Capacitive Sensor for Electron Microscope Position Measurement

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current positional sensors in electron microscopes face challenges in accurately measuring both lateral displacement and rotational orientation over a limited range, especially in environments susceptible to magnetic interference, and often require synchronization with periodic markers, which can disrupt experiments.

Innovation Solution

A capacitive sensor system utilizing opposing sets of capacitor plates with rotational symmetry, where moving and stationary plates measure changes in capacitance to calculate both angular and lateral displacement, allowing for precise position measurement within a single sensor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical encoders are used to measure position, then measurement precision can reach a few nm, but the measurement range is limited by the periodicity of the ruler (a few um) and requires synchronization counters that can get out of sync

Engineering Contradiction:

Improveposition measurement precisionVSAvoidmeasurement continuity and synchronization reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical/optical encoder system with a capacitive sensing system. Instead of using a physical ruler with periodic markings and optical detection, the invention uses capacitive coupling between moving and stationary plates to directly measure displacement. This substitution eliminates the periodicity limitation and synchronization requirements while maintaining high measurement precision through continuous capacitive coupling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces capacitive coupling as an intermediary measurement mechanism. Rather than directly reading positional markings, the system uses the change in capacitance between moving and stationary plates as an intermediary signal that continuously reflects displacement without requiring synchronization or periodic reference marks.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If magnetic field-based techniques are used to measure position, then measurement capability is provided, but the sensor is susceptible to interference from stray magnetic fields or influences the microscope performance

Engineering Contradiction:

Improveposition measurement capabilityVSAvoidmagnetic field interference and stray field influence

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces magnetic field-based measurement techniques with a capacitive sensing system. By using electrical capacitance between plates instead of magnetic fields, the invention eliminates susceptibility to magnetic interference and prevents the sensor from influencing the electron microscope's magnetic environment, while maintaining position measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If a single sensor measures both lateral and rotational displacement, then device complexity is reduced, but measurement precision for both parameters simultaneously is challenging

Engineering Contradiction:

Improvesensor system complexityVSAvoidsimultaneous angular and lateral displacement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent designs a universal capacitive sensor system where the same set of moving and stationary plates serves multiple measurement functions. By strategically positioning and configuring the plates, the system can simultaneously measure both lateral displacement (through overall capacitance changes) and rotational displacement (through differential capacitance changes between opposite plates), reducing device complexity while maintaining precision for both parameters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 and continuous measurement of both lateral and rotational displacement without synchronization issues, maintaining precision and avoiding interference from stray magnetic fields, thus enhancing the operational reliability of electron microscopes.

Implementation Method 1

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS8704536B2Lateral displacement and rotational displacement sensor

Publication Date: 2014.04.22 RGT UNIV OF CALIFORNIA

AI summary

A position measuring sensor formed from opposing sets of capacitor plates measures both rotational displacement and lateral displacement from the changes in capacitances as overlapping areas of capacitors change. Capacitances are measured by a measuring circuit. The measured capacitances are provided to a calculating circuit that performs calculations to obtain angular and lateral displacement from the capacitances measured by the measuring circuit.