The development of adaptive material platforms that integrate proton radiation shielding with energy storage capabilities is critical for achieving both miniaturization and cost-effective reliability in space electronics. Here, we present an industrially viable technology for fabricating covalent amorphous alumina-hydrogenated graphene (AHG) films that can attenuate energetic protons, store electrical energy, and adapt to downsizing. Specifically, the fabrication involves thermal-driven precipitation and crystallization of carbon species into hydrogenated graphene layers, along with oxidation of aluminum into amorphous alumina, on a nickel-copper alloy surface. AHG films exhibit effective attenuation of energetic protons (15.2 MeV, 4.3 × 1012 p/cm2), primarily attributed to proton trapping via C─H bond formation within the film matrix. Moreover, AHG films are laser-scribed into interdigitated electrodes for constructing micro-supercapacitors (µ-SCs) with impressive energy (8.33 mWh/cm3) and power (130 mW/cm3) densities. Operando measurements of the AHG µ-SCs demonstrate their dual functions in reducing the incident protons by ∼1.9 MeV in energy and ∼5.8 × 1011 protons/cm2 in fluence, while maintaining stable capacitive behavior with ∼93% capacitance retained after the severe irradiation. These findings suggest significant potential for developing single multifunctional products as a replacement for both traditional radiation shields and energy storage devices in next-generation space electronics.

Photon avalanche upconversion nanoparticles exhibit extremely high nonlinear responses and threshold-dependent upconversion luminescence, while cyclic olefin copolymer resonant waveguide grating structures transduce small ambient refractive index changes into guided-mode resonance wavelength shifts. By coupling these two elements, we developed a hybrid nanophotonic platform with exceptional environmental sensitivity. Tm3+-doped NaYF4 photon avalanche upconversion nanoparticles were deposited onto a water-covered cyclic olefin copolymer resonant waveguide grating designed to support a guided-mode resonance at 1064 nm, matching the excitation laser wavelength and generating strong local excitation fields that enhance the photon avalanche process and yield intense upconversion luminescence. Small variations in the environmental refractive index shifted the guided-mode resonance wavelength away from the excitation wavelength, markedly reducing the local excitation power density and dramatically altering the photon avalanche upconversion luminescence characteristics. At an excitation power density of 1.18 kW/cm2, increasing the environmental refractive index (n) from 1.33250 to 1.37233 caused an exponential decrease in upconversion luminescence intensity, yielding a remarkably high local relative sensitivity of 9477%/RIU at n = 1.33250. In contrast, under the same environmental refractive index variation range but at a higher excitation power density of 7.5 kW/cm2, photon avalanche upconversion nanoparticles on a water-covered glass substrate showed only minor luminescent intensity changes, corresponding to a substantially lower average relative sensitivity of 737 %/RIU. These findings demonstrate that coupling photon avalanche upconversion nanoparticles to a resonant waveguide grating structure enables ultrahigh ambient refractive-index sensitivity and highlights the strong potential of this hybrid nanophotonic platform for next-generation ultrasensitive biosensing applications.

With the increasing use of Commercial Off-the-Shelf (COTS) components in low-earth orbit (LEO) satellites, their vulnerability to the high-energy proton radiation has become a critical reliability concern, requiring effective yet lightweight shielding. Conventional shielding methods, including heavy metal coatings, hydrogen-rich polymers, and carbon-based materials, often suffer from drawbacks such as high mass, large thickness, or complex implementation. Recently, a lightweight hybrid shielding material composed of hydrogenated graphene and amorphous alumina, integrated with polyethylene terephthalate (AHG/PET), demonstrated a similar to 64.2% reduction in incident proton charge, with a total thickness of similar to 0.876 mm and an estimated mass of only 0.314 g. While Monte Carlo simulations using SRIM/TRIM and Geant4 can successfully describe proton transport and energy attenuation, the experimentally observed increase in C-H bonding after irradiation cannot be explained by Geant4 alone, indicating the presence of additional interaction mechanisms for the shielding effectiveness. In this work, first-principles density functional theory (DFT) combined with Monte Carlo simulations is used to investigate the mechanism of enhanced shielding and charge storage behavior. The results show that multilayer structures increase collision probability, enabling secondary protons to reach lower energies, where protonassisted bonding in hydrogenated graphene becomes favorable, explaining the improved shielding performance consistent with experiments.

We propose and demonstrate one-dimensional (1-D) TiO2 dielectric grating structures that couple 793-nm wavelength light and two-dimensional (2-D) surface plasmon polaritons (SPPs) into guided 1-D SPPs supported by dielectric-loaded plasmonic waveguides. The 1-D grating structure consists of a central TiO2 stripe with a periodic array of TiO2 teeth attached to the stripe. Finite-difference time-domain (FDTD) simulations reveal that the electromagnetic boundary conditions created by the teeth bend the electric field and induce charge oscillations under the grating, enabling excitation of SPPs. The same mechanism supports the routing of 2-D SPP. In the simulation the symmetric gratings achieve a maximum coupling efficiency of 19.1 % at an optimized grating period of Λ = 600 nm, and 1.7 % for asymmetric gratings. Both types exhibit strong polarization selectivity: symmetric gratings couple only under TM excitation, whereas asymmetric gratings respond under TE excitation. Experimental confirms these behaviors, yielding a coupling efficiency of ∼13 % for optimized symmetric gratings. The structures also function as SPP routers. Asymmetric gratings route incoming 2-D SPPs into 1-D TiO2 waveguides with a simulated routing efficiency of 5.7 %, compared to 4.0 % for symmetric designs. The devices offer a ∼14 nm bandwidth around 793 nm and a small footprint of 18.7 μm2, resulting in a figure of merit (efficiency/area) of 0.71 % μm−2, the highest among reported devices designed to couple free-space light directly into 1-D SPP waveguides. These results demonstrate that 1-D TiO2 gratings offer a compact and multifunctional platform for efficient coupling and routing of SPPs in integrated plasmonic circuits.

Photon avalanche (PA) upconverting nanoparticles (UCNPs) have attracted great interest because they can exhibit giant changes in upconversion luminescence (UCL) intensity through small perturbations of excitation light. The discovery of PA UCNPs opens up their applications in super-resolution imaging, microlasers and optical and environmental sensing. These applications rely heavily on low PA threshold and high nonlinear order PA UCNPs. So far, the PA threshold of PA UCNPs can only be reduced through material modification. In this work, a strategy is proposed to reduce the required excitation intensity of the excitation light source to generate PA UCL from PA UCNPs through the guided-mode resonance (GMR) effect of an optimal resonant waveguide grating (RWG) structure. Before using the RWG structure, Tm3+-doped NaYF4 (NaYF4:Tm3+) core PA UCNPs deposited on a glass substrate required an excitation intensity of similar to 7.1 kW/cm2 from the excitation light source to produce PA UCL and with a nonlinear order (n) similar to 25.9. In comparison, when core PA UCNPs were coated on the surface of the water-covered RWG structure and excited under the GMR condition, only an excitation intensity 2.72 kW/cm2 from the excitation light source was needed to induce PA UCL with nonlinear order of n similar to 39.5. This is because a strongly enhanced local electric field is formed on the surface of the RWG structure, which enhances the interaction between the excitation light and core PA UCNPs, thereby significantly reducing the excitation intensity of the excitation light source required to generate PA UCL from core PA UCNPs. The RWG structure can powerfully enhance the PA UCL performance of PA UCNPs. The combination of the RWG structure and PA UCNPs can be developed into ultrasensitive sandwich-type immunosensors for biosensing applications.

Selective detection of biomarkers at low concentrations in blood is crucial for the clinical diagnosis of many diseases but remains challenging. In this work, we aimed to develop an ultrasensitive immunoassay that can detect biomarkers in serum with an attomolar limit of detection (LOD). We proposed a sandwich-type heterogeneous immunosensor in a 3 × 3 well array format by integrating a resonant waveguide grating (RWG) substrate with upconversion nanoparticles (UCNPs). UCNPs were used to label a target biomarker captured by capture antibody molecules immobilized on the surface of the RWG substrate, and the RWG substrate was used to enhance the upconversion luminescence (UCL) of UCNPs through excitation resonance. The LOD of the immunosensor was greatly reduced due to the increased UCL of UCNPs and the reduction of nonspecific adsorption of detection antibody-conjugated UCNPs on the RWG substrate surface by coating the RWG substrate surface with a carboxymethyl dextran layer. The immunosensor exhibited an extremely low LOD [0.24 fg/mL (9.1 aM)] and wide detection range (1 fg/mL to 100 pg/mL) in the detection of cardiac troponin I (cTnI). The cTnI concentrations in human serum samples collected at different times during cyclophosphamide, epirubicin, and 5-fluorouracil (CEF) chemotherapy in a breast cancer patient were measured by an immunosensor, and the results showed that the CEF chemotherapy did cause cardiotoxicity in the patient. Having a higher number of wells in such an array-based biosensor, the sensor can be developed as a high-throughput diagnostic tool for clinically important biomarkers.

We propose and demonstrate dielectric Fresnel phase zone pad (FPZP) structures for focusing surface plasmon polaritons (SPPs) propagating at the SiO2/Ag interfaces. We exploited up-conversion fluorescence microscopy to characterize the SPP focusing. We first report on the SPP focusing with 2-level FPZP structures that introduced a π-phase shift in the SPP wavefront between adjacent zones. We optimized the SPP focusing by fine-tuning the longitudinal width of the FPZP structure. This led to the enhancement of the peak intensity of the SPP focal spot and the reduction of the focal spot size in both the longitudinal and transverse directions. Such focusing was also demonstrated with different focal lengths. To further improve the SPP focusing, we developed a 4-level FPZP structure, which introduced a π/2-phase shift in the SPP wavefront between adjacent zones. With the optimized 4-level FPZP structure, the SPP focal spot peak intensity is further improved, and the spot size is reduced. To assist the design of the FPZP structures, we carried out theoretical analysis and numerical calculations to determine the SPP wavelengths at various oxide/Ag interfaces. We also carried out finite difference time domain (FDTD) calculations to simulate the SPP focusing with the FPZP structures. The results of the FDTD simulation agree with the experimental results qualitatively.

The outstanding properties of graphene, including its electromechanical property, could be engineered for wearable electronic sensor platforms. The tubular graphene weaved into a mesh or graphene woven fabrics (GWF) has been reported as one of the most sensitive materials for deformation detection, as well as a promising temperature sensor. Herein, we present the performance of our developed flexible, stretchable, and multiple sensitive sensors fabricated from GWF embedded in polydimethylsiloxane (PDMS) film substrate. The GWF/PDMS sensor shows a pressure sensitivity of 0.0142 kPa-1 in a wide linearity range of 0-20 kPa, an outstanding Gauge factor (GF) of 582 at a strain of 6.2 %, and a very high positive sensitivity of 0.0238 °C-1 in the temperature range of 25-80 °C. A practical application as a high sensitivity air pressure sensor able to measure low pressures (in the range of Pa to kPa) was also demonstrated. This sensor platform having desirable performance characteristics is an excellent candidate for wearable devices in the healthcare sector.

Imaging and characterization of surface plasmon polaritons (SPPs) are crucial for the research and development of the plasmonic devices and circuits. Here, we report on direct imaging of SPPs propagation on SiO2/metal interface with subwavelength spatial resolution using up-conversion fluorescence microscopy, that exploits rare-earth ions, such as Er3+, Yb3+, and Nd3+, doped nanoparticles as the fluorophores. We demonstrated that by further taking the intensity ratio of the image obtained with fluorescent emission at different wavelengths, we are able to substantially enhance the features associated to the SPP wavefronts in the image for quantitative analysis, such as the wavevector and propagation direction of the SPPs. Our results agree with the theoretic prediction of the SPP wavelengths quantitatively. We further demonstrate the evolution of the SPP wavefronts due to refraction SPPs, and reproduced the experiment with finite difference time domain (FDTD) method simulations. The relative refractive index of SPP estimated from the experiment also agrees quantitatively with those extracted from the theory and the simulation.

Pt-based alloy or bimetallic anode catalysts have been developed to reduce the carbon monoxide (CO) poisoning effect and the usage of Pt in direct methanol fuel cells (DMFCs), where the second metal plays a role as CO poisoning inhibitor on Pt. Furthermore, better performance in DMFCs can be achieved by improving the catalytic dispersion and using high-performance supporting materials. In this work, we introduced a free-standing, macroscopic, interwoven tubular graphene (TG) mesh as a supporting material because of its high surface area, favorable chemical inertness, and excellent conductivity. Particularly, binary AuPt nanoparticles (NPs) can be easily immobilized on both outer and inner walls of the TG mesh with a highly dispersive distribution by a simple and efficient chemical reduction method. The TG mesh, whose outer and inner walls were decorated with optimized loading of binary AuPt NPs, exhibited a remarkably catalytic performance in DMFCs. Its methanol oxidation reaction (MOR) activity was 10.09 and 2.20 times higher than those of the TG electrodes with only outer wall immobilized with pure Pt NPs and binary AuPt NPs, respectively. Furthermore, the catalyst also displayed a great stability in methanol oxidation after 200 scanning cycles, implying the excellent tolerance toward the CO poisoning effect.

Erbium ion (Er3+)-doped upconversion nanoparticles (UCNPs) are frequently used for nanothermometry because their fluorescence intensity ratio (FIR) between two green emission bands at -,525 and -,545 nm is sensitive to temperature variation. One of the prerequisites for nanothermometry is that the FIR be independent of excitation intensity at constant temperature. In this work, the effect of excitation intensity on the FIR of core-double-shell NaYF4:Yb3+,Er3+@NaYF4:Yb3+,Nd3+@NaYF4 UCNPs was investigated in two environments. The first environment is in aqueous solution, and the second is a monolayer of UCNPs on top of a silica-silicon substrate in air. The experimental results showed that the FIR decreases with the excitation intensity at constant temperature in each case. We further found that the excitation intensity-dependent FIR indeed deteriorated the thermal images acquired by wide-field upconversion fluorescence microscopy, in which a Gaussian laser beam was used to excite UCNPs uniformly coated on a silica-silicon substrate. The nonuniform excitation intensity of the incident laser beam resulted in thermal images that showed nonuniform temperature distributions in a 100 mu m range field of view, even though the whole sample was maintained at constant temperature in air. To tackle this problem, we first measured the excitation intensity and temperature dependence of the FIR and the excitation laser intensity distribution on the sample. We then developed a correction scheme to correct the thermal images. With our correction process, the temperature distribution on the sample can be accurately mapped even with nonuniform illumination.

Lanthanide (Ln3+)–doped upconversion nanoparticles (UCNPs) offer an ennormous future for a broad range of biological applications over the conventional downconversion fluorescent probes such as organic dyes or quantum dots. Unfortunately, the efficiency of the anti−Stokes upconversion luminescence (UCL) process is typically much weaker than that of the Stokes downconversion emission. Albeit recent development in the synthesis of UCNPs, it is still a major challenge to produce a high−efficiency UCL, meeting the urgent need for practical applications of enhanced markers in biology. The poor quantum yield efficiency of UCL of UCNPs is mainly due to the fol-lowing reasons: (i) the low absorption coefficient of Ln3+ dopants, the specific Ln3+ used here being ytterbium (Yb3+), (ii) UCL quenching by high−energy oscillators due to surface defects, impurities, ligands, and solvent molecules, and (iii) the insufficient local excitation intensity in broad-field il-lumination to generate a highly efficient UCL. In order to tackle the problem of low absorption cross-section of Ln3+ ions, we first incorporate a new type of neodymium (Nd3+) sensitizer into UCNPs to promote their absorption cross-section at 793 nm. To minimize the UCL quenching induced by surface defects and surface ligands, the Nd3+-sensitized UCNPs are then coated with an inactive shell of NaYF4. Finally, the excitation light intensity in the vicinity of UCNPs can be greatly enhanced using a waveguide grating structure thanks to the guided mode resonance. Through the synergy of these three approaches, we show that the UCL intensity of UCNPs can be boosted by a million−fold compared with conventional Yb3+–doped UCNPs.

We present here a simple and robust photolithography method to fabricate high-porosity SU-8 negative resist templates using positive Poly(methyl methacrylate) (PMMA) as the porogenic agent. We report on how these nanoporous structures are greatly affected by the volume fraction of each component in the precursor solution and by the amount of exposure, to be limited to grant sufficient access to PMMA chains during pore formation. Tuning the porosity of the SU-8 film, we could broadly tailor its effective refractive index (n) from n = 1.27 to 1.58, in the visible/near-infrared domain. By further using the interference lithography technique, we demonstrated various kinds of porous micro/nanostructured surfaces. A hydrophobic effect was demonstrated with a high water contact angle of 130°. Such porous SU-8 templates could enhance, at modest cost, the design room of polymer-based photonic architectures in many areas, such as sensing, microfluidic and optoelectronic device.

The major challenge in photothermal therapy (PTT) is to develop nanocomposites that simultaneously exhibit bioimaging and PTT under a single near-infrared (NIR) irradiation with high therapeutic efficiency. Herein, we present a multifunctional nanocomposite synthesized by linking NaYF4:Yb3+,Er3+ upconversion nanoparticles (UCNPs) with gold nanorods (AuNR) to exhibit fluorescence labeling, local temperature sensing and photothermal functions simultaneously with a single NIR laser excitation. The AuNR-NaYF4:Yb3+,Er3+ nanocomposite particles displayed better photothermal properties compared with pure AuNRs or a blend of AuNRs and NaYF4:Yb3+,Er3+ UCNPs. The temperature-dependent upconversion luminescence (UCL) property was used to determine local temperature at the nanocomposite particles, which is useful for selecting appropriate irradiation dosage for PTT. The therapeutic performance of the nanocomposites in PTT for OML-1 oral cancer cells was determined. For cell labeling, we successfully labeled streptavidin-linked nanocomposite particles on the surface of OML-1 oral cancer using anti-human epidermal growth factor receptor 2 (anti-Her2) antibody. Finally, the nanocomposite particles caused exceptional destruction of cancer cells up to 70% dead cells under 976 nm laser irradiation for only one min at 0.3 W/cm2 which is below the maximal permissible exposure of human skin.

We introduce a compact array fluorescence sensor principle that takes advantage of the long luminescence lifetimes of upconversion nanoparticles (UCNPs) to deploy a filter-free, optics-less contact geometry, advantageous for modern biochemical assays of biomolecules, pollutants or cells. Based on technologically mature CMOS chips for ∼10 kHz technical/scientific imaging, we propose a contact geometry between assayed molecules or cells and a CMOS chip that makes use of only a faceplate or direct contact, employing time-window management to reject the 975 nm excitation light of highly efficient UCNPs. The chip surface is intended to implement, in future devices, a resonant waveguide grating (RWG) to enhance excitation efficiency, aiming at the improvement of upconversion luminescence emission intensity of UCNP deposited atop of such an RWG structure. Based on mock-up experiments that assess the actual chip rejection performance, we bracket the photometric figures of merit of such a promising chip principle and predict a limit of detection around 10-100 nanoparticles.

The development of graphene structures with controlled edges is greatly desired for understanding heterogeneous electrochemical (EC) transfer and boosting EC applications of graphene-based electrodes. We herein report a facile, scalable, and robust method to produce graphene mesh (GM) electrodes with tailorable edge lengths. Specifically, the GMs were fabricated at 850 °C under a vacuum level of 0.6 Pa using catalytic nickel templates obtained based on a crack lithography. As the edge lengths of the GM electrodes increased from 5.48 to 24.04 m, their electron transfer rates linearly increased from 0.08 to 0.16 cm∙s−1, which are considerably greater than that (0.056 ± 0.007 cm∙s−1) of basal graphene structures (defined as zero edge length electrodes). To illustrate the EC sensing potentiality of the GM, a high-sensitivity glucose detection was conducted on the graphene/Ni hybrid mesh with the longest edge length. At a detection potential of 0.6 V, the edge-rich graphene/Ni hybrid mesh sensor exhibited a wide linear response range from 10.0 μM to 2.5 mM with a limit of detection of 1.8 μM and a high sensitivity of 1118.9 μA∙mM−1∙cm−2. Our findings suggest that edge-rich GMs can be valuable platforms in various graphene applications such as graphene-based EC sensors with controlled and improved performance.

In this work, we present efficient, robust, and transparent electromagnetic interference (EMI) shielding by a hybrid material comprised of a nickel (Ni) mesh and a conformal graphene coating. We demonstrate that a 20 nm-thick graphene/Ni hybrid mesh can provide EMI shielding effectiveness (SE) exceeding 12.1 dB (similar to 93.6% power attenuation) in the decimeter band while retaining a high visible transmittance of similar to 83%. Its maximum achieved SE value was 26.6 dB (similar to 99.5% power attenuation) at 0.75 GHz. Furthermore, the thicker Ni mesh exhibited a higher EMI SE. Compared to a conventional Ni mesh, the hybrid mesh exhibits a higher SE and a greatly improved corrosion resistance. The graphene coating is directly grown on a Ni mesh via rapid annealing of solid carbon precursors under low vacuum. Scalable fabrication of the mesh was achieved by a self-formed TiO2 crack network template. Our results not only provide a promising material for high-performance EMI shielding in optoelectronics devices but also enable applications of EMI shielding in harsh environments.

Barrier-guided CVD growth could provide a new route to printed electronics by combining high quality 2D materials synthesis with scalable and cost-effective deposition methods. Unfortunately, we observe the limited stability of the barrier at growth conditions which results in its removal within minutes due to hydrogen etching. This work describes a route towards enhancing the stability of an ink-jet deposited barrier for high resolution patterning of high quality graphene. By modifying the etching kinetics under confinement, the barrier film could be stabilized and high resolution barriers could be retained even after 6 hours of graphene growth. Thus produced microscopic graphene devices exhibited an increase in conductivity by 6 orders of magnitude and a decrease in defectiveness by 48 times yielding performances that are superior to devices produced by traditional lithographical patterning which indicates the potential of our approach for future electronic applications.

Lateral heterojunctions in two-dimensional (2D) materials have demonstrated potential for high-performance sensors because of the unique electrostatic conditions at the interface. The increased complexity of producing such structures, however, has prevented their widespread use. We here demonstrate the simple and scalable fabrication of heterojunctions by a one-step synthesis process that yields photodetectors with superior device performance. Catalytic conversion of a solid precursor at optimized conditions was found to produce lateral nanostructured junctions between graphene domains and 3 nm thin amorphous carbon films. Carrier transport in these heterojunctions was found to proceed by minimizing the path through the amorphous carbon barriers, which results in a self-selective Schottky emission process with high uniformity and low emission barriers. We demonstrate the potential of thus produced heterojunctions by realizing a photodetector that combines an ultrahigh detectivity of 1013 Jones with microsecond response time, which represents the highest performance of 2D material heterojunction devices. These attractive features are retained even for millimeter-scale devices, and the demonstrated ability to produce transparent, patterned, and flexible sensors extends lateral heterojunction sensors toward wearable and large-scale electronics.