Optical Detection of Media in Two Layers with Optical Separation

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Solution Overview

Problem

Existing miniaturized analysis systems for liquid detection in diagnostic applications face challenges in accurate liquid dosing due to the need for precise liquid tracking, which is often hindered by optical separation issues and scattered light, especially when dealing with channels filled with air or inert gases.

Innovation Solution

A method utilizing a microfluidic structure with two optically coupled layers, where a light beam is kept in the first layer by total internal reflection and switched to the second layer when the refractive index changes, allowing for precise liquid detection and bubble identification by deflection of the light beam.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical components are integrated into the analyzer for liquid detection, then measurement capability is improved, but device complexity and cost increase

Engineering Contradiction:
Improveliquid detection accuracyVSAvoidoptical component integration
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies this principle by integrating the optical detection components directly into the disposable insert rather than the analyzer. The insert becomes the optical measurement device with light sources and detectors built-in, eliminating the need for complex integrated optical components in the analyzer while maintaining measurement capability. This reduces device complexity and cost.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If optical separation is used in the measuring area, then liquid tracking is enabled, but scattered light effects increase measurement errors

Engineering Contradiction:
Improveliquid front detection accuracyVSAvoidscattered light influences
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the optical separation function from the measuring area by using a distinct optical separation layer positioned away from the measurement region. This allows liquid tracking through refractive index changes in the channel while eliminating scattered light effects in the measuring area where the light beam actually interacts with the liquid.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the optical path into distinct regions: a first path through the optical separation layer for reference measurements and a second path through the liquid-filled channel for liquid detection. This segmentation allows the harmful scattered light effects to be isolated from the measurement area, improving measurement precision.

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If discrete components are placed at monitoring points for liquid detection, then liquid tracking is achieved, but device complexity increases

Engineering Contradiction:
Improveliquid level detection accuracyVSAvoidcomponent placement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the optical detection components (light sources and detectors) directly into the insert structure at the monitoring points. This integration eliminates the need for separate discrete components placed at each monitoring location, reducing device complexity while maintaining accurate liquid level detection through the optical path.

Inventive Principle:
Principle #5Merging (Combining)

4Measurement precision

If optical fibers are used for measurements, then liquid tracking is enabled, but coupling complexity increases

Engineering Contradiction:
Improveliquid front detection accuracyVSAvoidoptical coupling complexity
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical optical fiber coupling system with a direct optical integration approach. The light sources and detectors are embedded directly in the insert at the monitoring points, eliminating the need for complex optical fiber coupling mechanisms while enabling precise liquid front detection through the integrated optical path.

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

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 precise liquid dosing and detection, minimizing scattered light effects, and allows for flexible integration into disposable inserts, with the ability to detect refractive index changes and generate signals when a liquid front reaches a discrete path section, suitable for diagnostic and lab-on-a-chip applications.

Implementation Method 1

a light beam is kept in the first layer by total internal reflection and switched to the second layer when the refractive index changes

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

the refractive index in the measuring area changes due to the incoming second medium, so that the conditions for total internal reflection are no longer met, and the light beam is directed into the second layer

Methodology Applied
Scientific EffectRefractive index change: Refraction

Data Source

PatentEP2686664B1Flat optical detection of media in at least two layers with optical separation
Publication Date: 2019.04.10 ROBERT BOSCH GMBH
  • EP2686664B1 patent drawingFigure 1~2
  • EP2686664B1 patent drawingFigure 3~4
  • EP2686664B1 patent drawingFigure 5~6

AI summary

The present invention relates to a system for optically detecting liquids, comprising an insert having two contiguous layers (1, 2), wherein the first layer (1) and the second layer (2) are substantially optically separated (4) and are optically coupled only in the measuring region (3), wherein at least one microfluidic structure for conducting liquids is situated in the measuring region (3), wherein a light beam can be injected into the first layer (1) and is held by total internal reflection, and wherein the second layer (2) is transparent to the injected light beam.