Extracorporeal Blood Reservoir Surface Detection Using Pixel Continuity

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Solution Overview

Problem

Existing liquid surface detection methods in blood reservoirs, such as electrostatic capacitance and ultrasound schemes, fail to reliably detect continuous changes in the blood surface due to blood adherence on the inner wall and interference from filter members, leading to inaccurate blood volume management during extracorporeal circulation.

Innovation Solution

An extracorporeal circulation apparatus with a presence information acquisition unit, such as an imaging unit or temperature detection unit, determines the blood surface position based on consecutiveness of presence information along parallel and perpendicular directions, using color or temperature data to filter out noise and accurately detect the blood surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If light transmission imaging is used to detect blood surface position, then continuous change detection is improved, but noise from adhered blood on inner wall causes unreliable detection

Engineering Contradiction:
Improveblood surface position detection accuracyVSAvoidnoise from adhered blood
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The detection area is divided into multiple pixel regions, and blood presence is determined by checking consecutiveness of blood detection results across adjacent pixels. This segmentation approach allows the system to distinguish between scattered noise from adhered blood and the continuous blood surface, thereby resolving the contradiction between continuous detection capability and noise interference.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from single-point or single-line detection to two-dimensional pixel array detection. By acquiring presence information across multiple pixels in parallel and analyzing spatial consecutiveness, the system can differentiate between random noise (non-consecutive) and actual blood surface (consecutive), thus improving measurement precision while filtering out harmful noise factors.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If conventional liquid surface detection methods are used, then simple implementation is maintained, but they cannot detect continuous changes in blood surface position

Engineering Contradiction:
Improvecontinuous blood surface change detectionVSAvoiddetection system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention replaces conventional mechanical or point-based detection methods with an optical imaging system that captures two-dimensional presence information. The control unit processes this visual data by analyzing consecutiveness patterns across pixels, enabling continuous blood surface monitoring without complex mechanical moving parts, thus achieving high measurement precision with manageable system complexity.

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

Solution Approach 2:

The imaging unit creates a visual copy (image) of the blood surface position, which is then processed by the control unit to determine actual position. This copying approach allows continuous monitoring of blood surface changes without direct physical contact or complex mechanical detection mechanisms, resolving the contradiction between detection capability and system complexity.

Inventive Principle:
Principle #26Copying

3Reliability

If blood volume management is strictly controlled, then patient safety is improved, but inaccurate detection leads to false negatives and improper management

Engineering Contradiction:
Improveblood volume management reliabilityVSAvoidblood surface position detection accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The control unit continuously monitors the consecutiveness pattern of blood presence information from multiple pixels and uses this feedback to accurately determine blood surface position. This continuous feedback mechanism ensures reliable blood volume management by providing precise, real-time detection data, eliminating false negatives that would occur with less accurate detection methods.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection across multiple pixel points before determining the final blood surface position. By预先 checking the consecutiveness pattern across the pixel array, the system ensures accurate detection before making blood volume management decisions, thereby improving reliability and preventing false negatives in critical blood volume assessments.

Inventive Principle:
Principle #10Preliminary action

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 reliable detection of blood surface position, managing blood volume effectively and preventing false negatives by filtering out adherence and filter member interference, thus supporting health care workers in maintaining optimal blood levels.

Implementation Method 1

light emitted from a light source is transmitted through a container including the sample solution. The light transmitted through the container including the sample solution is converted into an electric signal by the imaging device

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

a temperature detection unit, attached to a wall surface of the blood reservoir, detects the temperature of the wall surface along at least one of the first direction and the second direction

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentEP3586890B1Extracorporeal circulation device
Publication Date: 2025.08.20 TERUMO KK
  • EP3586890B1 patent drawingFigure 1
  • EP3586890B1 patent drawingFigure 2
  • EP3586890B1 patent drawingFigure 3

AI summary

[Problem] To provide an extracorporeal circulation apparatus capable of reliably detecting a position of a liquid surface (blood surface) stored in a blood reservoir. [Means for Resolution] An extracorporeal circulation apparatus 2 includes a blood reservoir 3 in which blood is temporarily stored, a presence information acquisition unit 9 that acquires pieces of presence information on blood 21 stored in the blood reservoir 3, and a control unit 7 that executes control to determine the position of a blood surface 22 on the basis of presence or absence of consecutiveness between pieces of the presence information acquired along at least one of a first direction parallel to the blood surface 22 of the blood 21 stored in the blood reservoir 3 and a second direction perpendicular to the blood surface 22 among pieces of the presence information transmitted from the presence information acquisition unit 9.