mV Voltage Research Articles

Design and Implementation of a Resistive MV Voltage Divider

In this paper, a new resistive voltage divider having vertically placed resistors is designed. This resistive voltage divider is supposed to be utilized in laboratory medium voltage measurement in the frequency range from DC to 9 kHz where most of the voltage transducers are failed to accurately function. The simulation results, validated by measurements, show a frequency response where the scale factor and the phase error variation ranges are respectively 2 and 4 times better than the ones required by standard IEC 60044-8:2002. These results take advantage from a plate connected to the low voltage section and a shield separating the HV part from the LV arm of the voltage divider. The maximum scale factor deviation from the rated value is about 2.4% and the maximum phase error is about 22.9 mrad. These promising results have been obtained in a wide frequency range up to 9 kHz, which is quite unusual for resistive dividers.

Electronic characterization of Geobacter sulfurreducens pilins in self-assembled monolayers unmasks tunnelling and hopping conduction pathways.

The metal-reducing bacterium Geobacter sulfurreducens produces protein nanowires (pili) for fast discharge of respiratory electrons to extracellular electron acceptors such as iron oxides and uranium. Charge transport along the pili requires aromatic residues, which cluster once the peptide subunits (pilins) assemble keeping inter-aromic distances and geometries optimal for multistep hopping. The presence of intramolecular aromatic contacts and the predominantly α-helical conformation of the pilins has been proposed to contribute to charge transport and rectification. To test this, we self-assembled recombinant, thiolated pilins as a monolayer on gold electrodes and demonstrated their conductivity by conductive probe atomic force microscopy. The studies unmasked a crossover from exponential to weak distance dependence of conductivity and shifts in the mechanical properties of the film that are consistent with a transition from interchain tunneling in the upper, aromatic-free regions of the helices to intramolecular hopping via aromatic residues at the amino terminus. Furthermore, the mechanistic stratification effectively "doped" the pilins at the amino terminus, favoring electron flow in the direction opposite to the helix dipole. However, the effect of aromatic dopants on rectification is voltage-dependent and observed only at the low (100 mV) voltages that operate in biological systems. The results thus provide evidence for a peptide environment optimized for electron transfer at biological voltages and in the direction needed for the respiration of external electron acceptors. The implications of these results for the development of hybrid devices that harness the natural abilities of the pilins to bind and reduce metals are discussed.

MoS2 Nanoplatelet Arrays as a Support for Decoration with Pt Nanoparticles and its Effect on Electrochemical Water Splitting

MoS2 Nanoplatelet Arrays as a Support for Decoration with Pt Nanoparticles and its Effect on Electrochemical Water Splitting Developing an active electro catalyst for water splitting remains one of the key tasks for further progress of this technology. In this study, the surprising enhancement of HER performance was obtained at Ti substrate covered by few-layered nanoplatelet molybdenum sulphides/oxides mixture array fabricated via hydrothermal synthesis and subsequent electrochemical decoration with ultra-small Pt nanoparticles. By this way, the enhancement of HER efficiency up to 10 times and more was observed, achieving the performance of HER characteristic to Pt surface. To disclose the transformations carried out during prolonged and intensive hydrogen evolution at the constructed electrodes, scanning electron microscopy (SEM) and high resolution SEM (HRSEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and cyclic voltammetry investigations were performed. The results obtained were attributed to the creation of numerous extremely active catalytic sites along the nanoplatelet edges and on their surface throughout the desulfurization by a stream of evolved hydrogen and deposition of Pt/PtO nanoparticles. Surprising ultra-high catalytic efficiency of HER with an overpotential of few mV and current density exceeding 190 mA cm-2 at -200 mV vs RHE bias voltage was obtained using just 6.0 mg m-2 Pt loading.

Interplay among distinct Ca2+ conductances drives Ca2+ sparks/spontaneous transient outward currents in rat cerebral arteries.

Distinct Ca2+ channels work in a coordinated manner to grade Ca2+ spark/spontaneous transient outward currents (STOCs) in rat cerebral arteries. The relative contribution of each Ca2+ channel to Ca2+ spark/STOC production depends upon their biophysical properties and the resting membrane potential of smooth muscle. Na+ /Ca2+ exchanger, but not TRP channels, can also facilitate STOC production. Ca2+ sparks are generated in a voltage-dependent manner to initiate spontaneous transient outward currents (STOCs), events that moderate arterial constriction. In this study, we defined the mechanisms by which membrane depolarization increases Ca2+ sparks and subsequent STOC production. Using perforated patch clamp electrophysiology and rat cerebral arterial myocytes, we monitored STOCs in the presence and absence of agents that modulate Ca2+ entry. Beginning with CaV 3.2 channel inhibition, Ni2+ was shown to decrease STOC frequency in cells held at hyperpolarized (-40mV) but not depolarized (-20mV) voltages. In contrast, nifedipine, a CaV 1.2 inhibitor, markedly suppressed STOC frequency at -20mV but not -40mV. These findings aligned with the voltage-dependent profiles of L- and T-type Ca2+ channels. Furthermore, computational and experimental observations illustrated that Ca2+ spark production is intimately tied to the activity of both conductances. Intriguingly, this study observed residual STOC production at depolarized voltages that was independent of CaV 1.2 and CaV 3.2. This residual component was insensitive to TRPV4 channel modulation and was abolished by Na+ /Ca2+ exchanger blockade. In summary, our work highlights that the voltage-dependent triggering of Ca2+ sparks/STOCs is not tied to a single conductance but rather reflects an interplay among multiple Ca2+ permeable pores with distinct electrophysiological properties. This integrated orchestration enables smooth muscle to grade Ca2+ spark/STOC production and thus precisely tune negative electrical feedback.

A 1 A, Dual-Inductor 4-Output Buck Converter With 20 MHz/100 MHz Dual-Frequency Switching and Integrated Output Filters in 65 nm CMOS

The dual-frequency dual-inductor multiple-output (DF-DIMO) buck converter topology is presented. The topology employs a dual-phase 20 MHz current-mode-controlled input stage to reduce the inductance required per phase to only 200 nH, and a 4-output 100 MHz comparator-controlled fully integrated output stage to reduce the capacitance required per output to 10 nF. In order to enable each output to handle up to 250 mA load with less than 40 mV voltage ripple, a third-order bond-wire-based notch filter is employed at each output for voltage ripple suppression. Additionally, the proposed design employs dynamic output re-ordering to enhance cross-regulation performance, interleaved pulse-skipping to enhance light-load efficiency and dynamic performance, and high-gain error amplifier in the output feedback loop to enhance DC load regulation. Targeting multi-core DSPs, the proposed design is implemented in standard 65 nm CMOS technology with 1.8 V input, and outputs in the range of 0.6– 1.2 V with a total load of 1 A. It achieves a peak efficiency of 74%, less than 40 mV output voltage ripple, 0.5 V/70 ns dynamic voltage scaling (DVS), and settling time of less than 85 ns for 125 mA load steps; all with no observable cross-regulation transients.

Air breathing cathode-microbial fuel cell with separator based on ionic liquid applied to slaughterhouse wastewater treatment and bio-energy production

BACKGROUND The present work explores the catalytic and electric performance of a microbial fuel cell (MFC) implemented with high chemical oxygen demand (COD) industrial wastewater from Spain. The polymer inclusion membrane based on 70% [MTOA][Cl] IL was used as separator and showed a good efficiency in power production and COD removal. RESULTS Outputs of 72% in COD conversion, 200 mV voltage and 32 mW m−3 power density were obtained, demonstrating that slaughterhouse wastewater is a good feedstock for the scale-up of this technology. Furthermore, the effect of the microbial fuel cell on the physical/chemical parameters of the slaughterhouse wastewater was analyzed. The concentration of nitrite, orthophosphate, sulfate and ammonium was reduced by more than half. CONCLUSIONS Air breathing cathode-microbial fuel cells based on polymer ionic liquids inclusion membranes allow the treatment of an industrial and high load slaughterhouse wastewater with good depuration and electrical performance efficiency. © 2016 Society of Chemical Industry

Solar-Driven Reduction of 1 atm of CO2 to Formate at 10% Energy-Conversion Efficiency by Use of a TiO2-Protected III–V Tandem Photoanode in Conjunction with a Bipolar Membrane and a Pd/C Cathode

A solar-driven CO2 reduction (CO2R) cell was constructed, consisting of a tandem GaAs/InGaP/TiO2/Ni photoanode in 1.0 M KOH(aq) (pH = 13.7) to facilitate the oxygen-evolution reaction (OER), a Pd/C nanoparticle-coated Ti mesh cathode in 2.8 M KHCO3(aq) (pH = 8.0) to perform the CO2R reaction, and a bipolar membrane to allow for steady-state operation of the catholyte and anolyte at different bulk pH values. At the operational current density of 8.5 mA cm–2, in 2.8 M KHCO3(aq), the cathode exhibited 94% Faradaic efficiency for the reduction of 1 atm of CO2(g) to formate. The anode exhibited a 320 ± 7 mV overpotential for the OER in 1.0 M KOH(aq), and the bipolar membrane exhibited ∼480 mV voltage loss with minimal product crossovers and >90 and >95% selectivity for protons and hydroxide ions, respectively. The bipolar membrane facilitated coupling between two electrodes and electrolytes, one for the CO2R reaction and one for the OER, that typically operate at mutually different p...

Operation of a Medium Voltage Distribution Network with a Large Penetration of Distributed Generation

The paper presents the study of the behaviour of a real MV public distribution network in a mid-size in Italy, characterized by a very large amount of distributed generation (DG), reaching 100% of supplied network load. A parametric steady-state analysis of operating regimes was carried out, considering different load and DG scenarios (maximum and minimum load, maximum and minimum DG). The deterministic study did not evidence any operational problem, such as overloads and violation of voltage constraints. Occasional voltage violations (high MV voltages at full DG output) are easily overcome by tap-changer operation on the HV/MV transformers. Although feeder voltage profiles are actually improved by DG, a drastic power factor reduction is found at the utility supply points, as well as the possible active power flow inversion, entailing contractual and regulatory issues. Extensive short-circuit studies were also carried out, showing that DG fault contribution in the studied network is far from negligible, but does not dictate changes of either circuit breaker rating or overcurrent relaying coordination.

Pengaruh Perbandingan Konstruksi Stator terhadap Tegangan Keluaran Generator Linier

Kondisi dengan banyak pulau ini merupakan kondisi yang menjadimasalah unik bagi pemerataan listrik sekaligus tantangan bagi PLN. Maka dari itu butuh sesuatu pembaruan dalam sistem pembangkit tenaga listrik yang lebih praktis, efisien, dan juga mudah dalam perawatan serta dapat digunakan untuk pulau pulau yang terpencil di indonesia. Generator adalah suatu mesin yang digerakkan secara mekanis oleh penggerak mula misalnya turbin uap, turbin hidrolik, atau mesin disel dan menghasilkan energi untuk lampu listrik atau mesin-mesin yang lain. Penelitian ini bertujuan untuk mengetahui perbandingan desian stator tipe radial dengan desain stator tipe linier. Kemudian membahas tentang pembuatan generator liner dan juga perbandingan 3 buah stator yang berbeda jumlah lilitan, celah udara, serta desainnya. Penelitian ini menggunakan jenis lilitan yang berbeda yaitu lilitan berdiameter 0,8 dan 0,4 mm.Pada stator 1 menggunakan lilitan berdiameter 0,8 jumlah lilitannya 70 lilitan, dapat menghasilkan tegangan keluaran 160 mV pada kecepatan 200 Rpm. Kemudian pada 450 Rpm menghasilkan tegangan maksimal 550 mV. Pada stator ke 2 menggunakan lilitan berdiameter 0,4 dengan jumlah lilitan 200 lilitan, dapat menghasilkan tegangan 134 mV pda kecepatan 200 Rpm. Kemudian pada kecepatan 450 Rpm menghasilkan 560 mV. Pada stator ke 3 mengunakan lilitan 0,4 mm dengan jumlah lilitan 200 lilitan, dapat menghasilkan tegangan keluaran 2 V pada kecepatan 200 Rpm. Kemudian pada kecepatan 500 Rpm menghasilkan 3,3 V tegangan keluaran.

Determination of Atmospheric Krypton and Xenon by Gas Chromatography-Mass Spectrometry in Direct Injection Mode

Abstract Volume concentration determination of atmospheric krypton and xenon is very important for krypton-85 and radioactive xenon isotopes monitoring. An injection set-up integrated adjustable quantity sample injection and quantitative dilution function was designed. The effects of electron impact (EI) source parameters on the sensitivity of MS detector were studied. Optimal values were as follows: ionization energy of 70 eV, emission current of 40 mA, cathode voltage of 27 mV, ion focus voltage of 85 mV and lens compensation voltage of 20 V. A GC-MS method for the determination of krypton and xenon in atmosphere without sample pretreatment was developed. Minimal detected concentrations for krypton and xenon were 3.3 × 10−8 (V/V) and 2.6 × 10−9 (V/V) respectively. Moreover, krypton and xenon concentrations in the ground level air were measured with the results of 1.1 × 10−6 (V/V) and 9.3 × 10−8 (V/V). The related combined standard uncertainties for krypton and xenon results were 2.38% and 3.15%, respectively.

A Successive-Approximation Switched-Capacitor DC–DC Converter With Resolution of for a Wide Range of Input and Output Voltages

A fully integrated successive-approximation (SAR) switched-capacitor (SC) DC-DC converter is presented that overcomes the coarse output voltage resolution limitation of traditional SC converters. An SAR SC converter cascades multiple stages of 2:1 SC converters, and achieves a fine-grained conversion ratio resolution of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IN</sub> /2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sup> , where V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IN</sub> is the input voltage and N is the number of stages. As the SAR SC converter generates the output voltage through SAR, each stage of 2:1 SC converter provides a fixed voltage level, requiring minimal configuration change for regulation. Analysis shows that the SAR SC converter has a slow-switching-limit output impedance increasing proportionally to log <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (number of resolution), and switching loss of bottom-plate parasitic capacitor decreasing with the number of stages. As a test chip, an SAR SC converter with 7 b resolution is fabricated in 180 nm CMOS process and implemented by cascading 4:1 and five 2:1 two-phase interleaving SC stages. It achieves 31.25 mV voltage resolution with output voltages over 0.4 V at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IN</sub> = 4 V. Using this fine grain voltage regulation approach, line and load regulations are implemented with a feedback/feedforward controller with peak efficiency of 72% for load currents from 0 to 300 μA. The test chip occupies 1.69 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and utilizes on-chip capacitors of 2.24 nF in total.

Novel D–π–A porphyrin dyes with different alkoxy chains for use in dye-sensitized solar cells

A series of novel zinc porphyrin dyes which are featured with a D–π–A structure have been designed and synthesized for use in dye-sensitized solar cells (DSSCs). The influences of different hydrophobic hydrocarbon chains (none, butoxy, octoxy groups) attached at the porphyrin meso-aryl group on the molecules’ photophysical and electrochemical properties, as well as on the photovoltaic performance of the corresponding DSSCs were investigated systematically. The best performance was realized for the cell sensitized with the porphyrin (LP-2) containing a n-butoxy chain on the meso-aryl group and with the acrylic acid as the acceptor. The optimized power conversion efficiency of LP-2 reaches 6.04% with an open-circuit voltage of 730 mV, a short-circuit current density of 11.67 mA cm−2, and a fill factor of 0.71.

Inverse dynamic analysis type of MPPT control strategy in a thermoelectric-solar hybrid energy harvesting system

This study presents the development of a novel inverse dynamic analysis-maximum power point tracking (IDA-MPPT) scheme in a hybrid energy harvesting system between thermoelectric module (TEM) and solar array (SA). The proposed method initially changes the harvested voltage response from both sources to be the third-order exponential function. This input function selection is based on the capability of this function to stabilize the initial response system and maintain its final position despite a prolonged response time. The mV voltage value from TEM is easily boosted up to nearly 5 V using this method. With this hybridization, the total obtained voltage is doubled to become 9.7 V, which results in a total power of 0.722 W. Furthermore, the method also allows for a fast tracking system, which enables faster voltage boosting and supercapacitor charging. The supercapacitor only requires less than 5 min to complete charging and boost the voltage to almost 5 V. Thus, a satisfactory value is obtained as compared with that of the TEM system with a chosen MPPC board.

Effect of Trimethyltin Chloride on Slow Vacuolar (SV) Channels in Vacuoles from Red Beet (Beta vulgaris L.) Taproots.

In the present study, patch-clamp techniques have been used to investigate the effect of trimethyltin chloride (Met3SnCl) on the slow vacuolar (SV) channels in vacuoles from red beet (Beta vulgaris L.) taproots. Activity of SV channels has been measured in whole-vacuole and cytosolic side-out patch configurations. It was found that addition of trimethyltin chloride to the bath solution suppressed, in a concentration-dependent manner, SV currents in red beet vacuoles. The time constant, τ, increased significantly in the presence of the organotin. When single channel activity was analyzed, only little channel activity could be recorded at 100 μM Met3SnCl. Trimethyltin chloride added to the bath medium significantly decreased (by ca. threefold at 100 μM Met3SnCl and at 100 mV voltage, as compared to the control medium) the open probability of single channels. Single channel recordings obtained in the presence and absence of trimethyltin chloride showed that the organotin only slightly (by <10%) decreased the unitary conductance of single channels. It was also found that Met3SnCl significantly diminished the number of SV channel openings, whereas it did not change the opening times of the channels. Taking into account the above and the fact that under the here applied experimental conditions (pH = 7.5) Met3SnCl is a non-dissociated (more lipophilic) compound, we suggest that the suppression of SV currents observed in the presence of the organotin results probably from its hydrophobic properties allowing this compound to translocate near the selectivity filter of the channel.

(Invited) Refractory Ceramic Sensors for Process and Health Monitoring of Slagging Gasifiers

Refractory oxide-silicide based composite ceramic thermocouples have been successfully deposited on alumina substrates by a screen printing technique and subsequently thermal processed without any delamination or micro-cracks for the application of health monitoring of slagging gasifier refractory. The phase formation and microstructure are studied by X-Ray Diffraction (XRD) technique and Scanning Electron Microscopy (SEM). The thermoelectric response of the thermocouples was measured by typical hot-cold junction temperature measurements using secondary thermocouples. The thermocouple with a configuration of 90 vol % MoSi2-10 vol% Al2O3 versus 90 vol % WSi2-10 vol% Al2O3 showed a near linear thermoelectric response and a peak thermoelectric voltage of 12.5 mV and Seebeck voltage of 40 µV/°C at 800 °C. The better performance of the thermocouple is correlated to dense microstructure, good adhesion of the temperature sensor with alumina substrate and the optimum electron-phonon interactions at higher temperature.

Modulating the Anionic-Electronic Transport Kinetics to Trigger Memristance for Resistive Switching Non-Volatile Memories: New Materials, Structering and Methods

Bipolar resistive switches were recently proposed as a new class of non-volatile switches capable of reading, writing and erasing memory information by switching non-linearly between low- and high-resistance values by application of mV voltage pulses in the ns range. In the last years, resistive switching has been reported for various classes of materials ranging from sulfides to oxides. Despite their promises oxide-based resistive switches are rarely connected in their diffusion kinetics and constants to the memristive device performance characteristics under bias. In particular, models to describe the mixed anionic-electronic defect contributions for two-carrier systems are missing; this difficults the material selection criteria for best performing devices beyond classic gate oxide selection. Firstly, we report on how to probe carrier diffusion characteristics and memristance for mixed anionic-electronic resistive switches and their oxide materials for the newly proposed Memristor-based Cotrell analysis. For this, we fabricated 2-terminal Pt|SrTiO3-δ|Pt cross-bar array structures as a model system in terms of its mixed defects which show stable and reproducible resistive switching. Secondly, new material engineering of oxides are discussed to control resistive switching device properties like retention, Ron/Roff ratios and power consumption by "interfacial strain engineering of mixed conducting oxide" is reported. Lattice strain engineering using heterostructures at internal interfaces can be used to tune material properties in micro-dots as new resistive switching archiectures far beyond the change accessible by doping. We exemplify the switching characteristics based on either comprsively or tensily strained Gd0.1Ce0.9O2-x heterolayers by Er2O3 or Sm2O3 monolayer modulation, respectively. Thirdly, the role of grain boundaries is discussed for epitaxially and nm-roughness grown LaFeO3 thin film resistive switches with controlled defect levels. We compliment classic resistive switching tests characterizing the near order Raman vibrational (ionic bonding), direct and non-linear optic spectroscopy techniques (electronic contributions).

A power management system architecture for LF passive RFID tags

This paper presents a low power, low voltage power management (PM) system for low-frequency passive RFID tags in a standard CMOS 0.18 µm technology. Passive tags have no internal power source but use the incoming RF energy transmitted by a transceiver to power all the circuitry inside them via a rectifier. Due to the wide variation of the rectified voltage as a function of the RF power, two stages of regulation are required: a shunt regulator working as limiter (3 V) at the rectifier output, and a LDO regulator at a tighter range of 1.15 V. Besides that, two blocks monitor the available RF power at the LDO regulated output and flag when the power is low for different tag operation modes: power-on reset during a read event, and power flag during a write event. All blocks rely on a low power resistor-less 3.5 nA current reference and a 400 mV voltage reference. Both references make use of the self cascode MOSFET structure. The complete PM system is functional with 2 µA current.

Reference voltage divider designed to operate with oscilloscope to enable determination of ratio error and phase displacement frequency characteristics of MV voltage transformers

The goal of the paper is to demonstrate that simple and cost effective resistive voltage divider compensated with capacitance can provide high accuracy transformation of MV voltage in a wide frequencies range. Therefore, it may be applied in the measuring system with the oscilloscope as a reference voltage dividers to determine accuracy of transformation of distorted and sinusoidal voltages up to 20kHz by the 2kV/100V voltage transformers. This thesis is supported by determined in developed wattmeter-based measuring system constructed 2kV/100V voltage dividers and inductive voltage transformer ratio and phase errors frequency characteristics. Differential measurements of rms values and phases between output voltages of two produced voltage dividers with same voltage ratio were carried out in order to verify the accuracy of ratio and phase errors frequency characteristics determination.

Set up and characterization of a measuring system for PQ measurements in a MV site with PV generation

The features of a Power Quality measurement system which includes both voltage and current transducers and a self-developed measuring instrument are described. The system is intended for measurements in substations at medium voltage level. A Rogowski coil and a voltage divider are the used transducers, whereas the measuring instrument is based on a Reconfigurable I/O-FPGA system with embedded software. Attention is focused on the procedures adopted for the characterization of the voltage and current sensors, which are carried out taking into account the expected on-site measurement conditions. An example of use of the systems for measurement of some PQ parameters in a private substation which connects an industrial load and two photo-voltaic generation plants to the public MV voltage network is presented, together with the associated voltage and current uncertainty budget. By making use of the results obtained in the characterization phase, the current and voltage measurement uncertainty can be reduced.

Gβγ Subunits Modulation of Kv7.4 Channels Expressed in HEK293 Cells at the Single Channel Level

Recently it was shown that KCNQ4-encoded voltage-dependent potassium channels (Kv7.4) play an important role in the regulation of resting vascular tone and in response to endogenous vasodilators (Hypertension, 59:877–884, 2012). However there is lack of information about Kv7.4 basic biophysical properties on the single channel level and about their regulatory mechanisms. Therefore, using standard cell-attached and inside-out configurations of the patch-clamp technique we investigated the single channel properties of Kv7.4 in HEK293 cells stably expressing the channel. We found that NPo of Kv7.4 was 0.61±0.05 (n=9, mean±SEM) in the cell-attached configuration at −50 mV (voltage applied to the patch pipette), whereas in the inside-out configuration at 0 mV NPo of Kv7.4 was 0.04±0.01 (n=9). Based on the inside-out experiments, single channel conductance of Kv7.4 was calculated as 2.31 pS. Linopirdine (10 µM), the pan-Kv7 blocker, abolished the single channel activity in both cell-attached and inside-out configuration when added to the patch pipette, but did not produce significant changes when applied to the bath solution. Bath application of PI(4,5)P2 (1 µM) to the inside-out patches or application of active Gβγ subunits (50 ng/ml) resulted in significant increase of NPo of Kv7.4 correspondingly to 0.27±0.09 (n=3) or to 0.34±0.06 (n=6) without affecting channel conductance (p<0.001 in both cases, determined by 2-way ANOVA). Moreover, bath application of gallein (100 µM), an inhibitor of Gβγ activity, reduced significantly NPo of Kv7.4 channels to 0.03±0.01 (n=3, p<0.001) in the cell-attached experiments. Apart from revealing the basic biophysical properties of single Kv7.4 channels our results show that, similar to PI(4,5)P2, Gβγ subunits play a critical role in the basal activity of voltage-dependent Kv7.4 channels.Supported by the British Heart Foundation (PG/12/63/29824) and by the Medical Research Council (MR/K019074/1).