ABSTRACT Controlling electrostatic potential landscapes at the mesoscale is essential for the advancement of adaptive electronic systems. In edge‐gated electrostatic geometries based on ferroionic Li 2.99 B a0.005 OCl films, directional spillover fields and polaron pinning effects generate structured, air‐side electrostatic gradients across centimeter‐scale gaps. A combination of piezoresponse force microscopy (PFM), micrometer‐resolution scanning Kelvin probe (µm‐SKP) analysis, electrochemical impedance spectroscopy (EIS), and temperature‐dependent transport measurements, supported by numerical solutions of the Poisson–Nernst–Planck (PNP) equations, shows dynamic coupling between surface polarization and mobile charge carriers. Apparent surface mobilities in the range of 300–500 cm 2 V −1 s −1 are observed under non‐equilibrium polarization conditions, accompanied by negative static resistance (NSR) and field‐induced carrier asymmetry. These results point to topologically guided conduction paths constrained by interface geometry and electrostatic boundary conditions. Such phenomena enable programmable capacitance zoning and field shaping, with implications for the design of solid‐state transistors and batteries, neuromorphic elements, energy harvesters, and high‐sensitivity sensing platforms.
ABSTRACT Neural probes are essential electrophysiological tools for investigating brain function. Gold (Au) has traditionally been used as the standard signal‐line material due to its high electrical conductivity and excellent biocompatibility. However, global factors, including the COVID‐19 pandemic and associated supply‐chain instabilities, have driven a sharp rise in Au prices over the past decade, substantially increasing the cost of neural probe fabrication. Here, we introduce a neural probe that replaces Au with aluminum (Al), a widely available, low‐cost metal with high electrical conductivity and extensive use in semiconductor manufacturing. To ensure stable electrical performance despite Al's intrinsic susceptibility to oxidation, we developed a Ti/Al/Ni multilayer metal stack engineered to enhance interfacial adhesion, suppress spontaneous oxide formation, and mitigate electrochemical reactivity in electrolyte environments. Using this optimized architecture, the total fabrication cost of a Ti/Al/Ni multilayer neural probe was approximately USD 217—roughly one‐quarter the cost of a probe fabricated with Au under identical process conditions. The resulting probes exhibited robust electrical and chemical stability across multiple evaluations, and in vivo recordings demonstrated neural signal quality comparable to that of conventional Ti/Au neural probes. This approach can expand accessibility to high‐quality neural recording technologies, particularly in resource‐limited research settings.
ABSTRACT Laser‐induced graphene (LIG) has emerged as a sustainable platform for electrochemical sensing due to its low‐cost, chemical‐free, and scalable fabrication. However, integrating metal or metal oxide nanoparticles into LIG remains challenging, as traditional doping strategies are constrained by complex pretreatment procedures and poor metal cation–graphene interfacial interactions, limiting performance. Therefore, simple and efficient strategies for metal‐doped LIG are highly desirable. Herein, we report a single‐step, in situ approach for synthesizing CuO‐decorated LIG using polyimide (PI) as precursor, targeting electrochemical detection of L‐cysteine (L‐Cys). Oxygen plasma pretreatment enhances PI surface hydrophilicity and promotes precursor anchoring, enabling improved nanoparticle dispersion. Subsequent laser irradiation simultaneously induces LIG formation and CuO nanoparticle synthesis. Importantly, this strategy enables control of nanoparticle size by tuning precursor concentration, yielding average diameters of ≈53 nm (50 m m ) and ≈194 nm (100 m m ), a feature rarely explored in LIG systems. Structural and compositional analyses confirm CuO incorporation into the LIG matrix while preserving high conductivity (≈20 Ω sq − 1 ). As a proof of concept, CuO–LIG electrodes exhibit enhanced electrochemical performance for L‐Cys detection, reducing oxidation overpotential to 350 mV vs Ag/AgCl (3 m KCl), achieving a limit of detection of 8.89 µ m and fast response time, only 0.23 ± 0.06 s, demonstrating a simple and effective route for LIG‐based sensors.
ABSTRACT Achieving uniform resistive switching in silicon oxide (SiO x )‐based memristors remains a central challenge due to stochastic electroforming and uncontrolled defect redistribution. Programming the defect landscape through interfacial thermodynamics offers a potential route to suppress this variability. Here we demonstrate a thermodynamic interface‐redox strategy that intrinsically preconditions SiO x memristors and enables forming‐free switching. Deposition of scandium onto SiO x induces a spontaneous interfacial oxidation reaction, forming a stable scandium oxide layer while simultaneously reducing the adjacent SiO x region. This deposition‐driven redox process establishes an equilibrium oxygen‐vacancy reservoir at the interface, effectively defining the defect landscape prior to electrical biasing. The chemically stabilized interfacial layer acts as a predefined nucleation site for conductive filament formation, enabling intrinsic bipolar resistive switching in Sc/SiO x /W devices. The resulting memristors exhibit narrow resistance distributions, endurance exceeding 2 × 10 4 cycles, and retention beyond 10 6 s at 85°C. Unlike conventional oxygen‐scavenging electrodes that rely on dynamic oxygen exchange under high electric fields, the Sc/SiO x interface provides a stable defect reservoir that shifts device operation from stochastic defect generation to controlled vacancy percolation, thereby significantly improving switching uniformity. This interface‐defined defect programming strategy provides a pathway toward reliable SiO x memristors for practical applications.
ABSTRACT The rapid growth of bio‐integrated electronics, ranging from epidermal wearables to deep‐tissue implants, has created an urgent need for energy‐autonomous systems capable of operating without external power. While conventional silicon‐based devices suffer from poor mechanical compliance and low energy efficiency at biological interfaces, organic electrochemical transistors (OECTs) offer a compelling alternative by combining biocompatibility, low‐voltage operation, and intrinsic signal amplification. This review examines the integration of OECTs with energy harvesting technologies, with a particular focus on self‐powered biosensing. We first outline the fundamental operating principles, highlighting how volumetric capacitance and mixed ionic‐electronic conduction enable high transconductance at low voltages, making OECTs well suited for amplifying weak physiological signals. We then review recent advances in materials and device architectures, emphasizing how organic mixed ionic‐electronic conductors govern energy efficiency and operational stability. The electrolyte plays an active role by regulating ion transport and interfacial capacitance, thereby critically influencing device performance under energy‐autonomous conditions. The core discussion focuses on system‐level integration, where OECTs interface with mechanical (triboelectric and piezoelectric), thermal, and optical energy harvesters. Key challenges, including impedance matching and rectification, are analyzed to optimize sensing performance under harvested energy inputs. Finally, we outline future directions toward fully integrated, battery‐free bioelectronic platforms.
ABSTRACT Organic mixed ionic‐electronic conductors (OMIECs) are key components for the next‐generation bioelectronics, albeit with n ‐type materials remaining significantly underrepresented compared to their p ‐type counterparts. Furthermore, reaching low operating voltages alongside high ambient and operational stability remains challenging when employing n ‐type OMIECs in organic electrochemical transistor (OECT)‐based applications. Herein, we report two novel n ‐type polymeric OMIECs, based on an azaisatin and benzodifurandione‐based backbone, incorporating either non‐fluorinated or fluorinated bithiophene donor units. The resulting polymers, obtained via Aldol polymerization, have high electron affinities of 4.5–4.7 eV. Both polymers function in n ‐type accumulation mode OECTs with indications of tunable antiambipolar behavior. The fluorinated polymer displays a low threshold voltage of 0.14 V, while the non‐fluorinated analogue offers excellent operational stability, with the OECT retaining 96% of its initial current after 1800 s of cycling.
ABSTRACT To tackle the alarming generation of electronic waste, sustainable strategies must not be presented blindly without quantitatively assessing their environmental impacts. Here, a nature‐based flexible substrate called Triacetyl Cellulose (TAC) is analyzed as an eco‐friendly alternative to the widely‐used polyimide, not only by demonstrating functional thin‐film sensors but also through substrate recovery and reusability, and evaluation of associated environmental benefits through a life cycle assessment (LCA). Resistance temperature detectors (RTDs) and thermistors are realized on the TAC substrate using Cu, Mo, and AZO contacts, and InGaZnO. The temperature response of Cu‐ and Mo‐based RTDs show negligible hysteresis over multiple thermal cycles, while the AZO‐based RTD and the thermistors show consistent resistance drift. The sensors' mechanical performance is evaluated by bending measurements involving radii down to . We further show TAC recovery by Mo RTD dissolution in deionized water and TAC reusability by another sensor fabrication. Finally, LCA is employed to reliably compare the potential environmental implications of utilizing TAC in comparison with polyimide. Key results show that sensor fabrication on TAC demonstrates lower relative impacts than polyimide in all impact categories, including resource use and climate change, making it a more sustainable substrate choice for the fabrication of thin‐film temperature sensors.
ABSTRACT We report gate‐controlled quantum‐dot transport in a trilayer MoSe 2 device that combines a graphite back gate beneath the active region, a separate global gate for conductive access regions, and local top finger gates. In the low‐backgate regime, bias spectroscopy shows regular Coulomb‐blockade diamonds characteristic of single‐dot transport. As backgate is increased, additional low‐bias structure develops beyond a simple single‐dot pattern, indicating that the electrostatic landscape is reshaped and that a second dot becomes active in transport. In the higher‐backgate regime, plunger‐gate tuning and two‐gate measurements establish a gate‐reconfigurable double‐dot configuration with two non‐equivalent dots whose relative alignment and interdot coupling evolve with gate voltage. These results indicate that trilayer MoSe 2 supports electrically reconfigurable single‐ and double‐dot transport in the present device architecture.
ABSTRACT Despite extensive research on quantum dot light‐emitting diodes, the underlying charge transport mechanisms remain poorly understood. Previously, we have demonstrated that the hole transport in quantum dot (QD) thin films is trap‐free and space‐charge‐limited. However, the electron transport mechanism remains unexplored. In this study, we systematically investigate the electron transport in red, green, and blue (RGB) core/multi‐shell QD thin films through the analysis of the current density‐voltage ( J–V ) measurements using single‐carrier devices. Our findings reveal that the electron transport in these QD thin films is significantly impeded by the presence of electron traps, which exhibit a Gaussian energy distribution within the bandgap. Notably, the electron trap distributions observed across different QD systems exhibit a high degree of similarity. Specifically, these traps have a concentration of ∼1 × 10 23 m −3 , with the trap center energy level positioned at approximately 4.0 eV below the vacuum level. Furthermore, the width of the energy distribution of the trapping sites is comparable to that of the QD transport sites. By correlating the surface‐to‐volume ratio with the number of traps, we propose that the traps are located at the core‐shell interface and arise from uncoordinated atoms. Therefore, increasing the core size can effectively suppress the trapping effect.
ABSTRACT Programmable metasurfaces enable agile electromagnetic beam shaping, yet the inverse design of dense binary apertures is complicated by feed illumination, local coupling, finite aperture effects, and mode dependent state statistics. A physics informed generative surrogate framework is developed for real time beamforming with full wave validation. The framework integrates a conditional state matrix generator, a parametric aperture physics surrogate with hard routed residual experts, two stage NSGA‐II optimization, and CST verification. The generator achieves 96.67% binary accuracy and a 94.47% F1 score. The best predictor gives a test RMSE of 1.108 dBi, an MAE of 0.549 dBi, and a peak gain MAE of 0.114 dB. Across 137 optimized full wave validation cases, the mean peak gain bias remains close to ‐0.13 dB. For 35 paired real time/final cases, the refined search improves the full wave target region gain by 2.943 dB on average and the peak gain by 0.573 dB, indicating that the surrogate can support practical metasurface beam optimization.
ABSTRACT Memristive Pr 0.7 Ca 0.3 MnO 3 (PCMO) heterostructures exhibit area‐dependent resistive switching via a valence change mechanism, making them promising for neuromorphic architectures. A major challenge in PCMO‐based memory is higher‐dimensional lattice defects that affect oxygen‐vacancy migration and concentration. This study mitigates these defects using highly conductive amorphous PCMO fabricated via a CMOS back‐end‐of‐line‐compatible process and compares it with low‐conductive amorphous and polycrystalline PCMO. The resistance differences are attributed to changes in electronic mobility, based on the analysis of short‐ and long‐range order, Mn–O hybridization, and Mn valence state. AlO x /qa‐PCMO devices showed the highest ON/OFF ratio compared to low‐conductive amorphous and polycrystalline PCMO, because the field‐accelerated oxygen vacancy movement switches the mechanism from Poole–Frenkel emission in the LRS to trap‐assisted tunneling in the HRS. The mechanism change was identified by systematically analyzing the I–V asymmetry, device band diagrams for different PCMO types, and shape changes in the I–V curve fits. The band diagrams were calculated from the measured bandgaps and work functions of the different PCMO types. Analysis of the electric field distribution in the devices showed a clear correlation between the pre‐switching field strength in AlO x and the resulting ON/OFF ratio.
ABSTRACT Memristors exhibiting both volatile and non‐volatile resistive switching (RS) behaviors hold significant potential for their utilization as artificial neurons and synapses in neuromorphic computing systems, respectively. Inkjet printing presents an economical, low‐material‐waste, and compatible process for the fabrication of solution‐based memristors, which are essential for flexible, wearable and biocompatible applications. However, inkjet‐printed memristors typically exhibit low endurance (below 10 4 cycles) and high switching currents (above 100 µA), both of which represent critical limitations for the practical implementation and low‐power operation of neuromorphic computing systems. In this work, a hexagonal boron nitride (h‐BN) based memristor formulated via liquid phase exfoliation (LPE) and fabricated with inkjet printing demonstrates exceptional electrical performance with a remarkable endurance of 2.2 million cycles at very low currents (below 1 µA) in a volatile regime under a current‐driven approach. This result surpasses the highest endurance reported to date on inkjet‐printed‐based memristors, surpassing the threshold of one million cycles. At higher currents (above 10 µA), the same devices exhibit stable non‐volatile RS with an endurance of 70 000 cycles. This study not only demonstrates the remarkable performance of the designed memristors, but also opens new avenues for current‐driven memristive electrical characterization and neuromorphic applications.
ABSTRACT Low‐dimensional perovskite photodetectors attract significant attention due to their tunable optoelectronic properties, quantum confinement effects and solution processability. Among them, phenethylammonium lead bromide (PEA2PbBr4) is more stable than its 3D counterparts. However, degradation under environmental stress remains an obstacle to practical applications, particularly with prolonged exposure to temperature and humidity. This study systematically evaluates the impact of these stressors on the morphology, crystallinity, and optoelectronic performance of PEA2PbBr4 photodetectors. The impact of the halogen‐bonding additive 1,4‐TFIB (1,4‐diiodotetrafluorobenzene) on the stability of the devices is also considered. Here, the devices were subjected to an increase in temperature (20°C–120°C) and humidity (40%RH–98%RH) in five steps, with each condition maintained for two days. Morphological and structural analyses are performed, as well as optoelectronic analyses under UV light and X‐ray irradiation. The results show that, while pristine films undergo significant physical degradation and material loss at elevated temperature and humidity, the incorporation of 1,4‐TFIB significantly enhances material endurance. Although the additive reduces the photocurrent signal of the device under UV and X‐ray irradiation, it mitigates physical loss of the material and maintains structural integrity in harsh conditions, thereby enhancing device longevity in optoelectronic sensing applications.
ABSTRACT X‐ray total ionization dose (TID) significantly modifies synaptic plasticity in SnO‐based volatile memristors, a device class promising for neuromorphic computing in radiation‐exposed environments. We further observe that synaptic operation becomes more stable when training is initiated after a reset, indicating a protocol‐dependent mitigation of variability. Device‐parameterized convolutional neural network simulations indicate that nonlinearity and epoch‐to‐epoch variation both decrease in irradiated devices, leading to higher training accuracy (≈80% after 200 epochs) than pristine counterparts (<50%); confusion‐matrix analysis further highlights nonlinearity as a more critical determinant of performance than raw dynamic range. To interpret this phenomenon, we propose a conduction mechanism that accounts for potentiation, relaxation, and depression dynamics under irradiation. These findings show that radiation‐induced modifications—often considered detrimental—can be harnessed to strengthen key synaptic metrics in volatile memristors. We highlight a design trade‐off in which linearity and stability may be prioritized over raw dynamic range for learning accuracy, and this positions TID‐tuned memristors as candidates for robust neuromorphic hardware operating in extreme environments.
ABSTRACT Advances in soft electronics and soft biorobotics have accelerated progress in advanced biomedical engineering. This new frontier motivates development of next‐generation healthcare technologies focused on minimally invasive robotic surgery and continuous real‐time physiological monitoring through wearable, implantable, and personalized devices. Among different physiological parameters, pressure represents a critical factor, extensively measured using diverse sensing mechanisms such as piezoresistive, capacitive, piezoelectric, optical, triboelectric and other different modalities. The integration of these sensing principles with emerging sustainable materials with advanced fabrication techniques has enabled the creation of flexible, stretchable, and conformable pressure sensors capable of adapting to unconventional surfaces. This literature review comprehensively summarizes up‐to‐date progress in pressure sensing mechanisms, materials, and structural design strategies, highlighting their potential towards developing advanced biomedical applications. Furthermore, it discusses current challenges, and future perspectives for developing high‐performance, biocompatible, and sustainable pressure sensors that will advance healthcare monitoring.
ABSTRACT Zinc oxide (ZnO) nanowires (NWs) are widely investigated for ultraviolet (UV) photodetectors (PDs) due to their wide direct bandgap, high exciton binding energy, and large surface‐to‐volume ratio enabling efficient light–matter interaction and carrier modulation. This review presents a device‐physics‐oriented analysis of recent advances in ZnO NW‐based UV photodetectors, emphasizing the interplay between nanostructure synthesis, interface engineering, and carrier transport mechanisms. Three main device architectures—photoconductive, Schottky barrier, and metal–semiconductor–metal (MSM)—are compared in terms of operating principles, performance trade‐offs, and fundamental limitations. Key enhancement strategies, including doping, surface passivation, plasmonic modification, and hybrid heterostructure integration, are discussed with respect to improvements in responsivity, response speed, and stability. Recent progress in flexible, self‐powered, and multifunctional UV photodetectors is also highlighted. Current challenges, including defect control, interface engineering, reproducibility, and scalable fabrication, are critically assessed. By establishing a unified structure–property–device physics framework, this review provides insights into the fundamental limitations of ZnO NW UV photodetectors and design guidelines for next‐generation optoelectronic devices.
ABSTRACT Memristive devices integrating non‐volatile memory and artificial synaptic functionalities are promising candidates for neuromorphic in‐memory computing. However, stochastic and non‐linear evolution of conductive filaments often hinders stable and gradual synaptic weight updates. Here, we investigate pulse‐protocol optimization in an Au/MoO3/TiO2/FTO bilayer‐oxide memristor to achieve both digital memory operation and analog conductance modulation. The switching characteristics evolve from interface‐driven self‐rectifying behavior prior to electroforming, to filament‐governed non‐volatile bipolar resistive switching. The device exhibits good endurance (25,000 cycles) and retention (1000 s), fast switching, low variability, operational stability up to 60°C, and reliable performance over a testing duration of 70 weeks. Furthermore, the RESET process exhibits quantized conductance features, indicating atomic‐scale constricted conduction pathways across the switching layers. Importantly, the optimized combinational voltage pulse scheme enables gradual and controlled conductance evolution, resulting in highly linear and stable potentiation– depression characteristics. The pulse‐engineered synaptic linearity further enables a significant ∼20% enhancement in artificial neural network inference accuracy for handwritten digit recognition. This work highlights pulse‐protocol control combined with oxide‐bilayer architecture as an effective strategy for developing multifunctional memristors for neuromorphic computing applications.
ABSTRACT To enable compact quantum computing systems, cryogenically compatible CMOS‐based non‐volatile memories are required. In this work, we investigate 1‐transistor–1‐resistor (1T1R) resistive random‐access memory (RRAM) devices over an extended temperature range, including previously unexplored cryogenic regimes. To enhance storage density, we explore a multilevel‐cell approach via multilevel programming. As temperature decreases, the low‐resistance state (LRS) effective conductance increases, improving state separation but also leading to higher LRS currents and increased reset voltages required for reliable switching to the high‐resistance state (HRS), resulting in incomplete filament rupture and a broader HRS distribution. Through independent characterization of the access nMOS transistor, we identify transistor temperature dependence as the dominant factor governing LRS evolution, while extraction of the intrinsic metal–insulator–metal (MIM) behavior reveals an opposite trend, with decreasing conductivity at lower temperatures. Based on these insights, we implement an optimized programming strategy for cryogenic operation by tuning the nMOS gate bias during set, reducing LRS currents, particularly in intermediate and high conductance states, while preserving state separation, narrowing the HRS distribution, and lowering reset voltages. Overall, this work establishes a robust and scalable approach for reliable 1T1R operation at cryogenic temperatures and provides a key step toward nonvolatile memory integration in quantum computing architectures.
ABSTRACT Organic electrochemical transistors (OECTs) require antifouling channel materials to operate stably in biological environments. Here, we demonstrate a simple strategy to introduce antifouling functionality into PEDOT:PSS‐based OECTs using zwitterionic polymers. Homo‐, random‐, and block‐type zwitterionic polymers are synthesized and mixed with PEDOT:PSS via solution processing, enabling the fabrication of blend films without additional steps. Structural and spectroscopic analyses show that the zwitterionic polymers are retained within the films, maintaining the doping state and crystalline structure of PEDOT:PSS. Instead, differences in polymer architecture produce distinct structural features within the preserved core–shell PEDOT:PSS framework, including variations in the apparent shell thickness and, for zwitterionic (co)monomer components, the formation of an outer polymer‐rich region. These structural differences directly influence charge transport. Electrochemical and OECT measurements reveal reductions in volumetric capacitance and transconductance, mainly due to decreased apparent mobility. Protein adsorption studies further show reduced device degradation upon exposure to two proteins: bovine serum albumin and fibronectin. This blending strategy provides a practical route to antifouling, solution‐processable OECT materials for bioelectronic interfaces.
ABSTRACT Indium gallium zinc oxide (IGZO) is a well‐established channel material for thin‐film transistors and has also emerged as a promising active layer for memristor applications. Further, IGZO memristors can exhibit both abrupt and gradual switching behaviors, which offer enhanced adaptability for future memory and neuromorphic computing systems. In this study, we have systematically modulated the surface defect states in IGZO thin films through Ar‐plasma and ultraviolet ozone (UV‐O 3 ) treatments, and investigated their influence on the memristive switching characteristics in a W/IGZO/Pt device architecture. Notably, Ar‐plasma enabled forming‐free abrupt switching behavior, while UV‐O 3 led to a transition to gradual switching. The devices were subjected to 10 3 direct‐current sweep cycles and 10 4 s of retention testing. Especially the Ar‐plasma and untreated reference devices showed stable behavior, while the UV‐O 3 showed initial drifts in both measurements. Additionally, the absolute switching voltages of all samples are ≤1 V. These results demonstrate that the switching behavior of IGZO‐based memristors can be effectively tuned through simple surface treatments while maintaining reliable device performance, underscoring the strong potential of IGZO as a versatile material for next‐generation memristor technologies.
