Capacitive Microsensor With Compensation Electrode for Stray Capacitance

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Solution Overview

Problem

Capacitive microsensors are susceptible to environmental influences, particularly stray capacitance variations due to foreign material accumulation and changes in dielectric constants, which affect measurement accuracy and sensitivity.

Innovation Solution

Incorporation of a compensation electrode that forms a compensation capacitance connected in series or parallel with the stray capacitance via an electrical terminating circuit to actively or passively compensate for stray capacitance, thereby maintaining measurement accuracy and sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a capacitive microsensor is designed with a membrane and electrodes for measuring environmental variables, then measurement functionality is achieved, but stray capacitance from foreign material accumulation and dielectric constant changes degrades measurement precision

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidstray capacitance

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A compensation electrode is introduced as an intermediary element between the sensor membrane and the external environment. This compensation electrode forms a compensation capacitance that acts as a mediator to counteract the harmful stray capacitance effects, thereby protecting the measurement precision without interfering with the primary sensing function

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful stray capacitance formed by foreign material accumulation into a beneficial compensation mechanism. By strategically positioning the compensation electrode, the stray capacitance is transformed into a useful compensation capacitance that actively counteracts environmental interference, turning a harmful factor into a protective one

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If the sensor element is exposed to the sensor environment for direct measurement, then sensitivity to environmental variables is improved, but stray capacitance variations reduce reliability

Engineering Contradiction:

ImproverobustnessVSAvoidenvironmental influences

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The compensation electrode serves as a protective intermediary that shields the sensor element from direct environmental interference. It forms a compensation capacitance that mediates between the sensor and the environment, allowing the sensor to remain exposed for sensitivity while protecting against stray capacitance variations for reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The compensation electrode effectively reduces the impact of environmental influences, enhancing the robustness and reliability of the microsensor by stabilizing capacitance measurements.

Implementation Method 1

at least one first compensation electrode is arranged between the first terminal region and the first electrode, which compensation electrode, together with the first terminal region, forms a compensation capacitance effective at least over the sensor environment

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

a stray capacitance effective over the sensor environment is formed

Methodology Applied

Scientific EffectStray capacitance: Parasitic Capacitance

Data Source

PatentUS20250297870A1Capacitive microsensor with compensation electrode

Publication Date: 2025.09.25 ROBERT BOSCH GMBH

AI summary

A capacitive microsensor. The capacitive microsensor includes a sensor element having an electrical terminating circuit that provides an input voltage formed between an electrical first input potential and an electrical second input potential and taps at least one electrical first output potential and includes at least one electrical first terminal region facing a sensor environment, further having at least one first capacitance formed by a first electrode facing the sensor environment of the sensor element and a first counter electrode electrically integrated in the terminating circuit, a stray capacitance effective over the sensor environment being formed and at least one first compensation electrode being arranged between the first terminal region and the first electrode, which, together with the first terminal region, forms a compensation capacitance effective over the sensor environment and which is electrically connected to the stray capacitance via the terminating circuit for compensating the stray capacitance.