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Abstract The dielectric gap between the scanning probe microscopy (SPM) tip and the surface of a ferroelectric using conductive atomic force microscopy and piezoresponse force microscopy (PFM) is investigated. While the gap functions as a dielectric layer, it also allows tunneling current to inject charges into the ferroelectric when a critical loading force between 10–20 µN is applied to a tip with a radius of 25 nm under a bias voltage of 0.5 V. It is observed that the permittivity of the dielectric gap determines the coercive voltage measured by the piezoresponse hysteresis loop. While such studies done in air often produce coercive voltages much larger than those studied for the same materials in capacitor‐based studies, the use of high permittivity media such as water (ɛ_r= 79) or silicone oil (ɛ_r= 2.1‐2.8) produces coercive fields that more closely match those measured in conventional capacitor‐based polarization hysteresis loop measurements. Furthermore, using water as a dielectric medium in PFM imaging enhances the accuracy in extracting the amplitude and phase data from periodically poled lithium niobate crystals. These findings provide insight into the nanoscale phenomena of polarization switching instigated by the SPM tip and provide a pathway to improved quantitative studies. 

Abstract Recent advancements in wearable photonic sensors have marked a transformative era in healthcare, enabling non‐invasive, real‐time, portable, and personalized medical monitoring. These sensors leverage the unique properties of light toward high‐performance sensing in form factors optimized for real‐world use. Their ability to offer solutions to a broad spectrum of medical challenges – from routine health monitoring to managing chronic conditions, inspires a rapidly growing translational market. This review explores the design and development of wearable photonic sensors toward various healthcare applications. The photonic sensing strategies that power these technologies are first presented, alongside a discussion of the factors that define optimal use‐cases for each approach. The means by which these mechanisms are integrated into wearable formats are then discussed, with considerations toward material selection for comfort and functionality, component fabrication, and power management. Recent developments in the space are detailed, accounting for both physical and chemical stimuli detection through various non‐invasive biofluids. Finally, a comprehensive situational overview identifies critical challenges toward translation, alongside promising solutions. Associated future outlooks detail emerging trends and mechanisms that stand to enable the integration of these technologies into mainstream healthcare practice, toward advancing personalized medicine and improving patient outcomes. 

Abstract Chalcogenide optical phase change materials (PCMs) have garnered significant interest for their growing applications in programmable photonics, optical analog computing, active metasurfaces, and beyond. Limited endurance or cycling lifetime is however increasingly becoming a bottleneck toward their practical deployment for these applications. To address this issue, a systematic study elucidating the cycling failure mechanisms of Ge₂Sb₂Se₄Te (GSST) is performed, a common optical PCM tailored for infrared photonic applications, in an electrothermal switching configuration commensurate with their applications in on‐chip photonic devices. Further a set of design rules building on insights into the failure mechanisms is proposed, and successfully implemented them to boost the endurance of the Ge₂Sb₂Se₄Te (GSST) device to over 67 000 cycles. 

Abstract We introduce the heterocumulene ligand [(Ad)NCC(^tBu)]⁻(Ad=1‐adamantyl (C₁₀H₁₅),^tBu=tert‐butyl, (C₄H₉)), which can adopt two forms, the azaalleneyl and ynamide. This ligand platform can undergo a reversible chelotropic shift using Brønsted acid‐base chemistry, which promotes an unprecedented spin‐state change of the [V^III] ion. These unique scaffolds are prepared via addition of 1‐adamantyl isonitrile (C≡NAd) across the alkylidyne in complexes [(BDI)V≡C^tBu(OTf)] (A) (BDI⁻=ArNC(CH₃)CHC(CH₃)NAr), Ar=2,6‐ⁱPr₂C₆H₃) and [(dBDI)V≡C^tBu(OEt₂)] (B) (dBDI²⁻=ArNC(CH₃)CHC(CH₂)NAr). ComplexAreacts with C≡NAd, to generate the high‐spin [V^III] complex with a κ¹‐N‐ynamide ligand, [(BDI)V{κ¹‐N‐(Ad)NCC(^tBu)}(OTf)] (1). Conversely,Breacts with C≡NAd to generate a low‐spin [V^III] diamagnetic complex having a chelated κ²‐C,N‐azaalleneyl ligand, [(dBDI)V{κ²‐N,C‐(Ad)NCC(^tBu)}] (2). Theoretical studies have been applied to better understand the mechanism of formation of2and the electronic reconfiguration upon structural rearrangement by the alteration of ligand denticity between1and2. 

Abstract Electrochemical nitrate reduction reaction (NO₃RR) has garnered increasing attention as a pathway for converting a harmful pollutant (nitrate) into a value‐added product (ammonia). However, high selectivity toward ammonia (NH₃) is imperative for process viability. Optimizing proton availability near the catalyst is important for achieving selective NH₃production. Here, the aim is to systematically examine the impacts of proton availability on NO₃RR selectivity in a bipolar membrane (BPM)‐based membrane electrode assembly (MEA) system. The BPM generates a proton flux from the membrane toward the catalyst during electrolysis. Thus, the BPM‐MEA system can modulate the proton flux during operation. The impact of interposer layers, proton scavenging electrolytes (CO₃²⁻), and catalyst configurations are also examined to identify which local microenvironments favor ammonia formation. It is found that a moderate proton supply allows for an increase in ammonia yield by 576% when compared to the standard MEA setup. This also results in a high selectivity of 26 (NH₃over NO₂⁻) at an applied current density of 200 mA cm⁻². 

Abstract Topological solitons have knotted continuous field configurations embedded in a uniform background, and occur in cosmology, biology, and electromagnetism. However, real‐time observation of their morphogenesis and dynamics is still challenging because their size and timescale are enormously large or tiny. Liquid crystal (LC) structures are promising candidates for a model‐system to study the morphogenesis of topological solitons, enabling direct visualization due to the proper size and timescale. Here, a new way is found to rationalize the real‐time observation of the generation and transformation of topological solitons using cholesteric LCs confined in patterned substrates. The experimental demonstration shows the topologically protected structures arise via the transformation of topological defects. Numerical modeling based on minimization of free energy closely reconstructs the experimental findings. The fundamental insights obtained from the direct observations pose new theoretical challenges in understanding the morphogenesis of different types of topological solitons within a broad range of scales.