Electrostatic Field Sensor Research Articles

An analytical model of the detecting structure of electrostatic inductive electric field sensor

To analyze and design the detecting structure of electrostatic inductive electric field sensors, it is crucial to determine the capacitance. This study proposes a model for the theoretical analysis of the capacitance of the detecting structure of the electrostatic inductive electric field sensor. The aim is to achieve high calculation accuracy and deepen the fundamental understanding of high performance. Using Schwarz–Christoffel mapping, a reasonably simplified and approximative solution program is developed. The precision is comparable to that of a finite element solver. The calculation results exhibit good agreement with the simulation results from finite element analysis when various parameter ratios are used. Notably, the calculation results of the analytical model are verified by the measured data of a realistic electrostatic sensor. Using the analytical model, a parametric study of the detecting structure is conducted, leading to the determination of the final optimized, technically achievable device structures.

A Highly Sensitive and High-Resolution Resonant MEMS Electrostatic Field Microsensor Based on Electrostatic Stiffness Perturbation.

This paper proposes a highly sensitive and high-resolution resonant MEMS electrostatic field sensor based on electrostatic stiffness perturbation, which uses resonant frequency as an output signal to eliminate the feedthrough interference from the driving voltage. The sensor is composed of a resonator, driving electrode, detection electrode, transition electrode, and electrostatic field sensing plate. The working principle is that when there is an electrostatic field, an induction charge will appear at the surface of the electrostatic field sensing plate and induce electrostatic stiffness on the resonator, which will cause a resonant frequency shift. The resonant frequency is used as the output signal of the microsensor. The characteristics of the electrostatic field sensor are analyzed with a theoretical model and verified by finite element simulation. A device prototype is fabricated based on the Silicon on Insulator (SOI) process and tested under vacuum conditions. The results indicate that the sensitivity of the sensor is 0.1384Hz/(kV/m) and the resolution is better than 10 V/m.

Noncontact Human Body Voltage Measurement Using Microsoft Kinect and Field Mill for ESD Applications

A technique for measuring the voltage on a person by combining an overhead mounted electrostatic field sensor with Microsoft Kinect image recognition software and hardware is presented in this paper. The Kinect's built-in skeleton detection method was used to determine the posture, height, and location of a person relative to the position of the field sensor. The voltage is estimated using field strength and geometry information. Two different algorithms are proposed for calculating the human body voltage using field strength data captured by the field sensor and human body coordinates recognized by the Kinect. First, using calibration data, the human body voltage was obtained by charging a person to a known voltage and walking through the field of vision, then a correction was performed to convert the field sensor data into the human body voltage. The second algorithm is based on solving Laplace equation. The human body is modeled by using a superposition of spheroids, and the E-field is solved analytically. Results of the algorithms were compared, with the proposed methodology providing less than a ±15% error margin for the human body voltage over a detection area of 2.0 m × 2.5 m.

MEMS-based non-contact voltage sensor with multi-mode resonance shutter

Miniature non-contact voltage sensor has significant benefit for condition monitoring of power systems in terms of ease of installation and a minimum disturbance to an existing design. The electrostatic field sensor miniaturized by MEMS (Micro Electro Mechanical Systems) technology is a promising method to realize low cost and small sensors. However, the behavior of micro-sized mechanical shutter under an intense electric field and performance as a voltage sensor are barely studied. Here, we design the SOI (Silicon on Insulator) based shutter which has multiple vibration modes, evaluate the performance under an intense electric field (˜1.4 MV/m). The vibration spectrum obtained by sensor output shows a resonance frequency shift and a non-linearity of sensitivity. These results are explained by a numerical model which consider a vertical displacement of shutter due to the tensile force from an electric field. Finally, practical demonstrations are carried such as a calibration for linear response using multiple linear regression analysis of sensor outputs with various resonance mode and evaluation of sensor bandwidth with a synthesized sinusoidal and rapid change of an electric field for a quantitative comparison with past studies.

High-Performance Graphene-Based Electrostatic Field Sensor

Electrostatic sensing technology is widely utilized in both military and civilian applications, including electrostatic prevention in gas stations and various electronic devices. The high sensitivity of electrostatic sensor is capable to detect not only weak electrostatic charges, but also the weak disturbance of electrostatic field in distant. Here, we present a high-performance graphene-based electrostatic sensor. Combining the ultrahigh mobility of graphene and the long lifetime of carriers in lightly doped SiO2/Si substrate, our device achieves a fast response of ~2 us and detection limit of electrostatic potential as low as ~5 V, which is improved by an order of magnitude as compared to commercial product. The proposed device structure opens a promising pathway to high-sensitive electrostatic detection, and also greatly facilitates the development of novel sensors, e.g. portable and flexible electrostatic sensor.

A novel easy-driving and easy-signal-processing electrostatic field sensor based on a piezoresistance and polyethylene terephthalate lever

A novel electrostatic field sensor with compact structure and a simple signal processing circuit is proposed in this paper. The sensor is based on a piezoresistive force meter and a lathy polyethylene terephthalate (PET) lever for electrostatic force generation and transformation. The force meter with a rectangular membrane supported by four beams was fabricated and one end of the PET lever was attached to the center of the membrane surface. The other end of the lever was free for electrostatic force generation. Only a low voltage DC source was required for the whole sensor, rather than sophisticated driving circuits. The lever magnified the electrostatic force effecting upon the force meter, and thus the output of the sensor was large enough for a simple processing circuit to be sufficient, rather than requiring complicated instruments. Characteristics of the sensor formation make it appropriate to adopt this sensor in various applications, in particular in high voltage power systems monitoring and meteorology measurements. The experiment results showed agreement with simulation results of the sensor. Sensitivity of the prototype of this sensor was 0.06 √mV (kV · m−1)−1 which can be greatly promoted by design optimization and fabrication improvement.

振動型静電界センサによる空気輸送粉体の帯電量評価

振動型静電界センサによる空気輸送粉体の帯電量評価

A novel high-sensitivity electrostatic biased electric field sensor

In this paper, an electric field sensor (EFS) with high sensitivity is proposed for low-frequency weak-strength ac electric field (E-field) measurements. The EFS is based on a piezoelectric cantilever biased by a strong electrostatic field. The electrostatic bias can enhance the electric field force of a weak ac E-field, thus the cantilever can oscillate in a weak ac E-field and the device sensitivity improves. Theoretical analyses have been established and suggest that a stronger strength of electrostatic field bias would produce a higher sensitivity improvement. In the experiment, a demonstrated sensor consisting of a polyvinylidene fluoride (PVDF) piezoelectric cantilever and a polytetrafluoroethylene (PTFE) electret was built and tested. Instead of extra voltage sources, the PTFE electret was charged to provide the electrostatic field, allowing the EFS a low energy consumption and a simple electric circuit design. The experiment results show good agreement with the simulation. The sensitivity of the cantilever E-field sensor reached 0.84 mV (kV/m)−1 when the surface potential of the electret was −770 V.

振動型静電界センサ内の送風の電界強度計測への影響

振動型静電界センサ内の送風の電界強度計測への影響

A MEMS-Based Electrostatic Field Sensor Using Out-of-Plane Thermal Actuation

In this paper, we report a MEMSbased electrostatic field sensor (EFS) using out-of-plane thermal actuation. The EFS mainly consists of shuttles, sensing electrodes, and clamp-clamp beams. The clamp-clamp beam with a hump is treated as thermal actuator to drive the shuttle, which is to modulate the external electrostatic field. The EFS was fabricated by a standard surface micromachining process and the area of the EFS is less than 2.5mm×2.5mm. The EFS has been tested and achieved a resolution of 60V/m.

An electrostatic field sensor operated by self-excited vibration of MEMS-based self-sensitive piezoelectric microcantilevers

We have developed MEMS-based electrostatic field sensors (MEMS-EFS) composed of probe to detect electrostatic field and self-sensitive piezoelectric microcantilevers. The self-sensitive piezoelectric microcantilevers have Pb(Zr,Ti)O3 (PZT) thin films for sensor and actuator. The MEMS-EFS were fabricated through sol–gel deposition of PZT thin films and MEMS microfabrication process. An output voltage of the PZT thin films for sensor was found to be proportional to the displacement of the microcantilevers. Self-excited vibration of the microcantilevers has been achieved by amplifying and forwarding the output voltage of the PZT thin films for sensor with a band pass filter circuit. The developed MEMS-EFS can evaluate an electrostatic field of −3 to 3kV with good linearity.

Self-ignition of hydrogen releases through electrostatic discharge induced by entrained particulates

Abstract The potential for particulates entrained in hydrogen releases to generate electrostatic charge and induce electrostatic discharge ignitions was investigated. A series of tests were performed in which hydrogen was released through a 3.175-mm diameter orifice from an initial pressure of 140 bar. Electrostatic field sensors were used to characterize the electrification of known quantities of iron oxide particulates deliberately entrained in the release. The ignition experiments focused on using charged particulates to induce spark discharges from isolated conductors and corona discharges. A total of 12 ignition events were observed. The results show that electrification of entrained particulates is a viable self-ignition mechanism of hydrogen releases.

Operational analysis of electric field mills as lightning warning systems in Colombia

Electrostatic field measurements taken in Bogotá, Colombia, during thunderstorms in November (the rainy season due to inter-tropical confluence zone over central Colombia) were used to study the performance of an isolated electric field sensor and analyse its most important operational characteristics. The distances from each flash to the studied sensor were obtained by using the Colombian lightning location system. The ΔE cf distance ratio led to defining a charge model which could be used as a reference for calibrating other electrostatic field sensors to be used as lightning warning systems.

A novel SOI MOSFET electrostatic field sensor

A novel low temperature solid state electric field sensor is demonstrated as a promising sensor. The sensor is a type of constant voltage Wheatstone bridge whose resistors are four direct gate SOI MOSFET devices. It is demonstrated in theory that the output voltage signal is proportional to the electric field E, the temperature drift is about zero when the temperature is in the range from 200 to 400 K, and the doping concentration is in the range from 1 × 1014 to 1 × 1016 cm−3. The experiment results indicate that the resolution of the sensor is about 3.27 mV for a 1000 V/m electric field at 300 K, and the voltage drift by an amount is about 47 V/m field signal when the degree temperature is in the range from 300 to 370 K, which is much smaller than the current drift of a single MOSFET which is about 10000 V/m field signal.

Design of a novel closed-loop SOI MEMS resonant electrostatic field sensor

A novel closed-loop SOI MEMS resonant electrostatic field sensor (EFS) has been designed in this paper. The sensor architecture has three major blocks: a vibration shutter, sensing electrodes, and a closed-loop driving electrode that feeds back to the shutter. With a phase and an amplitude closed loop feedback control, the sensor can be adjusted automatically to operate at its resonant frequency. Prototyped by the SOI fabrication process, the device has a lower driving voltage and a higher quality factor (Q) over existing electrostatic comb driven EFS. An improved uncertainty of 2.1% is achieved for the SOI device operating in ambient air in a measured range of 0–50 kV/m.

Microelectromechanical Systems-Based Electrostatic Field Sensor Using Pb(Zr,Ti)O3 Thin Films

We have developed microelectromechanical system (MEMS)-based electrostatic field sensors using Pb(Zr,Ti)O3 thin films. Multilayers of Pt/Ti/PZT/Pt/Ti/SiO2 deposited on silicon-on-insulator (SOI) wafers have been fabricated into the sensors through MEMS microfabrication technology. The resonant frequency of the fabricated sensors is within 1700–1800 Hz. The developed MEMS-based electrostatic field sensors have shown a good linear response to the voltage of an electrified body, which is comparable to that of commercially available electrostatic field sensors.

Design and testing of a micromechanical resonant electrostatic field sensor

The design, fabrication and characterization testing of a high-performance micromechanical resonant electrostatic field sensor at low driving voltages is presented. Structures including sensing electrodes, shielding electrodes and suspension beam design are discussed. The electromechanical behavior around the resonant frequency is described by an equivalent electric circuit to predict the output characterization of the sensors. The device is fabricated by a surface micromachining process. With low driving voltages compared with other reported devices, the electrostatic field sensors (EFS) have a resolution of 200 V m−1, the best reported figure for a MEMS-based device used in ambient air at room temperature. A nonlinearity of 1.8% (end-point-straight-line) in a measurement range of 0–10 kV m−1 is achieved. We have also achieved an uncertainty of 4.62% for the measurement data.

Micromechanical electrostatic field sensor for the characterization of charges in MEMS devices

Electrostatic driving and capacitive read-out play an important role in micro-electromechanical system (MEMS). The necessary electrodes are placed on insulating materials and in some cases they are coated with an insulating layer. It has been observed that after electrical breakdown in the air gap or the contact of the movable element and the dielectric layer the characteristic of the MEMS has changed. This is caused by charge deposition on the insulating material and leads to an additional offset voltage. Hence it is very important to investigate the behavior of charges in MEMS devices to derive rules for the design and the fabrication process. The article presents a novel electrostatic field sensor realized using a micromechanical component. It was developed to characterize surface charges on dielectric layers mainly in the region of electrode structures.

Micromechanical electrostatic field sensor for the characterization of charges in MEMS devices

Electrostatic driving and capacitive read-out play an important role in micro-electromechanical system (MEMS). The necessary electrodes are placed on insulating materials and in some cases they are coated with an insulating layer. It has been observed that after electrical breakdown in the air gap or the contact of the movable element and the dielectric layer the characteristic of the MEMS has changed. This is caused by charge deposition on the insulating material and leads to an additional offset voltage. Hence it is very important to investigate the behavior of charges in MEMS devices to derive rules for the design and the fabrication process. The article presents a novel electrostatic field sensor realized using a micromechanical component. It was developed to characterize surface charges on dielectric layers mainly in the region of electrode structures.

Electrostatic charge and field sensors based on micromechanical resonators

We have developed highly sensitive electrometers and electrostatic fieldmeters (EFMs) that make use of micromechanical variable capacitors. Modulation of the input capacitance, a technique used in macroscale instruments such as the vibrating-reed electrometer and the field-mill electrostatic voltmeter (ESV), moves the detection bandwidth away from the 1/f-noise-limited regime, thus improving the signal-to-noise ratio (SNR). The variable capacitors are implemented by electrostatically driven resonators with differential actuation and sensing to reduce drive-signal feedthrough. The resonators in the electrometer utilize a balanced comb structure to implement harmonic sensing. Two fabrication methods were employed - a hybrid technology utilizing fluidically self-assembled JFETs and SOI microstructures, and an integrated process from Analog Devices combining 0.8-μm CMOS and 6-μm-thick polysilicon microstructures. All devices operate in ambient air at room temperature. Measured data from one electrometer with an input capacitance of 0.7 pF indicates a charge resolution of 4.5 aC rms (28 electrons) in a 0.3 Hz bandwidth. The resolution of this electrometer is unequaled by any known ambient-air-operated instrument over a wide range of source capacitances. The EFM has a resolution of 630 V/m, the best reported figure for a MEMS device.