Chunrong Peng

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.

A Novel High Performance Micromechanical Resonant Electrostatic Field Sensor Used In Atmospheric Electric Field Detection

This paper reports a high performance micromechanical resonant electrostatic field sensor (EFS) that is fabricated with a three-layer polysilicon surface micromachining process. The EFS has a high resolution of 100V/m when used in ambient air at room temperature. The driving voltage is 25V DC and 0.3Vp-p AC lower than other reported electrostatic comb driven devices. Experimental results show that the EFS can be succeeded in atmospheric electric field detecting.

A high sensitivity SOI electric-field sensor with novel comb-shaped microelectrodes

We have developed a highly sensitive electric-field sensor with novel comb-shaped microelectrodes. The sensor is based on modulating an incident field with a grounded shutter and measuring the induced charge of sensing electrodes. Owing to the shutter covering the side wall of the sensing electrodes, the fringing fields are no longer a factor that reduces the performance of the sensor. Moreover, in order to improve the efficiency of the charge induction, comb-shaped microelectrodes are introduced. The sensor can measure not only electrostatic field, but also AC field. Tested in ambient air conditions, the minimum detectable field of the sensor is approximately 40V/m with an uncertainty of 1% in DC electric field range 0–50kV/m and 10V/m for a 50Hz AC field. Finally, the use of the sensor to detect ice accretion on high power electric cables is achieved.

Design, fabrication and application of an SOI-based resonant electric field microsensor with coplanar comb-shaped electrodes

This paper presents a highly sensitive resonant electric field microsensor based on silicon on insulator (SOI) technology. To improve the electric field coupling effect, the microsensor uses coplanar shutter electrodes and sense electrodes. To obtain higher conversion gain, both electrodes adopt novel comb-shaped structures. A finite element method (FEM) was used to simulate and optimize the structures of the comb-shaped electrodes. The sensitivity model of the microsensor was analyzed by the conversion gain of the vibration-amplitude-to-charge variation. The resolution of the microsensor is approximately 40 V m−1 with an uncertainty of 1% for the dc field, while the resolution is better than 10 V m−1 for the 50 Hz ac field. The microsensors were packaged and assembled to form an electric field probe to measure the atmospheric electric field. The test results showed that the probe precisely detected the occurrence of thunderstorms, and the plotted data agreed well with those of the conventional electric field mill.

Design of a SOI MEMS resonant electric field sensor for power engineering applications

This paper presented a novel resonant electric field sensor (EFS) based on SOI fabrication process for power engineering applications. The sensor architecture has three major blocks: a vibration shutter, sensing electrodes, and a driving electrode that feeds back to the shutter. The EFS structure is designed to work at resonant frequency for maximum sensitivity to electric fields. Prototyped by the SOI fabrication process, the device gives quality factor (Q) of approximately 31034 at a vacuum degree of ∼1mTorr with lower actuation voltages (i.e., 250mV DC and 20mVp-p) than other reported electrostatic driven EFS. Tested in ambient air conditions, the device has an improved uncertainty of 1.09% in a measured range of 0–50kV/m DC electric field. A minimum detectable DC electric field with current sensor designs better than 50V/m is also achieved. In addition, the sensor can also be measured AC electric field.

Detecting internal defect of non-ceramic insulators using a novel micromachined electric field sensor

The paper presented a novel MEMS (Microelectro-mechanicalsystems) electric field sensor (EFS) based on SOI (Silicon on Insulator) fabrication process for detecting internal defect of non-ceramic (composite) insulators. The ability to measure both AC and DC electric field is a significant advantage of this sensor in comparison to other sensors, which can only measure either AC or DC electric field. The MEMS structure is designed to work at resonant frequency for maximum sensitivity to electric fields. Prototyped by the SOI fabrication process, the device gives high quality factor (Q) of approximately 31034 at a vacuum degree of ∼1mTorr with lower actuation voltages (i.e., 250mV DC and 20mVp-p). The sensing area of this sensor is only 5mm×5mm and it requires only less than 1µW to drive its shutter. Tested in ambient air conditions, a minimum detectable DC and AC electric field with current sensor designs better than 50V/m is also achieved. The use of a miniature sensor also helps to measure local electric field around insulators accurately since the field distortion caused by the sensor is minimum. Experiments show that the EFS probe can be succeeded in detecting the internal defect of non-ceramic insulators remotely.

A novel MEMS chip-based atmospheric electric field sensor for lightning hazard warning applications

This paper presents a novel atmospheric electric field sensor based on high sensitivity resonant MEMS (microelectromechanical systems) electric field sense chips, which resolves the problems of motor wear, high power consumption and failure rate of the conventional electric field mill. The chip was fabricated in a commercial SOIMUMPS process. The sensor overall structure scheme was proposed and the phase-sensitive detection method was used for extract the chip output signal. A special protective structure was designed for protecting the sensor against the influences of the external environment. The minimum detectable electric field of the sensor is 10V/m with an uncertainty of 0.67% in the range of 0~50kV/m, and its power consumption is only 0.62w. The outdoor test showed that the plotted data of the sensor agreed well with those of the conventional electric field mill on both sunny day and thunderstorm day, which indicates that the developed sensor can meet the applications of lighting hazard warning.

A novel 2-dimensional electric field sensor based on in-plane micro rotary actuator

This paper, for the first time, proposes a 2-dimensional electric field sensor based on in-plane micro rotary actuator. Compared to the existent electric field micro sensors, which can only detect an axial direction electric field, this sensor is capable of 2-dimensional electric field sensing. In the design of the micro sensor, the combination of angular comb-drives and serpentine springs can bring the advantage of achieving large in-plane rotation, which enlarges the vibration amplitudes and results in more induced charges. Moreover, both push-pull electrostatic actuation method and differential sensing electrodes are adopted to expand the vibration magnitudes and reduce the impact of common mode interference. Experimental results show that this sensor has good linearity of 1.21% in a wide range, and this sensor can detect the X and Y component of electric field with measurement errors better than 8%.

Three dimensional electric field measurement method based on coplanar decoupling structure

This paper proposes a simple and precise way to measure three dimensional (3D) electric field (E-field). By means of creating and deriving a coupling sensitivity matrix, the 3D E-field can be accurately measured by using three electric field sensing elements distributed on a plane. The cross interferences between these sensing elements can be effectively eliminated. Finite element simulations and experiments have demonstrated that the measured result is accurate for any random rotation angle.

A High Sensitivity Electric Field Microsensor Based on Torsional Resonance

This paper proposes a high sensitivity electric field microsensor (EFM) based on torsional resonance. The proposed microsensor adopts torsional shutter, which is composed of shielding electrodes and torsional beams. The movable shielding electrodes and the fixed sensing electrodes are fabricated on the same plane and interdigitally arranged. Push–pull electrostatic actuation method is employed to excite the torsional shutter. Simulation results proved that the torsional shutter has higher efficiency of charge induction. The optimization of structure parameters was conducted to improve its efficiency of charge induction further. A micromachining fabrication process was developed to fabricate the EFM. Experiments were conducted to characterize the EFM. A good linearity of 0.15% was achieved within an electrostatic field range of 0–50 kV/m, and the uncertainty was below 0.38% in the three roundtrip measurements. A high sensitivity of 4.82 mV/(kV/m) was achieved with the trans-resistance of 100 MΩ, which is improved by at least one order of magnitude compared with previously reported EFMs. The efficiency of charge induction for this microsensor reached 48.19 pA/(kV/m).