Flexible Switching Research Articles

Flexible switch matrix addressable electrode arrays with organic electrochemical transistor and pn diode technology

Due to their effective ionic-to-electronic signal conversion and mechanical flexibility, organic neural implants hold considerable promise for biocompatible neural interfaces. Current approaches are, however, primarily limited to passive electrodes due to a lack of circuit components to realize complex active circuits at the front-end. Here, we introduce a p-n organic electrochemical diode using complementary p- and n-type conducting polymer films embedded in a 15-μm -diameter vertical stack. Leveraging the efficient motion of encapsulated cations inside this polymer stack and the opposite doping mechanisms of the constituent polymers, we demonstrate high current rectification ratios (105\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${10}^{5}$$\\end{document}) and fast switching speeds (230 μs). We integrate p-n organic electrochemical diodes with organic electrochemical transistors in the front-end pixel of a recording array. This configuration facilitates the access of organic electrochemical transistor output currents within a large network operating in the same electrolyte, while minimizing crosstalk from neighboring elements due to minimized reverse-biased leakage. Furthermore, we use these devices to fabricate time-division-multiplexed amplifier arrays. Lastly, we show that, when fabricated in a shank format, this technology enables the multiplexing of amplified local field potentials directly in the active recording pixel (26-μm diameter) in a minimally invasive form factor with shank cross-sectional dimensions of only 50×8 μm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mu m}^{2}$$\\end{document}.

Two-stage optimization of hydrogen and storage coordination for a multi-region flexible intermodal multi-energy port system

To address the issue of imbalanced electricity and hydrogen supply and demand in the flexible multi-energy port area system, a multi-regional operational optimization and energy storage capacity allocation strategy considering the working status of flexible multi-status switches is proposed. Firstly, based on the characteristics of the port area system, models for system operating costs, generation equipment, energy storage devices, flexible multi-status switches, and others are established. Secondly, the system is subjected to a first-stage optimization, where different regions are optimized individually. The working periods of flexible multi-status switches are determined based on the results of this first-stage optimization, targeting the minimization of the overall daily operating costs while ensuring 100% integration of renewable energy in periods with electricity supply-demand imbalances. Subsequently, additional constraints are imposed based on the results of the first-stage optimization to optimize the entire system, obtaining power allocation during system operation as well as power and capacity requirements for energy storage devices and flexible multi-status switches. Finally, the proposed approach is validated through simulation examples, demonstrating its advantages in terms of economic efficiency, reduced power and capacity requirements for energy storage devices, and carbon reduction.

Programmable inverse-designed acoustic coding metasurfaces for multifunctional broadband reflection

In this paper, we develop tunable reflection-type broadband acoustic coding metasurfaces (BACMs) using a bottom-up topology optimization method. These metasurfaces enable flexible configuration switching between the antiphase coding units of “0” and “1” across a wide frequency range through electromagnetic regulation. By introducing a customized dispersion design, the optimized structure exhibits broadband properties. The optimized coding units consist of irregular air channels and connected air cavities. The coding bits of “0” and “1” show a constant opposite phase difference over a wide frequency range through the coupling resonances. By adjusting the electromagnets, arbitrary coding sequences in the BACMs can be rapidly reconstructed. We numerically and experimentally demonstrate the acoustic focusing and splitting properties within the frequency range of 2.2 kHz–4.4 kHz.

A dual functional tunable terahertz metamaterial absorber based on vanadium dioxide.

A dual-functional switchable metamaterial absorber (MMA) based on vanadium dioxide (VO2), which achieves flexible switching between broadband absorption and four-band absorption by adjusting the VO2 conductivity, was proposed. The device has a broadband absorption function when VO2 is in the metal phase, and the conductivity is 3 × 105 S m-1. Numerical simulation shows that the absorption rate of the device reaches over 90% in the frequency range of 3.36-6.98 THz. The absorber exhibits polarization insensitivity and wide-angle absorption to transverse electric (TE) and transverse magnetic (TM) waves. When VO2 is in the insulator phase, and the conductivity is 3 × 102 S m-1, the device switches to a narrowband absorber with a band-efficient absorption function. Numerical simulation shows that the device has an absorption rate of 99.7% at 2.39 THz, 98.3% at 2.83 THz, 95.6% at 3.84 THz, and 96.1% at 4.61 THz. It can be used as a sensor with high sensitivity. In addition, to verify the absorption mechanism of the absorber, we introduced impedance matching theory to analyze the device. Finally, the influence of structural parameters on the performance of resonators was investigated. Through the joint action of multi-layer structures, the proposed MMA concentrates broadband and narrowband absorption functions on one device, achieving flexible switching between tasks without changing the structure. The switchable metamaterial absorber designed through simple tuning methods has broad application prospects in stealth technology and thermal emitters. It provides a wide range of ideas for the design of terahertz functional devices.

Development of a Coaxial Dual-Coil Induction Heating System With a Composite Bridge-Type Inverter and a Flexible Switching Mechanism

Development of a Coaxial Dual-Coil Induction Heating System With a Composite Bridge-Type Inverter and a Flexible Switching Mechanism

Switchable ultra-broadband absorption and polarization conversion terahertz metasurface

Metasurfaces can realize flexible modulation of electromagnetic waves at the wavelength level. However, the reported functions of metasurface are usually fixed and cannot be changed, once its structural design is completed. The designed metasurface cannot meet the requirements for flexible regulation of terahertz waves. We find that the phase change material of vanadium dioxide can achieve a transition from insulating state to metallic state through thermal, electrical, or light excitation, and the phase transition of this material is reversible. Therefore, using vanadium dioxide to form a composite metasurface can achieve dynamic modulation of terahertz waves. In this study, we propose a terahertz metasurface with switchable broadband absorption and polarization conversion. The proposed metasurface is composed of a 9-layer structure stacked from bottom to top with a combination pattern of different dielectric layers. By adjusting the conductivity of vanadium dioxide, the designed metasurface can achieve flexible switching between terahertz wave absorption function and polarization conversion function. When the vanadium dioxide is in the metal state, the designed metasurface behaves as a broadband absorber with an absorption rate of more than 90% in a range of 6.32–18.06 THz and a relative bandwidth of 96.3%. When the vanadium dioxide is in the insulated state, the designed structure acts as a polarization converter in a frequency range of 2.41–3.42 THz, 4.78–7.48 THz, and 9.53–9.73 THz, respectively, with a polarization conversion rate of over 90%. We believe that this metasurface structure will have good applications in the fields of terahertz wave detection, terahertz switches, terahertz filtering, terahertz communication, and terahertz sensing.

Design of a Testing Tool Based on Fault Injection for Functional Safety

ISO 26262 provides testing requirements for functional safety development and testing to mitigate unacceptable risks arising from system functional failures. Fault injection plays a vital role in assessing system robustness and validating the efficacy of safety mechanisms. This paper explores the fault types and implementation process of fault injection in the context of functional safety confirmation and validation. A fault injection board specifically designed for electrical faults is developed and integrated with Controller Area Network (CAN) messages to verify the effectiveness and correctness of safety mechanisms. The proposed approach offers the advantages of flexible switching and ease of control, making it a valuable tool in ensuring the functional safety of automotive systems.

Analysis and Design of MBCFET and Their Circuit Application in Current Mirror and DRAM

This research paper addresses the challenges associated with transistor downscaling, particularly short channel effects (SCEs) in conventional silicon metal-oxide-semiconductor field-effect transistors (Si MOSFETs), and introduces Multi-Bridge-Channel MOSFETs (MBCFETs) as a potential solution. This study explores their attributes, emphasizing flexibility and faster switching, and comprehensively examines device parameters, fabrication processes, and simulation frameworks, offering a detailed analysis of critical factors influencing MBCFET performance. Investigating the intricate relationship between nanosheet dimensions and device characteristics, the research provides insights for optimized design and integration into future semiconductor technologies. The research looks at how the gate electrode's work function, the nanosheets' thickness and count, and the different types of doping affect important device properties such as transconductance, drive current, OFF-state current, and threshold voltage. Furthermore, the study is being carried out to form a current mirror and DRAM circuit by using the proposed MBCFET. This study demonstrates the transformative potential of MBCFETs in high-performance electronic applications.

Process control of rice protein enzymolysis by field monitoring

By devising a novel near-infrared (NIR) in-situ online monitoring system, this study proposed a new process control method for rice protein (RP) enzymatic hydrolysis in order to address the challenge of monitoring certain chemical indices in real-time. The endpoint of the enzymatic hydrolysis reaction and the flexible switching point of dual-enzyme hydrolysis were determined through real-time spectrum collection. Correction and prediction models were constructed to predict the angiotensin I-converting enzyme (ACE) inhibitory activity of RP hydrolysis as well as the endpoint and the dual-enzyme flexible switching point at different substrate concentrations in an attempt to establish the new control system. At the RP substrate concentrations of 35, 40, and 45 g/L, the R2 of predicted and measured ACE inhibitory activity values under hydrolysis with a single alcalase were 0.8852, 0.8360, and 0.8613, respectively. In addition, the ACE inhibitory activity of dual-enzyme hydrolysis showed a high growth trend before and after the flexible switching point, and the hydrolysis time was significantly shortened at the same endpoint threshold as that of single alcalase hydrolysis. The results indicated that this method is capable of accurately determining and regulating the endpoint and adaptable transition point of RP hydrolysis. Consequently, this approach holds promise for the regulation of food basic materials during large-scale processing operations.

Flexible SnO2–MoS2 based memristive device exhibiting stable and enhanced memory phenomenon

Flexible non-volatile memory devices have been gaining interest in expanding the digital data storage world. Due to the burgeoning advancement in the healthcare industry, the Internet of Things, and wearable electronics, the demand for ultra-thin, low-power, and flexible memory is increasing. Further, the advancement of synthesis procedures for two-dimensional nanomaterials having better optical, electrical, and mechanical strength with flexibility has fuelled the flexible memory device area, as commonly used flash memory is approaching its physical limit. In this context, the present work reports the flexible resistive switching memory device based on pure molybdenum disulfide (MoS2) and tin oxide (SnO2) based nanocomposite powder synthesized using the simple hydrothermal process. The nanocomposite formation was characterized using x-ray diffraction and Raman spectroscopic techniques. The memory device was fabricated by spin-coating the pure MoS2, pure SnO2, and MoS2–SnO2 nanocomposite film over the ITO-PET flexible substrate. The device was completed by thermally evaporating the thin Al layer through a shadow mask. It was found that MoS2–SnO2 based memory devices exhibited improved switching performance having a higher I ON/I OFF ratio, and lower switching voltage in comparison to pure MoS2 and pure SnO2-based devices (I ON/I OFF ratio ∼100, V = 0.5 V). Furthermore, to check the stability and cyclic performance of the fabricated device, the retention and endurance test was also performed, and the MoS2–SnO2 device retained the HRS and LRS states up to 2 × 103s and showed stable performance up to 100 switching cycles without much degradation, respectively. It should be mentioned that the presently proposed ReRAM device based on SnO2 and MoS2 with flexible and low-power features had excellent potential for use in the wearable device industry.

Enhancing vehicle/airborne displays with beam steering technology for improved viewing angles

ABSTRACT For vehicles or airborne displays, the limited space and arrangement of operating devices in the cockpit often result in drivers having a certain off-axis viewing angle with the display. This leads to a noticeable degradation in performance parameters such as brightness and colour shift compared to the vertical viewing angle. A beam steering technology applicable to the display field is presented, which simultaneously improves the performance of vehicle/airborne displays in both the large and off-axis viewing angles. When the usage scenario changes, such as acceleration, deceleration, turning, the proposed technology allows for the flexible switching of display modes, effectively aligning the high-brightness and low colour shift high-quality display to the corresponding viewing angle. The simulation results show that the viewing angle performance of displays are effectively improved, which demonstrates that the proposed technology has a promising application prospect to substantially enhance viewers’ visual experience.

A Coordinated Reclosing Strategy for Maintained Transformer in Offshore Wind Power Systems

Offshore wind power generation system needs to consider the maintained transformers to reclose. The close loop operation can meet the requirement for reclosing the maintained transformer and maximize the use of wind resources without disconnecting wind turbines. However, close loop operation will cause system damping which can easily cause system instability and protection maloperations. To suppress close loop current damping, a flexible reclosing strategy is proposed that coordinates control of the main bus switch and transformer-connected flexible switch which consists of a damping buffer branch and pass branch. The coordinated control of switches realizes the optimized reclosing state of the maintained transformer. Finally, case studies are established in PLECS simulation software to evaluate the effectiveness of the proposed flexible reclosing strategy to eliminate the reclose damping oscillation for maintained transformers in offshore wind power generation systems.

Flexible Switching Pressure Sensors with Fast Response and Less Bending-Sensitive Performance Applied to Pain-Perception-Mimetic Gloves.

A strategy is proposed herein for preparing a flexible switching piezoresistive pressure sensor, which has a bridge-like structure and inverted micropyramids (IMPs) on its lower conductive substrate. The sensor substrates were prepared by injection compression molding (an industrial manufacturing process) using thermoplastic polyurethane (TPU; an industrial grade polymer). The designed bridge-like structure enables the sensor to obtain a pressure threshold. The flexibility of upper and lower TPU substrates allows them to contact quickly when pressed, and so the sensor exhibits a fast response (as short as 2 ms) and can respond to both static force and dynamic force (up to 50 Hz frequency), which are prominent for the sensor made from TPU. The sensor exhibits less bending-sensitive performance, which is attributed to the conformality of the upper and lower substrates and lower strain on the lower substrate with the IMP under bending. The sensor can amplify signal response at the monitoring limit (the relative resistance change is up to 46%). It can achieve a higher sensitivity in different low-pressure ranges by changing the gap of the bridge-like structure. Moreover, the sensor can obviously and steadily respond to an additional very low pressure under preloading and exhibits good durability performance. As the sensor has a pressure threshold similar to the human pain perception process, a pain-perception-mimetic glove that can identify the external mechanical stimuli but reduces the interference of finger bending is prepared, displaying potential applications of the flexible switching sensor in intelligent wearable protectors.

The HPA and SAM axis mediate the impairment of creativity under stress.

With the ever-changing social environment, individual creativity is facing a severe challenge induced by stress. However, little is known regarding the underlying mechanisms by which acute stress affects creative cognitive processing. The current research explored the impacts of the neuroendocrine response on creativity under stress and its underlying cognitive flexibility mechanisms. The enzyme-linked immuno sorbent assay was employed to assess salivary cortisol, which acted as a marker of stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis. Eye blink rate (EBR) and pupil diameter were measured as respective indicators of dopamine and noradrenaline released by the activation of the sympathetic-adrenal-medullary (SAM) axis. The Wisconsin card task (WCST) measured cognitive flexibility, while the alternative uses task (AUT) and the remote association task (RAT) measured separately divergent and convergent thinking in creativity. Results showed higher cortisol increments following acute stress induction in the stress group than control group. Ocular results showed that the stress manipulation significantly increased EBR and pupil diameter compared to controls, reflecting increased SAM activity. Further analysis revealed that stress-released cortisol impaired the originality component of the AUT, reducing cognitive flexibility as measured by perseverative errors on the WCST task. Serial mediation analyses showed that both EBR and pupil diameter were also associated with increased perseverative errors leading to poor originality on the AUT. These findings confirm that physiological arousal under stress can impair divergent thinking through the regulation of different neuroendocrine pathways, in which the deterioration of flexible switching plays an important mediating role.

Techno-economic assessment of the solar-assisted heat pump latent heat thermal energy storage system for water heating

A novel solar-assisted heat pump heating system including the latent heat thermal energy storage component that enables flexible switching between different connection modes was developed in this study to provide a cost-effective and energy-efficient solution for hot water supply. The feasibility, energy efficiency, and economic performance of the system under different design parameters and operation modes were evaluated via the experimental validated numerical model of the heating system. The end-user loads and meteorological parameters highly affected the system performance under the same design scheme. The optimal system configuration and component size for promoting renewable energy penetration and decreasing electricity cost were further determined. A certain increment in the collection area substantially benefits system performance, resulting in an approximately 56.6 % reduction in energy consumption. The larger capacity of the heat pump reflects a slight improvement in the system performance; however, it would require a longer payback period. Compared with the single solar and air heat source, the energy consumption of the hybrid heat source system declined by 26.6 % and 68.0 %, respectively. The system implementing the demand-side management proved to be a more profitable solution, exhibiting a low carbon emission of 188.1 kg, significant potential to flatten peak load, and a large lifecycle cost saving of $1834.64.

Flexible wavefront modulation of Rayleigh surface waves by mechanically reconfigurable elastic metasurface

The expression of the generalized Snell's law for modulating the Rayleigh surface wave was derived. Based on the generalized Snell's law and the reconfigurability of the screw-and-nut structure, a reconfigurable elastic metasurface was proposed to modulate the wavefront of the Rayleigh surface wave. Flexible switching between different frequencies and functions, such as abnormal refraction, point focusing, beam focusing and self-bending beam can be realized just by adjusting the screw-in depths of the nuts. The flexibility and effectiveness of the reconfigurable metasurface were verified by numerical simulations. The study in this paper is expected to have a guiding significance for the design of new surface wave devices, and at the same time provides a new idea for modulation of seismic waves.

Flexible all-optical terahertz switch based on electromagnetically induced transparent-like metamaterial

The electromagnetically induced transparent-like metamaterials have received much attention because of their excellent slow-light properties and strong nonlinear effects. They have many promising applications in novel terahertz functional devices, high-sensitivity sensors, and optical storages. In this paper, a flexible terahertz switching device based on the electromagnetically induced transparent-like effect was proposed. The device exhibited a significant slow light phenomenon without pumped laser. Meanwhile, it is demonstrated that the device has a large modulation depth and excellent tunable slow light performance with low-power pumped laser. Its amplitude modulation depth can reach 60.4% and the group delay modulation can reach 32.5 ps. And the minimum group velocity of the device in slow terahertz light can reach 0.69 × 105 m/s. Moreover, the flexible substrate of the proposed device is not easily damaged. It makes the device suited for more complex environments well. Therefore, the device will have great potential for future research on high-performance terahertz switching devices.

Strain-induced degradation and recovery of flexible NbOx-based threshold switching device

We investigate the functionality of NbOx-based selector devices on a flexible substrate. It was observed that the failure mechanism of cyclic tensile strain is from the disruption of atom arrangements, which essentially led to the crack formation of the film. When under cyclic compressive strain, buckling delamination of the film occurs as the compressed films have debonded from their neighboring layers. By implementing an annealing process after the strain-induced degradation, recovery of the device is observed with reduced threshold and hold voltages. The physical mechanism of the device is investigated through Poole–Frenkel mechanism fitting, which provides insights into the switching behavior after mechanical strain and annealing process. The result demonstrates the potential of the NbOx device in flexible electronics applications with a high endurance of up to 105 cycles of cyclic bending strain and the recovery of the device after degradation.

Enhanced Exponential Stability Analysis for Switched Linear Time-Varying Delay Systems Under Admissible Edge-Dependent Average Dwell-Time Strategy

This article focuses on the exponential stability analysis for the switched linear systems with time-varying delay. By constructing a new augmented multiple Lyapunov–Krasovskii functional, containing time-varying delay information, coupling of current and delayed states, state integral, and state derivative terms the feasibility of the stability condition is considerably enhanced. Besides, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$</tex-math> </inline-formula> -order canonical Bessel–Legendre integral inequality and the convex function property are utilized to give more relaxed criteria. On the other hand, for the first time, more flexible switching is employed with an admissible edge-dependent average dwell-time strategy for the switched time-varying delay systems (STDSs). Novel improved delay-dependent stability conditions are expressed by two theorems in the form of linear matrix inequalities which can be used to guarantee the exponential stability of the STDSs in the different delay conditions. Finally, significant improvements over the state-of-the-art in terms of delay upper bound, exponential decay rate, and dwell time are presented by simulating two numerical examples and one practical example including streams water quality preserving.

Dual-band electro-optically steerable antenna

The ability to obtain dynamic control over an antenna radiation pattern is one of the main functions, desired in a vast range of applications, including wireless communications, radars, and many others. Widely used approaches include mechanical scanning with antenna apertures and phase switching in arrays. Both of those realizations have severe limitations, related to scanning speeds and implementation costs. Here we demonstrate a solution, where the antenna pattern is switched with optical signals. The system encompasses an active element, surrounded by a set of cylindrically arranged passive dipolar directors, functionalized with tunable impedances. The control circuit is realized as a bipolar transistor, driven by a photodiode. Light illumination in this case serves as a trigger, capable of either closing or opening the transistor, switching the impedance between two values. Following this approach, a compact half-a-wavelength footprint antenna, capable of switching between 6 dBi directional patterns within a few milliseconds’ latency was demonstrated. The developed light activation approach allows constructing devices with multiple almost non-interacting degrees of freedom, as a branched feeding network is not required. The capability of flexible switching between multiple electromagnetic degrees of freedom opens pathways to new wireless applications, where fast beam steering and beamforming performances are required.