Capacitive Sensor for Electrostatic Potential Measurement
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Solution Overview
Problem
Conventional methods for measuring ambient electric fields and surface potentials are cumbersome, expensive, and generate mechanical and electromagnetic noise due to the use of mechanical choppers and require high-impedance sensors that are not suitable for measuring electrostatic fields effectively.
Innovation Solution
A system comprising a pair of metal plates with a non-linear permittivity dielectric material between them, where the capacitance changes with bias voltage, allowing for the detection of electric fields and surface potentials without mechanical chopping, using a simple and inexpensive capacitive sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical choppers with metallic vanes are used to measure ambient electric fields, then the near infinite impedance of the direct current field is converted to a finite impedance, but mechanical and electromagnetic noise is created and a fair amount of power is consumed
Solution Approach 1:
The patent replaces the mechanical chopper system with a solid-state field effect transistor (FET) switch. The FET electronically switches the connection between the sensor and amplifier, eliminating all moving mechanical parts while achieving the same impedance conversion function. This substitution eliminates mechanical noise, electromagnetic noise from rotating vanes, and power consumption associated with mechanical actuators.
Solution Approach 2:
The patent changes the operating parameters by using a FET to dynamically control the impedance state rather than mechanically altering the field. The high input impedance of the FET when off and low impedance when on provides the necessary switching action, changing the operational mode from mechanical to electronic parameter control.
2Measurement precision
If mechanical choppers are used to measure ambient electric fields, then impedance conversion is achieved, but the device complexity increases due to motors and moving vanes
Solution Approach 1:
The patent replaces the mechanical chopper system with a solid-state field effect transistor (FET) switch. The FET electronically switches the connection between the sensor and amplifier, eliminating all moving mechanical parts while achieving the same impedance conversion function. This substitution eliminates mechanical noise, electromagnetic noise from rotating vanes, and power consumption associated with mechanical actuators.
3Measurement precision
If conventional optical sensors are used to measure ambient electric fields, then field measurement is achieved, but the sensor cost is high and the device is cumbersome to use
Solution Approach 1:
The patent employs inexpensive, readily available components including a simple metal plate sensor, a standard field effect transistor, and a basic operational amplifier. These components are far cheaper than specialized optical sensors while providing sufficient measurement capability for electrostatic fields, making the device affordable and easy to manufacture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate measurement of ambient electric fields and surface potentials with minimal noise, power consumption, and cost, using a small capacitive sensor that can be charged by ambient ions, eliminating the need for mechanical choppers and loading currents.
Implementation Method 1
a non-linear permittivity dielectric material disposed between the first metal layer and the second metal layer
Implementation Method 2
a first metal layer, a second metal layer and a non-linear permittivity dielectric material disposed between the first metal layer and the second metal layer
Data Source
AI summary
An electric field detecting system is provided that comprises a first metal plate, a second metal plate, a sensor and a detector. The sensor has a first metal layer, a second metal layer and a non-linear permittivity dielectric material disposed between the first metal layer and the second metal layer. The first metal layer is electrically connected to the first metal plate, whereas the second metal layer is electrically connected to the second metal plate. The detector can detect a voltage between the first metal layer and the second metal layer and can determine a magnitude of the electric field based on the detected voltage and a priori information related to a variable capacitance of the non-linear permittivity dielectric material.