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).

One of the major concerns in the development of three-dimensional (3D) electric field sensors (EFSs) is their susceptibility to cross-axis coupling interference. The output signal for each sensing axis of a 3D EFS is often coupled by electric field components from the two other orthogonal sensing axes. In this paper, a one-dimensional (1D) electric field sensor chip (EFSC) with low cross-axis coupling interference is presented. It is designed to be symmetrical, forming a pair of in-plane symmetrically-located sensing structures. Using a difference circuit, the 1D EFSC is capable of sensing parallel electric fields along symmetrical structures and eliminating cross-axis coupling interference, which is contrast to previously reported 1D EFSCs designed for perpendicular electric field component measurement. Thus, a 3D EFS with low cross-axis coupling interference can be realized using three proposed 1D EFSCs. This 3D EFS has the advantages of low cross-axis coupling interference, small size, and high integration. The testing and calibration systems of the proposed 3D EFS were developed. Experimental results show that in the range of 0–120 kV/m, cross-axis sensitivities are within 5.48%, and the total measurement errors of this 3D EFS are within 6.16%.

Electric field abnormal is one of the most important earthquake precursor phenomena in the ionosphere. The ionosphere electric field abnormal has the characteristic of wide frequency band (frequency range from DC to several MHz), which is suitable to be detected by the double-probe spaceborne electric field sensor (DSEFS). The DSEFS is composed of four sensing probes, four booms outside of the satellite and one signal acquisition and processing system (SAPS) inside the satellite. The four booms are used to set the four probes away form the satellite platform and form a tetrahedron in the space. The plasma potential around the probe is coupled to the probe though equivalent resistor and capacitor in parallel, which is the result of the probe charging. The plasma potential is acquired with a preamplifier with very high input impedance in the probe. In order to insure the detection precision, the value of equivalent resistor can be adjusted with a bias current provided by the SAPS. The probe potential is further acquired and processed by the SAPS to form three dimensional orthogonal electric field detection results. In order to insure the detection precision of the plasma electric field, the Spacecraft and Plasma Interaction System (SPIS) simulation software was used to simulate the interaction between satellite, sensor probes, booms and surrounding plasma. There are two major contributions in the paper. Firstly the layout of the sensor probes outside the satellite was optimized to reduce the influence of wake effect. Secondly, the fixing mode between the boom and satellite was optimized to reduce the influence of satellite potential change on the probe charging characteristic.

Double-probe spaceborne electric field sensor (DSEFS) was used to detect the ionospheric electric field abnormal of earthquake precursor. The DSEFS is comprised of four probes and four booms outside the satellite and one signal acquisition and processing system inside the satellite. Four cylindric electrodes called C2 of the probes were used to connect the booms and the probes. The length of C2 is one of the most important geometric parameter need to be optimized to ensure the detecting precision of DSEFS. In order to understand the operation of the electric field probes and optimize its performance, Spacecraft Plasma Interaction System (SPIS) software and DEMETER detected data were used to study the influence of C2 length on the DSEFS detection precision. The simulation results showed that when the C2 length is bigger than 2 Debye lengths, the influence of the boom potential had almost no disturbance on the DSEFS probes. In the case of short C2 length, when the boom had a potential which is positive with respect to the probes, the local electric field between the boom and the probe was the dominant factor, the probe collected currents monotonously increased with the increasing of C₂ length. When the boom has a negative potential with respect to the probe, the probe collected current did not monotonously increased with the increasing of C2 length, when the length of C2 is relatively short (less than 20cm), the effect of boom sheath was the dominant factor, the probe collected current increased with the increasing of C2 length; when the length of C2 is larger than 20cm, the local electric field became the dominant factor, the probed colleted current decreased with the increasing of C2 length. The computer simulation result provided good guidance on optimization design of the C2 length of DSEFS.