Photonic cavity enhanced high-performance surface plasmon resonance biosensor

Herein we propose a novel strategy to enhance surface plasmon resonance(SPR)by introducing a photonic cavity into a total-internal-reflection architecture.The photonic cavity,which is comprised of a highly reflective photonic crystal(PC),defect layers,and a gold(Au)film,enables Fabry–Perot(FP)resonances in the defect layers and therefore narrows the SPR resonance width in the metallic surface as well as increases the electric field intensity and penetration depth in the evanescent region.The fabricated sensor exhibits a 5.7-fold increase in the figure of merit and a higher linear coefficient as compared with the conventional Au-SPR sensor.The demonstrated PC/FP cavity/metal structure presents a new design philosophy for SPR performance enhancement.

One-step plasmonic welding and photolithographic patterning of silver nanowire network by UV-programable surface atom diffusion

Silver nanowire(AgNW)based transparent electrode(TE)plays a pivotal role in optoelectronics where TE is generally required to have fine pattern and high performance.Despite the rapid technological advances in either welding or patterning of AgNWs,there are few studies that combine the two processes in a simple and practical manner.Here,aiming to fabricate high-performance patterned AgNW TE,we develop a simplified photolithography that enables both plasmonic nanowelding with low-level UV exposure(20 mW/cm^(2))and high-resolution micropatterning without photoresist and etching process by conjugating AgNW with diphenyliodonium nitrate(DPIN)and UV-curable cellulose.The cellulose as a binder can effectively enhance plasmonic heating,adhesion,and stability,while the photosensitive DPIN,capable of modulating surface atom diffusion,can boost the plasmonic welding at AgNW junction and induce patterning in AgNW network with Plateau-Rayleigh instability.The fabricated AgNW TE has high figure of merit of up to 1,000(3.7Ω/sq at 90%transmittance)and minimal pattern size down to 3µm,along with superior robustness.Finally,a flexible smart window with high performance is demonstrated using the patterned and welded AgNW TEs,verifying the applicability of the simplified photolithography technique to optoelectronic devices.

Self-assembled monolayer modulated Plateau-Rayleigh instability and enhanced chemical stability of silver nanowire for invisibly patterned,stable transparent electrodes

Patterned silver nanowire(AgNW)networks have been widely used as transparent electrodes in many optoelectrical devices.However,obvious patterning visibility and poor thermostability of AgNW are still limiting its practical application.Herein,we report self-assembled monolayer(SAM)modulated Plateau-Rayleigh instability(PRI)of AgNW,which allows invisible patterning and superior stability of the AgNW network.Two opposite effects of different SAMs on the PRI are identified:the alkanethiol SAMs activate surface atom diffusion while the mercaptobenzoheterocyclic(MBH)SAMs suppress the diffusion.The degradation temperature of the AgNWs can be therefore,for the first time,tuned in the range of 193-381℃,so that the AgNW network can be patterned via PRI with a tiny optical difference between the insulative and conductive regions,i.e.,patterning invisible.Besides,the MBH SAMs provide AgNW with excellent durability under thermal annealing and oxidation,which enhances the maximum heating temperature of the AgNW transparent heater by over 120℃.Beyond the micro-patterning,we consider that the developed SAM strategy can be extended to other metal nanowires for stability improvement and has huge potential in nanoengineering of one-dimensional metal materials.

Highly sensitive vector magnetic fiber sensor based on hyperbolic metamaterials

Hyperbolic metamaterials(HMMs) are novel artificial materials that excite the surface plasmon resonance(SPR) because of their unique hyperbolic dispersion properties. Herein, to the best of our knowledge, we propose the first HMM-based fiber SPR(HMM-SPR) sensor for vector magnetic detection. By selecting the composite materials and structural parameters of the HMM dispersion management, HMM-SPR sensors can achieve a high refractive index sensitivity of 14.43 μm/RIU. Vector magnetic field detection was performed with the HMM-SPR sensor encapsulated with a magnetic fluid. Compared with other ferrofluidbased magnetic field fiber sensors, the proposed sensor shows pronounced advantages in intensity and direction sensitivity of 1.307 nm/Oe and 7.116 nm/°, respectively. The sensor design approach presented in this paper provides an excellent demonstration of HMM-SPR sensors in various applications.