As the demand for advanced computational systems capable of handling large data volumes rises,nano-electronic devices,such as memristors,are being developed for efficient data processing,especially in reservoir comput...As the demand for advanced computational systems capable of handling large data volumes rises,nano-electronic devices,such as memristors,are being developed for efficient data processing,especially in reservoir computing(RC).RC enables the processing of temporal information with minimal training costs,making it a promising approach for neuromorphic computing.However,current memristor devices of-ten suffer from limitations in dynamic conductance and temporal behavior,which affects their perfor-mance in these applications.In this study,we present a multilayered indium-tin-oxide(ITO)/ZnO/indium-gallium-zinc oxide(IGZO)/ZnO/ITO memristor fabricated via radiofrequency sputtering to explore its fil-amentary and nonfilamentary resistive switching(RS)characteristics.High-resolution transmission elec-tron microscopy confirmed the polycrystalline structure of the ZnO/IGZO/ZnO active layer.Dual-switching modes were demonstrated by controlling the current compliance(I_(CC)).In the filamentary mode,the memristor exhibited a large memory window(10^(3)),low-operating voltages(±2 V),excellent cycle-to-cycle stability,and multilevel switching with controlled reset-stop voltages,making it suitable for high-density memory applications.Nonfilamentary switching demonstrated stable on/off ratios above 10,en-durance up to 102 cycles,and retention suited for short-term memory.Key synaptic behaviors,such as paired-pulse facilitation(PPF),post-tetanic potentiation(PTP),and spike-rate dependent plasticity(SRDP)were successfully emulated by modulating pulse amplitude,width,and interval.Experience-dependent plasticity(EDP)was also demonstrated,further replicating biological synaptic functions.These tempo-ral properties were utilized to develop a 4-bit reservoir computing system with 16 distinct conductance states,enabling efficient information encoding.For image recognition tasks,convolutional neural net-work(CNN)simulations achieved a high accuracy of 98.45%after 25 training epochs,outperforming the accuracy achieved following artificial neural network(ANN)simulations(87.79%).These findings demon-strate that the multilayered memristor exhibits high performance in neuromorphic systems,particularly for complex pattern recognition tasks,such as digit and letter classification.展开更多
To enhance the repair of peripheral nerve injuries(PNIs),various nerve guidance conduits(NGCs)have been developed by integrating topological,biochemical,and cellular cues.Hydrogel-based NGCs are particularly promising...To enhance the repair of peripheral nerve injuries(PNIs),various nerve guidance conduits(NGCs)have been developed by integrating topological,biochemical,and cellular cues.Hydrogel-based NGCs are particularly promising owing to their unique tissue-mimicking characteristics,such as high water content,softness,and porosity.However,their weak mechanical strength and insufficient biological activity limits their application.Therefore,in this study,we aimed to develop NGCs by encapsulating human umbilical cord-derived mesen-chymal stem cells(ucMSCs)in double-network(DN)hydrogel conduits for improved peripheral nerve regen-eration.A DN hydrogel,fabricated via sequential photo-and ionic-crosslinking of 15%gelatin methacrylate and 1%alginate,exhibited excellent rheological and mechanical properties,including fatigue resistance,suture retention,and kink resistance.In a rat sciatic defect model,ucMSC-encapsulated DN NGCs demonstrated significantly improved functional and structural recovery compared to medical silicone and non-cellular hydrogel NGCs.Quantitative assessments revealed that the MSC-laden NGC group exhibited superior func-tional recovery,as indicated by footprint analysis,electromyography,thermal withdrawal latency,and muscle weight restoration.Moreover,histological analysis and transmission electron microscopy confirmed significantly enhanced axonal regeneration and myelination in the MSC-laden NGC group(axon diameter and myelin thickness).Overall,our results indicate that the MSC-laden hydrogel NGCs can serve as a novel platform to treat PNIs and function as effective stem cell delivery scaffolds for the regeneration of various tissues,such as the skin,tendons,and muscles.展开更多
基金supported by the National R&D Pro-gram through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(Nos.RS-2024-00356939 and RS-2024-00405691).
文摘As the demand for advanced computational systems capable of handling large data volumes rises,nano-electronic devices,such as memristors,are being developed for efficient data processing,especially in reservoir computing(RC).RC enables the processing of temporal information with minimal training costs,making it a promising approach for neuromorphic computing.However,current memristor devices of-ten suffer from limitations in dynamic conductance and temporal behavior,which affects their perfor-mance in these applications.In this study,we present a multilayered indium-tin-oxide(ITO)/ZnO/indium-gallium-zinc oxide(IGZO)/ZnO/ITO memristor fabricated via radiofrequency sputtering to explore its fil-amentary and nonfilamentary resistive switching(RS)characteristics.High-resolution transmission elec-tron microscopy confirmed the polycrystalline structure of the ZnO/IGZO/ZnO active layer.Dual-switching modes were demonstrated by controlling the current compliance(I_(CC)).In the filamentary mode,the memristor exhibited a large memory window(10^(3)),low-operating voltages(±2 V),excellent cycle-to-cycle stability,and multilevel switching with controlled reset-stop voltages,making it suitable for high-density memory applications.Nonfilamentary switching demonstrated stable on/off ratios above 10,en-durance up to 102 cycles,and retention suited for short-term memory.Key synaptic behaviors,such as paired-pulse facilitation(PPF),post-tetanic potentiation(PTP),and spike-rate dependent plasticity(SRDP)were successfully emulated by modulating pulse amplitude,width,and interval.Experience-dependent plasticity(EDP)was also demonstrated,further replicating biological synaptic functions.These tempo-ral properties were utilized to develop a 4-bit reservoir computing system with 16 distinct conductance states,enabling efficient information encoding.For image recognition tasks,convolutional neural net-work(CNN)simulations achieved a high accuracy of 98.45%after 25 training epochs,outperforming the accuracy achieved following artificial neural network(ANN)simulations(87.79%).These findings demon-strate that the multilayered memristor exhibits high performance in neuromorphic systems,particularly for complex pattern recognition tasks,such as digit and letter classification.
基金supported by a grant from the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT,and Future Planning(RS-2023-NR076958 and RS-2021-NR057371).
文摘To enhance the repair of peripheral nerve injuries(PNIs),various nerve guidance conduits(NGCs)have been developed by integrating topological,biochemical,and cellular cues.Hydrogel-based NGCs are particularly promising owing to their unique tissue-mimicking characteristics,such as high water content,softness,and porosity.However,their weak mechanical strength and insufficient biological activity limits their application.Therefore,in this study,we aimed to develop NGCs by encapsulating human umbilical cord-derived mesen-chymal stem cells(ucMSCs)in double-network(DN)hydrogel conduits for improved peripheral nerve regen-eration.A DN hydrogel,fabricated via sequential photo-and ionic-crosslinking of 15%gelatin methacrylate and 1%alginate,exhibited excellent rheological and mechanical properties,including fatigue resistance,suture retention,and kink resistance.In a rat sciatic defect model,ucMSC-encapsulated DN NGCs demonstrated significantly improved functional and structural recovery compared to medical silicone and non-cellular hydrogel NGCs.Quantitative assessments revealed that the MSC-laden NGC group exhibited superior func-tional recovery,as indicated by footprint analysis,electromyography,thermal withdrawal latency,and muscle weight restoration.Moreover,histological analysis and transmission electron microscopy confirmed significantly enhanced axonal regeneration and myelination in the MSC-laden NGC group(axon diameter and myelin thickness).Overall,our results indicate that the MSC-laden hydrogel NGCs can serve as a novel platform to treat PNIs and function as effective stem cell delivery scaffolds for the regeneration of various tissues,such as the skin,tendons,and muscles.
