A Free-Standing Self-Assembled Tubular Conjugated Polymer Sensor

Tubular materials created by self-assembly of small organic molecules have gained great attention recently. Fabrication of tubular structures that have precise dimensions by using conventional self-assembly approaches is extremely challenging. Herein we describe fabrication of a free-standing tubular polydiacetylene (PDA) sensor based on the meniscus-guided self-assembly and polymerization of diacetylene (DA) monomers. The free-standing single PDA tube can be utilized as an unprecedented microcapillary-based sensor system, which requires only a minimum amount (70–140 nL) of an analyte solution. We have observed 4 orders of magnitude more sensitive to analytes than is a conventional PDA sensor when a biotin-functionalized PDA tube is exposed to streptavidin. The microcapillary-based analytical method developed in this study should find great utility not only for PDA sensors but also for other free-standing wire sensor systems

Proposition of Adaptive Read Bias: A Solution to Overcome Power and Scaling Limitations in Ferroelectric‐Based Neuromorphic System

Abstract Hardware neuromorphic systems are crucial for the energy‐efficient processing of massive amounts of data. Among various candidates, hafnium oxide ferroelectric tunnel junctions (FTJs) are highly promising for artificial synaptic devices. However, FTJs exhibit non‐ideal characteristics that introduce variations in synaptic weights, presenting a considerable challenge in achieving high‐performance neuromorphic systems. The primary objective of this study is to analyze the origin and impact of these variations in neuromorphic systems. The analysis reveals that the major bottleneck in achieving a high‐performance neuromorphic system is the dynamic variation, primarily caused by the intrinsic 1/f noise of the device. As the device area is reduced and the read bias (VRead) is lowered, the intrinsic noise of the FTJs increases, presenting an inherent limitation for implementing area‐ and power‐efficient neuromorphic systems. To overcome this limitation, an adaptive read‐biasing (ARB) scheme is proposed that applies a different VRead to each layer of the neuromorphic system. By exploiting the different noise sensitivities of each layer, the ARB method demonstrates significant power savings of 61.3% and a scaling effect of 91.9% compared with conventional biasing methods. These findings contribute significantly to the development of more accurate, efficient, and scalable neuromorphic systems

Stimulus-Responsive Azobenzene Supramolecules: Fibers, Gels, and Hollow Spheres

Novel, stimulus-responsive supramolecular structures in the form of fibers, gels, and spheres, derived from an azobenzene-containing benzenetricarboxamide derivative, are described. Self-assembly of tris­(4-((<i>E</i>)-phenyldiazenyl)­phenyl)­benzene-1,3,5-tricarboxamide (<b>Azo-1</b>) in aqueous organic solvent systems results in solvent dependent generation of microfibers (aq DMSO), gels (aq DMF), and hollow spheres (aq THF). The results of a single crystal X-ray diffraction analysis of <b>Azo-1</b> (crystallized from a mixture of DMSO and H₂O) reveal that it possesses supramolecular columnar packing along the <i>b</i> axis. Data obtained from FTIR analysis and density functional theory (DFT) calculation suggest that multiple hydrogen bonding modes exist in the <b>Azo-1</b> fibers. UV irradiation of the microfibers, formed in aq DMSO, causes complete melting while regeneration of new fibers occurs upon visible light irradiation. In addition to this photoinduced and reversible phase transition, the <b>Azo-1</b> supramolecules display a reversible, fiber-to-sphere morphological transition upon exposure to pure DMSO or aq THF. The role played by amide hydrogen bonds in the morphological changes occurring in <b>Azo-1</b> is demonstrated by the behavior of the analogous, ester-containing tris­(4-((<i>E</i>)-phenyldiazenyl)­phenyl)­benzene-1,3,5-tricarboxylate (<b>Azo-2</b>) and by the hydrogen abstraction in the presence of fluoride anions