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voltage sensor

Jianping Zhang, Xingjuan Chen, Yucong Xue, Nikita Gamper, Xuan Zhang
Voltage-gated ion channels were believed to be the only voltage-sensitive proteins in excitable (and some non-excitable) cells for a long time. Emerging evidence indicates that the voltage-operated model is shared by some other transmembrane proteins expressed in both excitable and non-excitable cells. In this review, we summarize current knowledge about voltage-operated proteins, which are not classic voltage-gated ion channels as well as the voltage-dependent processes in cells for which single voltage-sensitive proteins have yet to be identified...
April 18, 2018: Journal of Cellular Physiology
Sujoy Ghosh, Niazul I Khan, John G Tsavalas, Edward Song
Selective and rapid detection of biomarkers is of utmost importance in modern day health care for early stage diagnosis to prevent fatal diseases and infections. Among several protein biomarkers, the role of lysozyme has been found to be especially important in human immune system to prevent several bacterial infections and other chronic disease such as bronchopulmonary dysplasia. Thus, real-time monitoring of lysozyme concentration in a human body can pave a facile route for early warning for potential bacterial infections...
2018: Frontiers in Bioengineering and Biotechnology
Hiroaki Miyazawa, Kanoko Okumura, Kanae Hiyoshi, Kazuhiro Maruyama, Hisaya Kakinuma, Ryunosuke Amo, Hitoshi Okamoto, Kyo Yamasu, Sachiko Tsuda
Optical measurement of membrane potentials enables fast, direct and simultaneous detection of membrane potentials from a population of neurons, providing a desirable approach for functional analysis of neuronal circuits. Here, we applied recently developed genetically encoded voltage indicators, ASAP1 (Accelerated Sensor of Action Potentials 1) and QuasAr2 (Quality superior to Arch 2), to zebrafish, an ideal model system for studying neurogenesis. To achieve this, we established transgenic lines which express the voltage sensors, and showed that ASAP1 is expressed in zebrafish neurons...
April 16, 2018: Scientific Reports
Daehee Seol, Sang Mo Yang, Stephen Jesse, Minseok Choi, Inrok Hwang, Taekjib Choi, Bae Ho Park, Sergei V Kalinin, Yunseok Kim
The manipulation of local ionic behavior via external stimuli in oxide systems is of great interest because it can help in directly tuning material properties. Among external stimuli, mechanical force has attracted intriguing attention as novel stimulus for ionic modulation. Even though effectiveness of mechanical force on local ionic modulation has been validated in terms of static effect, its real-time behavior under an application of the force is barely investigated in spite of its crucial impact on device performance such as force or pressure sensors...
April 16, 2018: Nanotechnology
Alar Ainla, Maral P S Mousavi, Maria-Nefeli Tsaloglou, Julia Redston, Jeffrey G Bell, M Teresa Fernández-Abedul, George M Whitesides
This paper describes the design and characterization of an open-source universal wireless electrochemical detector (UWED). This detector interfaces with a smartphone (or a tablet) using Bluetooth Low Energy protocol; the smartphone provides (i) a user interface for receiving the experimental parameters from the user and visualizing the result in real-time, and (ii) a proxy for storing, processing, and transmitting the data and experimental protocols. This approach simplifies the design, and decreases both the size and the cost of the hardware; it also makes UWED adaptable to different types of analyses by simple modification of the software...
April 16, 2018: Analytical Chemistry
Dejan Davidovikj, Menno Poot, Santiago Jose Cartamil-Bueno, Herre S J van der Zant, Peter Gerard Steeneken
For the study and application of graphene membranes, it is essential to have means to control their tension, resonance frequency and temperature. Here, we present an on-chip heater platform for local tuning of in-plane tension in graphene mechanical resonators. By Joule heating of a metallic suspension ring we show thermomechanical resonance frequency tuning in a graphene nanodrum, which is accompanied by an increase in its quality factor, which we attribute to an increase of the in-plane tension. The in-situ control of temperature, in-plane tension, resonance frequency and quality factor of suspended two-dimensional (2D) nanodrums makes this device a unique platform for investigating the origin of dissipation in these ultra-thin structures and can be of fundamental importance for studying the thermal properties of 2D materials...
April 13, 2018: Nano Letters
Malin Silverå Ejneby, Xiongyu Wu, Nina E Ottosson, E Peter Münger, Ingemar Lundström, Peter Konradsson, Fredrik Elinder
Dehydroabietic acid (DHAA) is a naturally occurring component of pine resin that was recently shown to open voltage-gated potassium (KV ) channels. The hydrophobic part of DHAA anchors the compound near the channel's positively charged voltage sensor in a pocket between the channel and the lipid membrane. The negatively charged carboxyl group exerts an electrostatic effect on the channel's voltage sensor, leading to the channel opening. In this study, we show that the channel-opening effect increases as the length of the carboxyl-group stalk is extended until a critical length of three atoms is reached...
April 6, 2018: Journal of General Physiology
Mingxia Jiao, Zimeng Li, Yun Li, Min Cui, Xiliang Luo
An electrochemical sensor for nitrite was fabricated by modifying a glassy carbon electrode (GCE) with the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) that is doped with carbon quantum dots (CQDs). The negatively charged CQDs were doped into PEDOT via electrodeposition to form a conducting polymer nanocomposite on the GCE. The electrode surface has a flake-like nanostructure and a large specific surface area. The elemental mapping analysis revealed that the CQDs are uniformly distributed across the whole nanocomposite...
April 6, 2018: Mikrochimica Acta
Sanghamitra Mandal, M O Manasreh
The purpose of this research was to design an optical sensor for evaluating glycated hemoglobin (HbA1c) percentages in hemoglobin. The A1c sensors available in the market use invasive methods, while our device offers the possibility of non-invasive monitoring of HbA1c levels in diabetic patients. A prototype is assembled using two light emitting diodes with peak emission wavelengths of 535 nm and 593 nm, a photodiode, and a microcontroller. The proposed sensor measures the transmitted intensity in the form of an output voltage...
April 4, 2018: Sensors
Min Seok Song, Su Min Park, Jeong Seok Park, Jin Ho Byun, Hee Jung Jin, Seung Hyun Seo, Pan Dong Ryu, So Yeong Lee
Voltage-gated potassium (Kv) channels, including Kv3.1 and Kv3.4, are known as oxygen sensors, and their function in hypoxia has been well investigated. However, the relationship between Kv channels and tumor hypoxia has yet to be investigated. This study demonstrates that Kv3.1 and Kv3.4 are tumor hypoxia-related Kv channels involved in cancer cell migration and invasion. Kv3.1 and Kv3.4 protein expression in A549 and MDA-MB-231 cells increased in a cell density-dependent manner, and the pattern was similar to the expression patterns of hypoxia-inducible factor-1α (HIF-1α) and reactive oxygen species (ROS) according to cell density, whereas Kv3...
April 2, 2018: International Journal of Molecular Sciences
Wei Tang, Fei Lyu, Dunhui Wang, Hongbing Pan
In this paper, a new single-device three-dimensional (3D) Hall sensor called a cross-shaped 3D Hall device is designed based on the five-contact vertical Hall device. Some of the device parameters are based on 0.18 μm BCDliteTM technology provided by GLOBALFOUNDRIES. Two-dimensional (2D) and 3D finite element models implemented in COMSOL are applied to understand the device behavior under a constant magnetic field. Besides this, the influence of the sensing contacts, active region's depth, and P-type layers are taken into account by analyzing the distribution of the voltage along the top edge and the current density inside the devices...
April 2, 2018: Sensors
Dongping Xiao, Qichao Ma, Yutong Xie, Qi Zheng, Zhanlong Zhang
In this paper, a new type of electric field sensor is proposed for the health and safety protection of inspection staff in high-voltage environments. Compared with the traditional power frequency electric field measurement instruments, the portable instrument has some special performance requirements and, thus, a new kind of double spherical shell sensor is presented. First, the mathematical relationships between the induced voltage of the sensor, the output voltage of the measurement circuit, and the original electric field in free space are deduced theoretically...
March 31, 2018: Sensors
Lianhong Chen, Zhenyuan Sun, Guanglei Li, Deyong Chen, Junbo Wang, Jian Chen
A monolithic electrochemical micro seismic sensor capable of monitoring three-axial vibrations was proposed in this paper. The proposed micro sensor mainly consisted of four sensing units interconnected within flow channels and by interpreting the voltage outputs of the sensing units, vibrations with arbitrary directions can be quantified. The proposed seismic sensors are fabricated based on MEMS technologies and characterized, which produced sensitivities along x , y , and z axes as 2473.2 ± 184.5 V/(m/s), 2261...
March 31, 2018: Sensors
H Mahmoodzadeh, B Rezaei
Using the transfer matrix method, the transmission properties of defective one-dimensional photonic crystal are analyzed in the terahertz region. The defect layer is composed of a graphene-embedded dielectric layer. We investigate the variation of the defect mode's frequency as a function of graphene chemical potential for different values of incident angles. The numerical results show that the frequency of the defect mode can be tuned effectively as the chemical potential of graphene nanolayers changes using an applied gate voltage...
March 20, 2018: Applied Optics
Thérèse Barbier, Sarra Aissani, Nicolas Weber, Cédric Pasquier, Jacques Felblinger
PURPOSE: To evaluate the function of an active implantable medical device (AIMD) during magnetic resonance imaging (MRI) scans. The induced voltages caused by the switching of magnetic field gradients and rectified radio frequency (RF) pulse were measured, along with the AIMD stimulations. MATERIALS AND METHODS: An MRI-compatible voltage probe with a bandwidth of 0-40 kHz was designed. Measurements were carried out both on the bench with an overvoltage protection circuit commonly used for AIMD and with a pacemaker during MRI scans on a 1...
March 30, 2018: Magma
Jiyu Wang, Wenbo Ding, Lun Pan, Changsheng Wu, Hua Yu, Lijun Yang, Ruijin Liao, Zhong Lin Wang
The development of internet of things (IoT) has brought new challenges to the corresponding distributed sensor systems. Self-powered sensors which can perceive and respond to environmental stimuli without an external power supply are highly desirable. In this paper, a self-powered wind sensor system based on an anemometer triboelectric nanogenerator (a-TENG, free-standing mode) and a wind vane triboelectric nanogenerator (v-TENG, single-electrode mode) is proposed for simultaneously detecting wind speed and direction...
March 29, 2018: ACS Nano
Junjun Luo, Dan Zhao, Minghui Yang, Fengli Qu
A glassy carbon electrode was modified with an array of porous Ni3 N nanosheets (Ni3 N NA) and studied for its use in non-enzymatic electrochemical detection of glucose. The morphology and structure of the Ni3 N NA were characterized by scanning electron microscopy and X-ray diffraction. Electrochemical studies demonstrated that the Ni3 N NA acts as an efficient catalyst for the electro-oxidation of glucose at pH 13, best at a working voltage of 0.55 V (vs. Ag/AgCl). Figures of merit include (a) high sensitivity (39 μA·mM-1 ·cm-2 ), (b) a low limit of detection (0...
March 19, 2018: Mikrochimica Acta
Hui Wang, Yang Liu, Gang Liu
The article describes a reusable biosensor for Pb(II) ions. A duplex DNA with a terminal amino group and containing a G-quadruplex (G4) aptamer was covalently conjugated to single walled carbon nanotubes on a field effect transistor (FET). The detection scheme is based on the despiralization of the DNA duplex because Pb(II) can induce the G4 aptamer to form a stabilizing G4/Pb(II) complex. This structural change affects the electrical conductivity of SWNTs which serves as the analytical signal. The biosensor was characterized via scanning electron microscopy, Raman, UV-vis, and voltage-current profiles...
January 29, 2018: Mikrochimica Acta
Wei Wang, Silambarasan Jayachandran, Mengru Li, Shenghao Xu, Xiliang Luo
An electrochemical biosensor for the detection of microRNA was prepared via chemical grafting of a Methylene Blue labeled reporter (MB-Rep) duplex onto a nanostructured surface that was obtained by electrodeposition of cobalt oxide and poly(o-phenylenediamine). This is followed by the attachment of hyaluronic acid and gold nanoclusters. In the presence of the target (microRNA), the probe-target duplex and the MB-Rep hairpin are formed. These will displace the labeled reporter from the sensor surface, and this results in a decrease of the amperometric signal for MB at a typical working voltage of -0...
February 5, 2018: Mikrochimica Acta
Solleti Goutham, Satish Bykkam, Kishor Kumar Sadasivuni, Devarai Santhosh Kumar, Mohsen Ahmadipour, Zainal Arifin Ahmad, Kalagadda Venkateswara Rao
A nanocomposite consisting of a few layers of graphene (FLG) and tin dioxide (SnO2 ) was prepared by ultrasound-assisted synthesis. The uniform SnO2 nanoparticles (NPs) on the FLG were characterized by X-ray diffraction in terms of lattice and phase structure. The functional groups present in the composite were analyzed by FTIR. Electron microscopy (HR-TEM and FE-SEM) was used to study the morphology. The effect of the fraction of FLG present in the nanocomposite was investigated. Sensitivity, selectivity and reproducibility towards resistive sensing of liquid propane gas (LPG) was characterized by the I-V method...
December 20, 2017: Mikrochimica Acta
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