Voltage Sensitivity Research Articles

Sensing Characteristics of SARS-CoV-2 Spike Protein Using Aptamer-Functionalized Si-Based Electrolyte-Gated Field-Effect Transistor (EGT).

The sensing responses of SARS-CoV-2 spike protein using top-down-fabricated Si-based electrolyte-gated transistors (EGTs) have been investigated. An aptamer was employed as a receptor for the SARS-CoV-2 spike protein. The EGT demonstrated excellent intrinsic characteristics and higher sensitivity in the subthreshold regime compared to the linear regime. The limit of detection (LOD) was achieved as low as 0.94 pg/mL and 20 pg/mL for the current and voltage sensitivity, respectively. To analyze the sensing responses of EGT in detecting the aptamer-SARS-CoV-2 spike protein conjugate, a lumped-capacitive model with the presence of an effective dipole potential and an effective capacitance of the functionalized layer component was employed. The aptamer-functionalized EGT showed high sensitivity even in 10 mM phosphate-buffered saline (PBS) solution. These results suggest that Si-based EGTs are a highly promising method for detecting SARS-CoV-2 spike proteins.

Multi-objective optimization based demand response program with network aware peer-to-peer energy sharing

Demand-side energy management programs, such as Demand Response (DR) and Peer-to-Peer (P2P) energy sharing, have recently begun to be implemented to optimize the integration of distributed clean energy resources and to leverage generation and demand-side flexibility in the distribution system. In general, if not optimally planned, P2P energy sharing may have a negative impact on power distribution utilities’ primary objectives, such as minimizing energy losses, flattening the load profile, and improving voltage regulation. The DR program is considered as one of the potential mechanisms to alleviate the possible adverse impact of P2P energy sharing while maintaining the interest of peers participating in decentralized energy sharing. The analysis of the impact of P2P energy sharing with varying peers’ physical locations involved utilizing the Voltage Sensitivity Factor (VSF). The influence on the distribution network is contingent upon the difference in VSF values among the individual peers engaged in energy sharing. This study introduced the k-Means algorithm for VSF-based peer clustering, thereby generating the merit order and realizing the network-aware P2P energy transactions for the selected scenarios. A multi-objective optimization model-based real-time pricing-based DR scheme has been formulated to address the adverse impact of P2P energy sharing. Furthermore, this study quantifies the impact of DR potentials, which vary from 5% to 45% in increments of 10%, on the Peak-to-Average Ratio (PAR), overall energy loss, and total energy cost reduction. The modified IEEE 33 bus system incorporating industrial, commercial, and residential consumers’ load profile of 24 h at selected buses has been considered to test and validate the proposition.

High resolution and large measurement range voltage sensing based on an optoelectronic oscillator utilizing an unbalanced Mach-Zehnder interferometer.

A voltage sensor with high resolution and large measurement range based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The key component in the cavity to select the oscillating signal is a finite impulse response (FIR)-microwave photonic filter (MPF) which consists of a sinusoidal broadband optical signal, an unbalanced Mach-Zehnder interferometer (MZI), a section of dispersion compensating fiber, and a photodetector. The center frequency of the FIR-MPF is mainly determined by the free spectral range (FSR) of the FIR-MPF. In the lower arm of the MZI, a cylindrical piezoelectric ceramic (PZT) wrapped with a section of optical fiber acts as voltage sensing head. Due to the inverse piezoelectric effect of PZT, the variation of the voltage will cause radial deformation of the cylindrical PZT and then lead to the change of the FSR of the MZI, determining the shift of center frequency of FIR-MPF as well as the frequency of the oscillating signal of the OEO. Thus, by monitoring the shift of the oscillation frequency of the OEO using an electric spectrum analyzer or a digital signal processor, a high-speed interrogation and high-resolution voltage measurement can be realized. Additionally, in the proposed scheme, an infinite impulse response (IIR)-MPF consisting of a fiber ring resonator is cascaded with the FIR-MPF to ensure the single-mode oscillation of the OEO. The experimental results show that a total range of 1700 V voltage sensing from - 200 V to 1500 V is accomplished with the voltage sensitivity of 0.25 GHz/100 V and the resolution of 0.3 V. By adjusting the proportion of the length of single mode fiber between two branches of MZI, the impact of temperature can be greatly reduced. The proposed sensor offers advantages such as a large measurement range, high resolution, high-speed interrogation, and stability to temperature disturbances, making it highly suitable for sensing applications in smart grids.

Differential pressure sensors based on transfer-free piezoresistive layered PdSe2 thin films

Piezoresistive layered two-dimensional (2D) crystals offer intriguing promise as pressure sensors for microelectromechanical systems (MEMS) due to their remarkable strain-induced conductivity modulation. However, integration of the conventional chemical vapor deposition grown 2D thin films onto a micromachined silicon platform requires a complex transfer process, which degrades their strain-sensing performance. In this study, we present a differential pressure sensor built on a transfer-free piezoresistive PdSe2 polycrystalline film deposited on a SiN x membrane by plasma-enhanced selenization of a metal film at a temperature as low as 200 °C. Based on the resistance change and finite element strain analysis of the film under membrane deflection, we show that a 7.9 nm thick PdSe2 film has a gauge factor (GF) of −43.3, which is ten times larger than that of polycrystalline silicon. The large GF enables the development of a diaphragm pressure sensor with a high sensitivity of 3.9 × 10−4 kPa−1 within the differential pressure range of 0–60 kPa. In addition, the sensor with a Wheatstone bridge circuit achieves a high voltage sensitivity of 1.04 mV·kPa−1, a rapid response time of less than 97 ms, and small output voltage variation of 8.1 mV in the temperature range of 25 °C to 55 °C. This transfer-free and low-temperature grown PdSe2 piezoresistive thin film is promising for MEMS transducer devices.

Voltage tunes mGlu5 receptor function, impacting synaptic transmission.

Voltage sensitivity is a common feature of many membrane proteins, including some G-protein coupled receptors (GPCRs). However, the functional consequences of voltage sensitivity in GPCRs are not well understood. In this study, we investigated the voltage sensitivity of the post-synaptic metabotropic glutamate receptor mGlu5 and its impact on synaptic transmission. Using biosensors and electrophysiological recordings in non-excitable HEK293T cells or neurons. We found that mGlu5 receptor function is optimal at resting membrane potentials. We observed that membrane depolarization significantly reduced mGlu5 receptor activation, Gq-PLC/PKC stimulation, Ca2+ release and mGlu5 receptor-gated currents through transient receptor potential canonical, TRPC6, channels or glutamate ionotropic NMDA receptors. Notably, we report a previously unknown activity of the NMDA receptor at the resting potential of neurons, enabled by mGlu5. Our findings suggest that mGlu5 receptor activity is directly regulated by membrane voltage which may have a significant impact on synaptic processes and pathophysiological functions.

Microfabrication of piezoelectric MEMS based on thick LiNbO3 single-crystal films

Microfabrication procedure of piezoelectric micro electro-mechanical systems based on 5 μm thick LiNbO3 films on SiO2/Si substrate at wafer scale including deep dry etching of thick LiNbO3 films by implementing pulsed mode of Ar/SF6 gas was developed. In particular, two (YXlt)/128°/90°LiNbO3-Si cantilevers with tip mass were fabricated and characterized in terms of resonance frequency (511 and 817 Hz), actuation and acceleration sensing capabilities. The quality factor of 89.5 and the electromechanical coupling of 4.8% were estimated from measured frequency dependency of electrical impedance, fitted by using Butterworth–Van Dyke model. The fabricated piezoelectric micro-electro-mechanical systems have demonstrated highly linear displacement with good sensitivity (5.28 ± 0.02 μm V−1) as a function of applied voltage and high sensitivity to vibrations of 667 mV g−1 indicating a suitability of the structure for actuation purposes and for acceleration or frequency sensing with high precision, respectively.

Innovative Test Bench for RF and High-Voltage Component Characterization for MRI Applications: A Comprehensive Review

This scientific paper presents a detailed exploration of the electrical characterization of commercially available trimmers, conducted in collaboration with Siemens Medical. The study encompasses the establishment of a specialized measurement bench for impulse mode electrical tests, involving the adaptation of the signal generator with an adjustable supercapacitor and variable inductance. For precise measurements, a carefully designed filtering system prevents voltage overshoots. Given the critical sensitivity of voltage and frequency measurements for passive components in RF and high-voltage applications, the methodology is further refined to achieve optimal compromises across various parameters. The primary objective remains the determination of the voltage across the evaluated capacitor using the proportionality coefficient 𝛼, essential for accurate trimmer characterizations. In this paper, useful insights are provided into the electrical characterization of trimmers, as well as a refined methodology designed for RF and high-voltage applications. The findings presented herein enhance our understanding of trimmer behavior, offering potential implications for improved component selection and performance in a range of electrical systems.

S-palmitoylation of NaV1.7 voltage-gated sodium channels regulates their activity and voltage sensitivity

S-palmitoylation of NaV1.7 voltage-gated sodium channels regulates their activity and voltage sensitivity

Heterologous expression of the human wild-type and variant NaV 1.8 (A1073V) in rat sensory neurons.

Silent inflammatory bowel disease (IBD) is a condition in which individuals with the active disease experience minor to no pain. Voltage-gated Na+ (NaV ) channels expressed in sensory neurons play a major role in pain perception. Previously, we reported that a NaV 1.8 genetic polymorphism (A1073V, rs6795970) was more common in a cohort of silent IBD patients. The expression of this variant (1073V) in rat sympathetic neurons activated at more depolarized potentials when compared to the more common variant (1073A). In this study, we investigated whether expression of either NaV 1.8 variant in rat sensory neurons would exhibit different biophysical characteristics than previously observed in sympathetic neurons. Endogenous NaV 1.8 channels were first silenced in DRG neurons and then either 1073A or 1073V human NaV 1.8 cDNA constructs were transfected. NaV 1.8 currents were recorded with the whole-cell patch-clamp technique. The results indicate that 1073A and 1073V NaV 1.8 channels exhibited similar activation values. However, the slope factor (k) for activation determined for this same group of neurons decreased by 5 mV, suggesting an increase in voltage sensitivity. Comparison of inactivation parameters indicated that 1073V channels were shifted to more depolarized potentials than 1073A-expressing neurons, imparting a proexcitatory characteristic. These findings differ from previous observations in other expression models and underscore the challenges with heterologous expression systems. Therefore, the use of human sensory neurons derived from induced pluripotent stem cells may help address these inconsistencies and better determine the effect of the polymorphism present in IBD patients.

Distributed Voltage Security Enhancement Using Measurement-Based Voltage Sensitivities

The existing susceptance-based methods adopt the constant susceptance matrix as the voltage sensitivities and have been widely applied in voltage security enhancement of power systems. However, the existing methods may be inefficient under the heavy loading condition in which the fundamental of decoupled power flow fails to hold. In this case, the inaccurate voltage sensitivities in the existing method lead to the inefficient voltage security enhancement with more required iterations of the numerical convergence. In order to improve such deficiency, the distributed voltage security enhancement method using the measurement-based voltage sensitivities is proposed in this paper. By using real-time measurements of phasor measurement units (PMUs), the multi-port equivalent models of the power grid are built and used to derive the measurement-based voltage sensitivities and the system transmission capability sensitivities. By using the measurement-based sensitivities, the proposed method can be formulated as the measurement-based optimization problem and further implemented in the distributed framework through using alternating direction method of multipliers (ADMM). Simulations on IEEE 118-bus and IEEE 300-bus test systems are presented to validate the effectiveness of the proposed method.

Data-Driven Affinely Adjustable Robust Volt/VAr Control

Recent years have seen the increasing proliferation of distributed energy resources with intermittent power outputs, posing new challenges to the voltage management in distribution networks. To this end, this paper proposes a data-driven affinely adjustable robust Volt/VAr control (AARVVC) scheme, which modulates the smart inverter’s reactive power in an affine function of its active power, based on the voltage sensitivities with respect to real/reactive power injections. To achieve a fast and accurate estimation of voltage sensitivities, we propose a data-driven method based on deep neural network (DNN), together with a rule-based bus-selection process using the bidirectional search method. Our method only uses the operating statuses of selected buses as inputs to DNN, thus significantly improving the training efficiency and reducing information redundancy. Finally, a distributed consensus-based solution, based on the alternating direction method of multipliers (ADMM), for the AARVVC is applied to decide the inverter’s reactive power adjustment rule with respect to its active power. Only limited information exchange is required between each local agent and the central agent to obtain the slope of the reactive power adjustment rule, and there is no need for the central agent to solve any (sub)optimization problems. Numerical results on the modified IEEE-123 bus system validate the effectiveness and superiority of the proposed data-driven AARVVC method.

Electromagnetic Radiation Detector with a Wavelength Range of the 2 mm Based on the Schottky Barrier Diodes

The results of development and research of a 2-mm band detector based on a series pair of the Schottky barrier diodes (SBDs) are presented. The realised waveguide-microstrip design of the detector and the principle of operation are described. The linear calculation of the detector characteristics and the model of the nonlinear element based on the equivalent parameters of the SBDs in the operating mode are considered. The technique of measuring the characteristics of the 2-mm detector is specified. Experimental results of voltage sensitivity, current sensitivity, return loss of the detector input are given. The dependence of the voltage drop on the series pair of SBDs on the power of the EHF signal is investigated. The dependence of the voltage sensitivity and VSWR of the detector input on the bias current is also investigated. The influence of the equivalent parameters of the nonlinear element on the voltage sensitivity and VSWR of the detector input is considered.

Broadly tunable filter based on a graphene MEMS-photonic crystal composite structure and its application in single-pixel full-color displays

A graphene MEMS tunable narrowband filter with minimal deformation (<2 pm), high voltage sensitivity (>400 nm V−1), high tunable bandwidth (>200 nm) was proposed, achieving full-color display within a single pixel, color gamut reaching 214% of sRGB.

Localized structure in secondary distribution system voltage sensitivity matrices

Localized structure in secondary distribution system voltage sensitivity matrices

Development of a high-performance cymbal vector hydrophone

Detecting the direction of sound wave propagation using conventional acoustic hydrophones can be challenging, as they are omnidirectional and only measure the magnitude of sound pressure. However, vector hydrophones offer a solution to this problem, which enables the determination of both magnitude and direction of sound waves. In this study, we propose a novel structure for a vector hydrophone that consists of two cymbal transducers attached to a hollow cylindrical frame, positioned facing each other. Initially, we analyze the received voltage sensitivity of the two cymbal transducers and evaluate the suitability of the structure as a vector hydrophone by implementing a dipole mode beam pattern. Furthermore, we investigate the impact of structural parameters on the performance of the vector hydrophone. Based on these findings, we derive the optimal structure for the vector hydrophone, maximizing its sensitivity. Finally, we validate the design by manufacturing a prototype of the cymbal vector hydrophones and comparing their measured performance with the calculated values.

FACTS placement for reactive power planning with weak node constraints using an improved symbiotic search algorithm

In this paper, an economically feasible and reliable operation of the IEEE 57 bus system for Optimal Power Flow (OPF) is proposed. The Improved Symbiotic Organisms Search (ISOS) algorithm is proposed for effective reactive power planning as an OPF issue. Further, the optimal position of Flexible AC Transmission Systems (FACTS) is taken into consideration, by including the existing system controlling variables like reactive power generators output, transformer tapping and capacitors connected at shunt. The objective of the work is two-fold; i.e., to reduce the energy loss and to enhance the voltage profile within the prescribed limit by ensuring the economic operation and investment cost of FACTS in the system. In this work, two FACTS devices like Static Var Compensator (SVC) and Thyristor-Controlled Series Controller (TCSC) have been taken into consideration. Voltage sensitivity indicator and reactive power flow are two tools that are utilised in order to locate weak nodes for the implementation of FACTS. Finally, the performance of the ISOS algorithm is compared with that of three other state- of-the -art optimization techniques, such as, Symbiotic Organisms Search (SOS), Differential Evolution (DE) and Teaching Learning Based Optimization (TLBO). A Non-parametric statistical analysis is also performed to investigate the dominance of the ISOS algorithm over others.

Multilevel variable control for impulse-discharge thermochemical truing of diamond cutting edges in precision grinding

Precision grinding depends on the diamond cutting edges with good protrusion uniformity that are acquired by impulse-discharge thermochemical truing. However, the impulse-discharge thermal is unstable due to the uncertain discharge gap derived from irregularly changed grain top heights, leading to random diamond thermochemical removal. Under the uncertainty, a multilevel fuzzy-based control of kinematic and electrical variables is proposed to stabilize the impulse-discharge power during truing. The objective is to realize the cooperation of impulse-discharge, thermochemical and mechanical processes for diamond truing effect trace. First, the impulse-discharge signal was collected to acquire the transfer functions of impulse-discharge power. Then, an on-site experiment with small sample was processed to determine the discharge voltage sensitivities of kinematic and electrical variations. In order to improve the control performance, the control process with fuzzy logic was modeled to tune the output ratios of kinematic and electrical variations by particle swarm algorithm. Finally, the designed controller was experimentally applied to the impulse-discharge thermochemical truing, followed with dry plunge grinding of hardened steel. It is shown that the kinematic and electrical variables for the uncertainty compensation are linearly related to the spark-discharge voltage. Accordingly, the fuzzy-based control may be applied to the multilevel variable adjustment. The controller with tuned output ratios reaches small steady-state error, few trigger times and no overshoot to regulate the impulse-discharge power within 5 % error in actual truing. By integrating physical behavior and experiential knowledge rather than big data driving, the controllable impulse-discharge power for required diamond cutting edges advances the stable smooth surface grinding.

Negative Capacitance Dual-Gated ISFETs as Ultra-Sensitive pH Sensors.

Ion-sensitive field-effect transistors (ISFETs) are promising candidates for next-generation pH sensors, enabling highly sensitive and label-free biomolecular and chemical detection. Emerging FETs based on the negative capacitance (NC) effect offer steep-subthreshold switching and higher drive current simply by integrating a ferroelectric (FE) material into the gate stack. Here, we propose a novel NC dual-gated ISFET (NC-DG-ISFET)-based pH sensor, with FE layers integrated into both the top and the bottom gate stacks. The current and voltage sensitivities of the proposed device are extracted from its transfer characteristics, obtained by combining the numerical solutions of the one-dimensional (1D) Landau-Khalatnikov (L-K) equation with three-dimensional (3D) technology computer-aided design (TCAD) simulations. Results show that the NC-DG-ISFET can surpass the sensitivity of some of the state-of-the-art DG-ISFET pH sensors. The inclusion of the FE layers into the gate stacks of a baseline DG-ISFET leads to 51% reduction in subthreshold swing (SS), causing a 5× increase in current sensitivity (SI) in the subthreshold region of operation and a 2× increase in voltage sensitivity (SV). The influence of channel thickness and channel length on the sensor performance is also invesitgated. The findings presented here provide a new pathway to leverage the steep-switching behavior of NCFETs for the next generation of highly sensitive and label-free DG-ISFET pH sensors.

Layered porous Na0.5Bi0.5TiO3-0.06BaTiO3 for enhanced pyroelectric thermal energy harvesting

Layered Na0.5Bi0.5TiO3-0.06BaTiO3 (NBT-6BT) ceramics of dense-porous-dense structure along the thickness are fabricated. The porous layer is sandwiched between the top and bottom dense layer, nullifying the electrode material's seepage into pores. Thus, porous pyroelectric material reduces the dielectric breakdown during poling and increases the repeatability of the poling process. The burnt-out polymer technique creates 10.7 %, 14.23 %, 21.3 % and 28 % porosity. The dielectric constant in layered porous structure decreased from 785 to 221 as the porosity increased from 5.4 % (pure NBT-6BT) to 28 % (layered NBT-6BT-12) at room temperature (poled condition). The introduction of porosity showed an increment of 124 % in the modified pyroelectric energy harvesting figure of merit Fe* for NBT-6BT-12 at 80 °C. The real-time thermal energy harvesting obtained by heating and cooling the pyroelectric material demonstrated equivalent voltage for NBT-6BT-12 layered porous structure. The layered porous structure can be a viable alternative for enhanced voltage sensitivity and energy harvesting.

Folding of prestin's anion-binding site and the mechanism of outer hair cell electromotility.

Prestin responds to transmembrane voltage fluctuations by changing its cross-sectional area, a process underlying the electromotility of outer hair cells and cochlear amplification. Prestin belongs to the SLC26 family of anion transporters yet is the only member capable of displaying electromotility. Prestin's voltage-dependent conformational changes are driven by the putative displacement of residue R399 and a set of sparse charged residues within the transmembrane domain, following the binding of a Cl- anion at a conserved binding site formed by the amino termini of the TM3 and TM10 helices. However, a major conundrum arises as to how an anion that binds in proximity to a positive charge (R399), can promote the voltage sensitivity of prestin. Using hydrogen-deuterium exchange mass spectrometry, we find that prestin displays an unstable anion-binding site, where folding of the amino termini of TM3 and TM10 is coupled to Cl- binding. This event shortens the TM3-TM10 electrostatic gap, thereby connecting the two helices, resulting in reduced cross-sectional area. These folding events upon anion binding are absent in SLC26A9, a non-electromotile transporter closely related to prestin. Dynamics of prestin embedded in a lipid bilayer closely match that in detergent micelle, except for a destabilized lipid-facing helix TM6 that is critical to prestin's mechanical expansion. We observe helix fraying at prestin's anion-binding site but cooperative unfolding of multiple lipid-facing helices, features that may promote prestin's fast electromechanical rearrangements. These results highlight a novel role of the folding equilibrium of the anion-binding site, and help define prestin's unique voltage-sensing mechanism and electromotility.