density of 3.1 mW cm⁻3 within an ultra-compact footprint of 4.16 mm2. Our work establishes a scalable thin-film engineering approach to create tunable, 3D bioelectronic power sources for autonomous microsystems.

This study demonstrates the development of multifunctional printable piezoelectric actuators using PVDF-TrFE and PEDOT:PSS, capable of operating at low voltages and supporting a wide range of applications. By leveraging the high piezoelectric coefficient of PVDF-TrFE and the conductivity of PEDOT:PSS, the actuators exhibit stable performance with precise inkjet printing deposition and optimized waveform parameters. The fabrication process integrates inkjet printing and standard lithography, enabling monolithic integration for high-performance actuation and multifunctional sensing. The PVDF-TrFE-based actuators achieve low-voltage operation (as low as 50 V), efficient energy transfer, and mechanical stability. Enhancing the beta phase of PVDF-TrFE resulted in a deflection of approximate to 600 mu m and vortex generation, crucial for lift in aerial robotic applications. Durability tests confirmed minimal performance degradation after 2,300 actuation cycles. Beyond mechanical deflection, the actuators exhibit sound detection and strain sensing capabilities. Experimental evaluations validated their ability to differentiate sound frequencies, detect muscle strain, and replicate bio-inspired flight dynamics. A preliminary proof of concept for a double-wing structure demonstrated lift generation at low voltages and resonant frequencies. The results indicate that these piezoelectric actuators are well-suited for miniaturized robotic applications, particularly in aerial locomotion and multifunctional sensing, opening new possibilities for innovations in micro-robotics, wearables, and aerial robotics.

Manipulating the ionic-electronic coupling in organic electrochemical transistors (OECTs) offers opportunities for interesting phenomena and advanced applications but has not been systematically exploited. Here, we develop monolithically integrated solid-state vertical OECTs to fully explore polyelectrolyte's strengths, enabling the OECTs to switch between neuromorphic and logic functions. This transition capability is achieved by mastering the complex transport of large-size polycations within the channel through well-designed drain electrodes. Frame drains positioned atop the organic channel act as ion barriers, regulating the penetration and relaxation of polycations. This regulation allows our multilevel synaptic OECTs to transform from short-term depression (STD) to STD-based long-term memory, and eventually to long-term depression (LTD). Conversely, placing frame drains beneath the channel exposes the polyelectrolyte fully, hence yielding high-density logic OECTs, which have been successfully used to construct unipolar integrated circuits such as NOT, NAND, and NOR gates. These achievements represent a substantial advancement in manipulating polyelectrolyte-based ionic-electronic interactions, introducing more possibilities beyond small ion-based OECTs.

Shaping piezoelectrics into innovative 3D microstructures is an emerging field, offering the potential to unlock new functionalities through topological engineering. Existing methods can create 3D piezoelectric composites and origami‐inspired structures, but they often reduce electromechanical resonance quality, especially when using organic elastic backbones with low mechanical quality factors. At the same time, 2D free‐standing piezoelectric nanomembranes used in acoustic wave resonators require thin film materials with low intrinsic stress to prevent device rupture as lateral dimensions increase. In this work, the first example of 3D self‐assembled piezoelectrics composed entirely of inorganic materials is presented. By precisely controlling mechanical stress and the nanomembrane release process, free‐standing nanomembranes are shaped into conformably stable tubular structures. The resulting rolled‐up piezoelectric (RUP) structures can be tuned in diameter, length, and winding number to optimize their performance for either actuation or sensing applications. Tubes up to 11 mm in length and 3.5 mm in rolling length are demonstrated, with functionality confirmed through 1‐port interdigital transducers (IDT) and 2‐port delay‐line architectures, integrating up to 10 mm 2 of a free‐standing nanomembrane. Such devices can open new application possibilities for miniaturized medical devices, telecommunication, microfluidics, and energy harvesting, considering the large functional surface which adds another degree of freedom for topological design.

We demonstrate a scalable method for fabricating bright GaAs quantum dot (QD) photon sources by embedding them into broadband monolithic AlGaAs microlens arrays on gold-coated GaAs substrates. Cylindrical photoresist templates (2-5 µm diameter) are thermally reflowed and transferred into AlGaAs thin films using an optimized 3D reactive ion etching process. This yields large-area (2 mm × 4 mm), high-density (∼40×103 mm-2) microlens arrays of uniform shape. The brightest QD emissions are found in lenses with 2.7 µm diameter and 1.35 µm height. Finite-difference time-domain simulations of lens geometries reveal optimization potentials, including anti-reflection coatings. It is found that free-space and fiber-coupled extraction efficiencies can reach up to 62% and 37%, respectively. A statistical fabrication model, validated through photoluminescence spectroscopy, shows intensity enhancements up to × 200 in ca. 1 out of 200 lenses, aligning well with theoretical predictions. This approach highlights the promise of compact, efficient photon sources for future large-scale quantum network applications.

Spin light detection is a rapidly advancing field with significant impact on diverse applications in biology, medicine, and photonics. Developing integrated circularly polarized light (CPL) detectors is pivotal for next-generation compact polarimeters. However, previous compact CPL detectors, based on natural materials or artificial resonant nanostructures, exhibit intrinsically weak CPL polarization sensitivity, are susceptible to other polarization states, and suffer from limited bandwidths. A gradient-metasurface-contact CPL photodetector is demonstrated operating at zero-bias with a high discrimination ratio (approximate to 1.6 x 104), broadband response (500-1100 nm), and immunity to non-CPL field components. The photodetector integrates InSe flakes with CPL-selective metasurface contacts, forming an asymmetric junction interface driven by CPL-dependent unidirectional propagating surface plasmon waves, generating zero-bias vectorial photocurrents. Furthermore, it is implemented the developed CPL photodetector in a multivalued logic system and demonstrated the optical decoding of CPL-encrypted communication signals. This metasurface contact engineering represents a new paradigm in light property detection, paving the way for future integrated optoelectronic systems for on-chip polarization detection.

The vision of wearable microsystems that can continuously monitor physio-logical and biochemical signals has long inspired the healthcare electronics com-munity[1].Such devices could trans-form health management by enabling real-time diagnostics and personalized rehabilitation.However,their practi-cal deployment remains constrained by a simple but profound problem:how to build systems that are energy-autonomous and seamlessly integrated.The bottleneck is not a lack of functional components but the challenge of inte-grating energy storage,power delivery and sensing modules without com-promising compatibility,robustness or manufacturability.

Electrochemistry of heterostructures plays a fundamental role in developing high-performance energy storage and conversion devices. However, current superlattice heterostructures based on assembling 2D materials are limited to a small number of alternating units with weak interfacial interaction and ambiguous function mechanism. Herein, the high-order -Sn/TiO2/Sn/TiO2- (S/TO) superlattice heterojunctions with built-in electric fields (BIEFs) are designed for sodium storage using a strain release method. The results show that the accommodated BIEFs and the spatial confinement effect in this periodic nanostructured electrode co-contribute to the outstanding electrochemical performance. The nanosizing and pulverization of Sn are effectively space-limited in between the TiO2 slabs and the notorious catalytic reaction between electrolyte and TiO2 surface region is sophisticatedly mitigated by the electron accumulation in the TiO2 component, synergistically accelerating sodium storage and transfer kinetics of S/TO superlattice electrodes. The covalent Sn-O-Ti interactions further enhance the robustness to sustain repeated (de)sodiation processes. These findings provide a rewarding avenue towards the development of high-performance electrodes by heterostructural electrochemistry.

TheoreticalBerry phase and experimental results are presented, which introduce topology into the field of optical and plasmonic resonances in ring resonators. Due to occurrence of the Berry phase in non-trivial evolution, plasmon/photon modes with non-integer numbers of wavelengths along the circumference are revealed in metallic/dielectric Möbius ringsMöbius ring , which do not exist in conventional ring resonators. In cone-shaped anisotropic microtube resonatorAnisotropic microtube resonator s, the optical spin-orbit coupling is enabled for generation of the Berry phase acquired in a non-cyclic and non-Abelian evolution. These topology-induced effects imply promising applications related to manipulating photons in on-chip integrable quantum devices.

Precise and scalable enrichment of dispersed analytes is vital for biosensing, environmental monitoring, and nanomaterial processing. However, current methods often lack versatility and spatial resolution. Here, we introduce optothermal ice-water interface management (OIIM), a universal, label-free approach for cross-scale enrichment and sensing. By optically guiding a movable ice-water interface, OIIM creates a tunable and controllable nanovessel that actively drives analytes, from angstrom-scale dyes to micrometer-scale particles, into confined regions. This versatile approach efficiently enriches diverse targets, including nucleotides, proteins, and synthetic nanomaterials. Molecular dynamics simulations and fluorescence imaging have been investigated to elucidate the solute-interface interactions and the enhanced interfacial trapping underlie the observed enrichment behavior. Furthermore, OIIM supports multisite enrichment, spatial consolidation, and the formation of femtoliter-scale microreactors for accelerated enzyme-cascade reactions. Notably, OIIM offers unique capabilities for enriching and analyzing ultrashort nucleic acids that elude conventional purification methods, establishing a flexible, molecular-level optothermal strategy within ice.

Precisely capturing and manipulating microscale objects, such as individual cells and microorganisms, is fundamental to advancements in biomedical research and microrobotics. Photoactuators based on optical fibers serving as flexible, unobstructed waveguides are well-suited for these operations, particularly in confined locations where free-space illumination is impractical. However, integrating optical fibers with microscale actuators poses significant challenges due to size mismatch, resulting in slow responses inadequate for handling motile micro-objects. This study designs microactuators based on hydrogel/Au bilayer heterostructures that self-roll around a tapered optical fiber. This self-rolling mechanism enables the use of thin hydrogel layers only a few micrometers thick, which rapidly absorb and release water molecules during a phase transition. The resulting microactuators exhibit low bending stiffness and extremely fast responses, achieving large bending angles exceeding 800° within 0.55 s. Using this technique, this study successfully captures rapidly swimming Chlamydomonas and Paramecium, and demonstrates programmable non-reciprocal motion for effective non-contact manipulation of yeast cells. This approach provides a versatile platform for microscale manipulations and holds promise for advanced biomedical applications.

Single plasmonic nanoparticles coupled to a whispering-gallery-mode (WGM) microcavity provide an excellent platform to explore enhanced light-matter interactions. Here, we demonstrate switchable coupling between localized surface plasmon resonances (LSPRs) and three-dimensionally (3D) confined WGMs in an optoplasmonic system composed of a single gold nanorod and a microtubular cavity. The photon-plasmon coupling is efficiently switched between an "ON" and "OFF" state by tuning the excitation of the LSPR to match or mismatch the WGMs, where spectral match and spatial overlap play crucial roles. This switching phenomenon is indicated by the observations of spectral energy shifts, intensity variations, and spatial redistributions of the 3D confined WGMs. To explain the observed results, a deformed potential well model is introduced based on perturbation theory, where the polarizability and enhanced electric field induced by the single plasmonic nanorod are considered. The present work provides a convenient way to manipulate the photon-plasmon coupling in a hybrid optoplasmonic system, paving the way for controllable light-matter interactions and opening up promising applications in future subwavelength photonic technologies.

Spin light detection is a rapidly advancing field with significant impact on diverse applications in biology, medicine, and photonics. Developing integrated circularly polarized light (CPL) detectors is pivotal for next-generation compact polarimeters. However, previous compact CPL detectors, based on natural materials or artificial resonant nanostructures, exhibit intrinsically weak CPL polarization sensitivity, are susceptible to other polarization states, and suffer from limited bandwidths. A gradient-metasurface-contact CPL photodetector is demonstrated operating at zero-bias with a high discrimination ratio (≈1.6 ✗ 10 4 ), broadband response (500–1100 nm), and immunity to non-CPL field components. The photodetector integrates InSe flakes with CPL-selective metasurface contacts, forming an asymmetric junction interface driven by CPL-dependent unidirectional propagating surface plasmon waves, generating zero-bias vectorial photocurrents. Furthermore, it is implemented the developed CPL photodetector in a multivalued logic system and demonstrated the optical decoding of CPL-encrypted communication signals. This metasurface contact engineering represents a new paradigm in light property detection, paving the way for future integrated optoelectronic systems for on-chip polarization detection.