Electrical Feedback Research Articles

Self-Adhesive Electronic Skin with Bio-Inspired 3D Architecture for Mechanical Stimuli Monitoring and Human-Machine Interactions.

Recent development of wearable devices is revolutionizing the way of artificial electronic skins (E-skin), physiological health monitoring and human-machine interactions (HMI). However, challenge remains to fit flexible electronic devices to the human skin with conformal deformation and identifiable electrical feedback according to the mechanical stimuli. Herein, an adhesive E-skin is developed that can firmly attach on the human skin for mechanical stimuli perception. The laser-induced adhesive layer serves as the essential component to ensure the conformal attachment of E-skin on curved surface, which ensures the accurate conversion from mechanical deformation to precise electrical readouts. Especially, the 3D architecture facilitates the non-overlapping outputs that bi-directional joint bending and distinguishes strain/pressure. The optimized E-skin with bio-inspired micro-cilia exhibited significantly improved sensing performances with sensitivity of 0.652 kPa-1 in 0-4kPa and gauge factor of 8.13 for strain (0-15%) with robustness. Furthermore, the adhesive E-skin can distinguish inward/outward joint bending in non-overlapping behaviors, allowing the establishment of ternary system to expand communication capacity for logic outputs such as effective Morse code and intelligent control. It expects that the adhesive E-skin can serve as a functional bridge between human and electrical terminals for applications from daily mechanical monitoring to efficient HMI.

Who engages in electricity conservation and to what effect after real-world, high-resolution feedback? An empirical analysis of Korean households with smart meters

Engagement with households to fully realize the potential of demand-side solutions has attracted policy attention. The potential of feedback has been understudied, especially regarding who engages more in electricity conservation. Furthermore, most studies have been limited to the Western context, with only a few that explore Asia. This study fills these gaps by investigating changes in household hourly electricity consumption patterns after its members receive high-resolution feedback. After data balancing, we partitioned 63 households into distinct groups using K-means clustering and investigated consumption changes after the provision of high-resolution electricity feedback through a mobile application. The results indicate mixed effectiveness of feedback: some households reduced consumption by about 13 %, while others increased it between 7 % and 20 %. In addition, statistical analysis using survey responses revealed that households with greater awareness of electricity costs and a stronger interest in climate change were more receptive to feedback. Demographic and housing attributes such as age, building type, and floor count also influenced the feedback effect. The findings recommend enhancing awareness of electricity costs and climate change and developing a better understanding of individuals’ challenges with changing conservation behaviors based on their demographic and housing characteristics.

SCARY ECG IN TAKOTSUBO CARDIOMYOPATHY

Abstract Takotsubo cardiomyopathy (TTC) is characterized by a transient ventricular wall motion abnormality and shares common features with acute coronary syndrome (ACS) with a wide spectrum of triggers, such as both emotional or physical, activating common toxic catecholamines–mediated pathways. TTC might be associated with severe clinical complications. We report a case of a 74–year female patient with circulatory shock with mixed phenotype, distributive due to sepsis and cardiogenic due to TTC. The patient presented to the emergency department with severe hypotension, pathological qSOFA score and clinical and laboratory findings consistent with severe sepsis. ECG showed diffuse lambda ST–segment elevation, also called “shark fin”(fig.1). According to hemodynamically unstable scenario and ECG pattern, emergency coronary angiography was performed, showing absence of coronary artery disease(fig. 2). Echocardiography revealed severe LV systolic disfunction (EF 20–25%) with apical ballooning and severe systolic anterior motion (SAM) of the anterior mitral leaflet eliciting dynamic LVOTO with peak gradient greater than 90 mmHg; fig. 3) and severe MR. Patient was treated with cautious fluid administration, hemotrasfusion and empiric large spectrum antibiotic therapy. According to TTC working diagnosis, even if septic state was thought to contribute to cardiogenic shock, norepinephrine was not administered due to concerns for LVOTO and SAM. After overcoming of dramatic first phase and after hemodynamic steadiness was achieved, beta blockade and ACEi were progressively administered. Seriate transthoracic echocardiogram revealed progressive improvement of LV systolic function, regression of apical ballooning, SAM and LVOTO. ECG monitoring showed regression of ischemic ST elevation. ST elevation has been described in about 56% of TTC cases, however with amplitude tipically lower than in STEMI. Lambda–wave ST elevation has been rarely reported. Vasospasm, local intermittent microvascular constriction, catecholamine–induced metabolic toxicity, transmural systolic wall tension and its the mechano–electric feedback can explain scaring ECG–pattern. Despite its rare prevalence in TTC “shark fin” pattern appears to relate to adverse outcome and it should be used as an early marker of potential further clinical deterioration, suggesting more intensive monitoring to avoid delays in possible therapy escalation.

Feasibility of Energy Self-Sufficiency by Biomass Production in A Brazilian State

Objective: This study aims to analyze the potential of using industrial black liquor or black lye residue from the eucalyptus pulp and paper production process as an alternative source of energy, in order to alleviate the current energy crisis. Theoretical framework: The study is based on literature regarding energy generation from biomass, focusing on the utilization of black liquor residue in thermoelectric power generation. Therefore, the thermoelectric generation from black liquor or black lye, cellulose biomass residue as an alternative source in energy generation, characterizes an important electrical feedback path in pulp production processes, also generating surplus energy for the supply network, relief of demand in the face of the current energy crisis. Method: The methodology employed in this study entails applied research, that investigates energy generation from black liquor in integrated plants of eucalyptus forest biomass, in reforestation areas for pulp production. Results and conclusion: The results indicate that energy generation from black liquor is a viable alternative to mitigate the current energy crisis, contributing to regional sustainable development. Projections suggest that by 2024, 85% of bioenergy can will be generated from this source in in the micro-region of Brazil. Therefore, adequate planning brings great expectations for regional sustainable development. Implications of the research: The research contributes to advancing scientific knowledge in the field of energy generation from biomass, demonstrating the potential of black liquor residue as an alternative energy source. Originality/value: The research contributes to advancing scientific knowledge in the field of energy generation from biomass, demonstrating the potential of black liquor residue as an alternative energy source.

Electrical feedback system for enhancing the RF power of photodetector.

In this paper, we propose a system for enhancing the RF output power of the photodetector, especially the power of fundamental tune and second-order harmonic, by feeding back part of the RF signal through an electrical feedback circuit. As a result of bias modulation and opto-electric mixing, the RF output power can be effectively enhanced. The structure of uni-traveling carrier photodetector (UTC-PD) is employed in this work. With the RF enhancement system, the power of fundamental tune and second-order harmonic improve by 6.4 dB and 9.9 dB respectively, under the condition of 26 dBm input optical power, 3 V bias voltage, and 14 GHz input optical signal. Further, it was observed that third-order harmonic appeared under the influence of this system.

Virtual Hall sensor triggered multi-MHz endoscopic OCT imaging for stable real-time visualization.

Circumferential scanning in endoscopic imaging is crucial across various disciplines, and optical coherence tomography (OCT) is often the preferred choice due to its high-speed, high-resolution, and micron-scale imaging capabilities. Moreover, real-time and high-speed 3D endoscopy is a pivotal technology for medical screening and precise surgical guidance, among other applications. However, challenges such as image jitter and non-uniform rotational distortion (NURD) are persistent obstacles that hinder real-time visualization during high-speed OCT procedures. To address this issue, we developed an innovative, low-cost endoscope that employs a brushless DC motor for scanning, and a sensorless technique for triggering and synchronizing OCT imaging with the scanning motor. This sensorless approach uses the motor's electrical feedback (back electromotive force, BEMF) as a virtual Hall sensor to initiate OCT image acquisition and synchronize it with a Fourier Domain Mode-Locked (FDML)-based Megahertz OCT system. Notably, the implementation of BEMF-triggered OCT has led to a substantial reduction in image jitter and NURD (<4 mrad), thereby opening up a new window for real-time visualization capabilities. This approach suggests potential benefits across various applications, aiming to provide a more accurate, deployable, and cost-effective solution. Subsequent studies can explore the adaptability of this system to specific clinical scenarios and its performance under practical endoscopic conditions.

Thermally programmable time delay switches for multi-step assays in paper-based microfluidics

Paper-based microfluidic devices offer advantages such as low cost and disposability for point-of-care diagnostic applications. However, actuation of fluids on paper can be a challenge in multi-step and complex assays. In this work, a thermally programmable time-delay switch (TPTDS) is presented which operates by causing delays in the fluid path of a microfluidics paper-based analytical device (μPAD) by utilizing screen-printed wax micro-bridges. The time-delay is achieved through an electrical power feedback loop which indirectly adjusts the temperature of each individual micro-bridge, melting the wax into the paper. The melted wax manipulates the fluid flow depending on its penetration depth into the paper channel, which is a function of the applied temperature. To demonstrate functionality of the proposed method, the TPTDS is employed to automate and perform the nitrate assay which requires sequential delivery of reagents. Colorimetric detection is used to quantify the results by utilizing an electronic color sensor.

Emerging interactively stretchable electronics with optical and electrical dual-signal feedbacks based on structural color materials

Emerging interactively stretchable electronics with optical and electrical dual-signal feedbacks based on structural color materials

Characterization of 2D Electrical Feedback Flow Control Valve

We proposed a novel 2D electric feedback flow control valve to solve the problem of low integration and control accuracy of flow control valves. The torque motor of the valve drives the 2D piston to rotate, and the rotational motion is converted to axial motion and drives the spool. The differential pressure feedback rod on the valve body can accurately measure the differential pressure of the oil inlet and outlet and cooperate with the spool displacement to form a closed loop of flow. This loop of flow then overcomes the influence of the valve port’s load change on the flow. We first established the mathematical model of the valve, obtained the transfer function, and performed the stability analysis. Then, we used AMESim as a platform for simulation analysis. Finally, we conducted the experimental verification of the valve. The verification showed the following characteristics of the valve. The hysteresis loop is 4.4%. The linearity is 1.6%. The response time is about 44 ms. The amplitude bandwidth is about 17 Hz. The phase bandwidth is about 28 Hz. The valve’s steady-state flow error is less than 8%, suggesting its broad application prospect in the aerospace and military fields.

Model predictive power control of a heat pipe cooled reactor

Heat pipe cooled reactor (HPR) has broad application prospects in deep space exploration, deep-sea submarine exploration, and other scenarios due to the small size, high inherent safety, and easy modularization and expansion. However, the HPR conducts thermal energy through evaporation and condensation of the working fluid inside the heat pipe. This feature makes the HPR a large time-delay system. If the power control system adopts the conventional PID algorithm, there will be a long settling time. Therefore, the model predictive control algorithm is proposed for the power control system to improve the control performance. The HPR linear model, which is developed by linearization of its nonlinear model, is chosen as the predictive model. The optimal control value is obtained by solving the optimization problem based on the predictive model and the electric power feedback value. The discrepancy between the predive model and the actual system response results in the presence of steady-state error. To solve this problem, an integral controller is added to eliminate the error. The appropriate control system parameters are tuned by the trial and error method. The proposed control system has satisfactory control performance, which can significantly shorten the settling time. The model predictive control can effectively overcome the influence of the large time-delay characteristic.

Preparation and characterization of conductive and stretchable MXene-based nanocomposite hydrogels initiated by metal ions

Conductive hydrogels are emerging as an advanced electronic platform for wearable sensors by synergizing the advantageous features of conductivity and flexibility. Especially conductive polymer hydrogels have widespread applications in the fields of catalysis, biomedicine, monitoring, and wearable electronic skin owing to the outstanding strain sensitivity and resilience thereof. Nevertheless, how to maintain the conductivity of hydrogels and electronic skins under strain or deformation remains a significant challenge. To tackle the said bottleneck, a multiple H-bonding MXene-based conductive hydrogel was established in the present study. With the participation of MXene and Fe[Formula: see text] ions, the hydrogel network was strengthened, which might be attributed to the H-bonding among the polymer chain, MXene, and Fe[Formula: see text] ions. Meanwhile, the elongation at break and compression modulus of Poly(vinyl alcohol) (PVA)- M3F hydrogels increased to 513% and 85.6[Formula: see text]kPa compared with the initial PVA hydrogel, respectively. After incorporating Fe[Formula: see text] ions, the PVA-M3F hydrogels exhibited greater conductivity, which was [Formula: see text][Formula: see text]S/cm. Notably, the PVA-M3F hydrogels displayed good resilience, leading to stable conductivity and strain sensitivity. Subsequently, a finger joint was designed to verify the maintenance of conductivity and monitoring behaviors. PVA-M3F conductive hydrogel was found to possess an outstanding capability for electrical signals feedback and was expected to be applied to electronic sensors or monitors. In summary, the introduction of MXene and Fe[Formula: see text] ions into PVA hydrogels can not only tune the conductivity but also have promising prospects as a countermeasure for wearable electronics.

Oil-gated isoporous membrane with micro-apertures for controllable pressure-induced passive flow regulator.

The pressure-driven liquid flow controller is one of the key components in diverse applications including microfluidic systems, biomedical drug injection devices, and pressurized water supply systems. Electric feedback loop based flow controllers are fine-tunable but expensive and complex. The conventional safety valves based on spring force are simple and low cost, but their diverse application is limited due to their fixed pressure range, size, and shape. Herein, we propose a simple and controllable liquid-flowing system combining a closed liquid reservoir and an oil-gated isoporous membrane (OGIM). The ultra-thin and flexible OGIM acts as an immediately responsive and precisely controlled gas valve to maintain internal pneumatic pressure as designed to induce constant liquid flow. The oil filling apertures act as a gate for gas flow depending on the applied pressure and the threshold (gating) pressure of the gate is determined by the surface tension of the oil and the gate diameter. It is confirmed that the gating pressure is precisely controlled by varying the gate diameter, which agrees with the theoretically estimated pressures. Based on stably maintained pressure due to the function of OGIM, the constant liquid flow rate is achieved even with the high gas flow rate.

Analysis of the Nonlinearities of an Axial Piston Pump of an Automatic Control System With Electric Feedback for a Two-Link Tracked Vehicle

Analysis of the Nonlinearities of an Axial Piston Pump of an Automatic Control System With Electric Feedback for a Two-Link Tracked Vehicle

A Sunflower‐Inspired Sun‐Tracking System Directed by an Ionic Liquid Photodetector

AbstractSunflower‐inspired sun‐tracking systems have been arousing intensive investigations owing to their benefits to improve the efficiency of solar energy collection. Photodetector based on photosensitive semiconductors is a mainstream choice in the sun‐tracking system, which directs solar collectors always facing the sun. However, photosensitive semiconductors to date have usually hidden the disadvantages of environmental pollution after disposal. As for these problems, this work develops a green ionic liquid‐based photodetector, which displays reliable electrical feedback in response to sunlight. This liquid sunlight detector can be readily recycled with less laborious and costly operations. It obeys a light sensing mechanism of photothermal conversion, so it does not involve the problems related to dark current and light saturation. As a practical demonstration, the ionic liquid‐based photodetector is assembled into a sun‐tracking system, which successfully pursues the moving sun in a real time. When such a sun‐tracking system is in tandem with optical fiber concentrator, sunlight can be efficiently collected and transported to desired position.

Electrically stimulated droplet injector for reduced sample consumption in serial crystallography

With advances in X-ray free-electron lasers (XFELs), serial femtosecond crystallography (SFX) has enabled the static and dynamic structure determination for challenging proteins such as membrane protein complexes. In SFX with XFELs, the crystals are typically destroyed after interacting with a single XFEL pulse. Therefore, thousands of new crystals must be sequentially introduced into the X-ray beam to collect full data sets. Because of the serial nature of any SFX experiment, up to 99% of the sample delivered to the X-ray beam during its “off-time” between X-ray pulses is wasted due to the intrinsic pulsed nature of all current XFELs. To solve this major problem of large and often limiting sample consumption, we report on improvements of a revolutionary sample-saving method that is compatible with all current XFELs. We previously reported 3D-printed injection devices coupled with gas dynamic virtual nozzles (GDVNs) capable of generating samples containing droplets segmented by an immiscible oil phase for jetting crystal-laden droplets into the path of an XFEL. Here, we have further improved the device design by including metal electrodes inducing electrowetting effects for improved control over droplet generation frequency to stimulate the droplet release to matching the XFEL repetition rate by employing an electrical feedback mechanism. We report the improvements in this electrically triggered segmented flow approach for sample conservation in comparison with a continuous GDVN injection using the microcrystals of lysozyme and 3-deoxy-D-manno-octulosonate 8-phosphate synthase and report the segmented flow approach for sample injection applied at the Macromolecular Femtosecond Crystallography instrument at the Linear Coherent Light Source for the first time.

Photonic vitrimer-based electronics with self-healing and ultrastable visual-digital outputs for wireless strain sensing

Flexible and stretchable electronics with mechanosensory functionality are highly desirable on account of their intriguing applications in smart wearable devices. Unfortunately, the susceptibility to structural damage and single electrical signal output restrict their further practical uses. Here, novel photonic vitrimer-based electronics (PVBEs) with self-healability and ultrastable visual-digital outputs are developed by harnessing vitrimer-induced structural evolutions of both photonic crystal (PC) and piezoresistive carbon textile. They demonstrate excellent strain sensing performances including synchronous electrical/optical response (0.25 s), high sensitivity (gauge factor, GF = 10.3), superior durability (>10000 cycles) and mechanochromism. Notably, dynamic covalent networks within vitrimer endow them self-healing ability of optical function, while the electromechanical performances are stably maintained benefiting from unique fully-embedded structure. Based on these merits, a new type of PVBE is demonstrated by incorporating wireless transmission system. Such a device can function as wirelessly visualized sensor for real-time tracking both large and subtle human movements with optical and electrical dual-signal feedbacks, realizing remote and precise visual-digital outputs. This work offers a versatile platform for emerging self-healing functional devices and visually interactive electronics, bringing huge developments in the era of the Internet of Things.

Low-Noise Frequency and Phase Locking of Yb-Doped Fiber Ring Cavity via Cavity Modulation

The control bandwidth of the injection-locked system utilizing a DFB fiber laser and fiber ring cavity is analyzed to estimate system stability. Within the bandwidth of the injection lock, an electrical feedback control loop is adopted to better suppress the phase noise of the fiber ring cavity. The entire system operates in low noise conditions of lower than −60 dBc/Hz from 1 Hz to 100 kHz. The output power of the fiber ring cavity is amplified stably to 0.346 W with a polarization extinction ratio of 31 dB based on an all-polarization-maintaining ring structure. The output laser from the single-mode fiber has the near diffraction-limited beam quality for wide applications.

Ultra-Stable Fiber Laser Based on Intracavity Dual Mode Self-Reference Mechanism

Ultra-stable lasers serve as the backbone for the most advanced optical metrology scientific experiments, enabling the ability to laser interferometry or atomic spectroscopy at the highest levels of precision, thanks to the rapid development of laser wavelength stabilization techniques based on optical or electrical feedback from an external reference such as absorption line or optical cavity. With the increasing interest in making these scientific systems portable and applying it outside of the laboratory, it still remains an open question as to how to realize a laser source that can reach the high wavelength stabilization and still remain sufficiently compact and portable for field use. Here, we describe a wavelength stabilization fiber laser with intracavity reference mechanism, by utilizing the beat note of dual modes inside the laser cavity as the laser wavelength drift reference signal. A laser wavelength drift less than 5 kHz and ADEV 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−13</sup> level at integration time scales from 0.01s to 1000s is achieved, which is to-date the best results for the laser wavelength stabilization without the external frequency reference. The outcome of this work presents a new way to achieve an ultra-stable laser with a simpler, lower cost feature. It offers new insights to promote the highest precision optical metrology scientific application outside of the laboratory, and also gives the possibilities of applying the ultra-stable laser source into a wider range of industrial application.

Laser phase noise suppression and quadratures noise intercoupling in a mode cleaner

Suppression phase noise of a laser is a great practical significance in applications of phase-sensitive precision measurement. To suppress the phase noise, an ultra-stable cavity incorporating with an electrical feedback control loop is always the popular choice, in which the linewidth of the cavity should be narrower than that of the laser to provide a stable reference standard. Here, we experimentally verify that mode cleaner plays a noise suppression role for phase quadrature in the whole frequency range of the photoelectric detectors, even though its linewidth is 103 larger than the laser one. Meanwhile, we found that the noise suppression for one quadrature is codetermined by the noise of the two quadratures of the input field. Our demonstration provides a new and in-depth interpretation for phase noise suppression in a mode cleaner with larger linewidth than the laser one that is important in phase-sensitive sensing application.

Electrical activities, excitability and multistability transitions of the hybrid neuronal model induced by electromagnetic induction and autapse

Electromagnetic induction and autapse play important roles in regulating the electric activities, excitability, and bistable structure of neurons. The firing activities and global bifurcation patterns of a four-dimensional (4D) hybrid neuron model that combines the fast dynamic variables of the Wilson model and the slow feedback variables of the Hindmarsh–Rose (HR) model and magnetic flux are investigated based on the Matcont software and numerical calculation. The effect of electrical autapse on the dynamic evolution of the system is also discussed emphatically. Upon encountering electromagnetic induction, the hybrid neuron model exhibits complex global stability, Hopf bifurcation, and saddle-node bifurcation. Intriguingly, the system presents initial sensitivity and a bistable structure consisting of quiescent and period-1 spiking near the Hopf bifurcation point. It is worth noting that the feedback type of electrical autapse, including positive and negative feedback, has completely different effects on this bistable structure. Notably, the negative feedback autapse can expand and change the bistable region, so that the system generates a new bistable structure consisting of quiescent and periodic bursting states, and its bursting activities are also promoted. Moreover, extensive numerical results show that the system generally maintains a comb-shaped chaotic structure, abundant bifurcation patterns, and multistability. It should be noted that electrical autapse feedback types and time delays do not change the regular bifurcation structures but operate a complex regulatory mechanism for the coexistence of multiple attractors. These results will provide useful insights into the neuron’s dynamics under the atmosphere of electromagnetic induction and also electrical autapse.