2D Microfluidic Structure for Capacitance Sensing of Individual Particles

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Solution Overview

Problem

Existing techniques for measuring dielectric properties of biological particles in fluid suspensions are limited by their inability to provide detailed, real-time measurements of individual particles, often relying on average values and requiring bulky laboratory equipment.

Innovation Solution

A 2D microfluidic structure with isolated electrodes on two substrates, allowing for capacitance sensing of substances within microfluidic channels, enabling sensitive detection of dielectric properties without direct contact and overcoming limitations of optical imaging and electrode contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical imaging equipment (microscopes, high-speed cameras) is used for particle detection, then visual observation of particles is enabled, but the system becomes large and bulky, confined to laboratory environment, and cannot detect submicron particles below optical diffraction limit

Engineering Contradiction:

Improveparticle detection capabilityVSAvoidsystem size and portability

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces optical imaging systems with an electrical sensing system that uses capacitive electrodes to detect particles. This substitution eliminates the need for microscopes and cameras, enabling a compact, portable device that can detect particles including submicron particles that are below the optical diffraction limit.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from optical properties (which have diffraction limits) to electrical properties (capacitance, impedance). This parameter change allows detection of submicron particles and enables the system to be miniaturized while maintaining or improving detection capability.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If direct contact sensing electrodes are used for electrical detection, then conductivity measurement is enabled, but the electrodes become contaminated by microdroplets, particles, or background fluid, limiting detection of smaller conductivity variations

Engineering Contradiction:

Improveconductivity detection sensitivityVSAvoidelectrode contamination

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a dielectric barrier layer as an intermediary between the sensing electrodes and the sample. This barrier prevents direct contact between the electrodes and conductive samples (microdroplets, particles, background fluid), eliminating contamination while still allowing capacitive coupling for detection. This enables reliable detection of small conductivity variations without electrode degradation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If DEP and ROT methods are used for single cell analysis, then dielectric property measurement is enabled, but measurement speed is slow (multiple seconds per cell) and both crossover frequency measurement and electrorotation spectrum are required

Engineering Contradiction:

Improvedielectric property measurementVSAvoidmeasurement throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent extracts only the essential measurement component by using simple capacitive sensing to directly measure dielectric properties, eliminating the need for complex multi-step procedures like crossover frequency measurement and electrorotation spectrum analysis. This extraction of the core function enables rapid single-cell analysis with high throughput while maintaining measurement precision.

Inventive Principle:

Principle #2Taking out (Extraction)

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 2D microfluidic structure enables precise, real-time capacitance sensing of individual particles, improving detection sensitivity and throughput while avoiding contamination and optical limitations, and is scalable for nanoparticle detection.

Implementation Method 1

2D microfluidic structure for capacitance sensing of one or more substances of interest

Methodology Applied

Scientific EffectCapacitance sensing: Capacitance

Implementation Method 2

measure the dielectric properties of one or more analysts

Methodology Applied

Scientific EffectDielectric properties measurement: Dielectric Permittivity

Data Source

PatentUS12270777B22D microfluidic structure

Publication Date: 2025.04.08 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A 2D microfluidic structure for capacitance sensing of analyte is provided. The structure includes a first substrate located above at least one microfluidic channel, and a second substrate located below the at least one microfluidic channel. The first substrate includes at least one first group of three isolated electrodes and the second substrate includes at least one second group of three isolated electrodes, where each group of isolated electrodes includes a ground electrode and two probe electrodes.