Capacitive Electrode Network for Microplate Level Detection

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Solution Overview

Problem

Current laboratory devices face challenges in accurately and reliably determining the filling status of multiple closely spaced containers, particularly in complex laboratory systems, due to issues like mechanical and technical problems, crosstalk, and insufficient resolution in existing capacitive and ultrasound-based methods.

Innovation Solution

A capacitive network of electrodes is used, where electrodes can be arranged on or integrated into containers, and their configuration allows for non-contact level measurement, adapting to various conditions by adjusting voltage potentials and minimizing parasitic capacitances, enabling precise detection of liquid levels in closely spaced containers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electrodes are arranged on the back of microplates for non-contact level measurement, then measurement accuracy and resolution are improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improveliquid level detection accuracyVSAvoidelectrode arrangement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The microplate is divided into multiple measurement channels, each with dedicated transmitting and receiving electrodes. This segmentation allows independent optimization of each measurement channel while maintaining overall system integration, resolving the contradiction between measurement precision and device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The electrode structure is nested within the microplate design, with transmitting and receiving electrodes integrated into the microplate's structural elements. This nesting approach enables non-contact measurement while minimizing the additional complexity of separate electrode assemblies.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Productivity

If high spatial density of components is used to achieve high integration, then productivity and automation are improved, but crosstalk between neighboring measuring channels increases

Engineering Contradiction:
Improvemeasurement speedVSAvoidcrosstalk between channels
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The electrode design incorporates local quality variations, with specific geometric configurations and spacing optimized for each measurement channel. This local optimization minimizes crosstalk between adjacent channels while maintaining high spatial density and measurement speed.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent utilizes the electric field interactions between adjacent electrodes, which would normally cause crosstalk, by designing the electrode geometry and signal processing to convert these interactions into useful measurement information. This approach turns the harmful crosstalk effect into a beneficial feature for improved measurement accuracy.

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

3Ease of operation

If ultrasound methods are used for level detection, then non-contact measurement is achieved, but measurement resolution and precision are insufficient

Engineering Contradiction:
Improvenon-contact measurement capabilityVSAvoidliquid level resolution
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces the mechanical/acoustic ultrasound measurement system with an electrical capacitive sensing system. This substitution maintains non-contact measurement capability while achieving superior resolution through electrical field interactions, resolving the contradiction between ease of operation and measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If existing capacitive methods with parallel electrode plates are used, then level measurement is achieved, but manufacturing complexity and cost increase for high-volume applications

Engineering Contradiction:
Improvelevel measurement capabilityVSAvoidmanufacturing cost for high-volume
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The electrode structure is designed with multi-functionality, serving both as the capacitive sensing elements and as structural support elements of the microplate. This universality reduces the number of separate components needed, simplifying manufacturing for high-volume applications while maintaining measurement precision.

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

The solution provides reliable, accurate, and high-resolution liquid level detection in multiple containers, reducing manual intervention and integration complexity, with improved sensitivity and speed compared to previous methods, achieving a resolution of approximately 1 µl and enabling real-time monitoring.

Implementation Method 1

Capacitive sensors are sometimes used to measure physical variables such as pressure, filling level, volume or relative permittivity. These sensors detect a change in the capacitance of an individual capacitor or an entire capacitor network that occurs in response to a physical quantity to be measured.

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

Capacitive sensors are sometimes used to measure physical variables such as pressure, filling level, volume or relative permittivity.

Methodology Applied
Scientific EffectDielectric permittivity: Dielectric Permittivity

Data Source

PatentEP2371454B1Capacitative measuring method and device for detecting fill levels and laboratory device with same
Publication Date: 2019.11.20 TECAN TRADING AG
  • EP2371454B1 patent drawingFigure 1~2A
  • EP2371454B1 patent drawingFigure 2B~2C
  • EP2371454B1 patent drawingFigure 2D~2E

AI summary

The device (100) has a horizontal base plate (200) comprising electrodes (201.1-201.3) projected in a direction with respect to a horizontal plane. The electrodes are oppositely arranged at an equal distance to each other such that operating zones with equal dimensions are provided. Connectors (202) connect two parts of the electrodes with a transmission circuit (57) and a receiver circuit (58), respectively. Each electrode is present in a region of each operating zone in the horizontal plane. The electrodes are utilized as a transmitter and a receiver by the connectors, respectively. An independent claim is also included for a capacitive measuring method for capacitive determination of filling level in a container.