Therapeutic Fluid Preparation Device Sensor Calibration

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Solution Overview

Problem

Existing dialysate preparation devices require calibration of conductivity and temperature sensors, which increases the burden on healthcare workers and costs due to disposable sensors, and introduces complexity in manufacturing and hygiene concerns.

Innovation Solution

A therapeutic fluid preparation device that uses an electrolyte with known conductivity and temperature to calibrate sensors, improving measurement accuracy without additional functions or increased burden, by supplying the electrolyte through the mixing circuit and using the sensors to measure and calibrate based on a correlation between temperature and conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If sensors are calibrated by separately attaching a standard sensor to the circuit, then measurement accuracy is improved, but the burden on healthcare workers and hygiene risks increase

Engineering Contradiction:
Improveconcentration measurement accuracyVSAvoidoperation burden on healthcare workers
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system performs self-calibration by using the electrolyte supply means to automatically introduce a calibration solution through the mixing circuit, eliminating the need for healthcare workers to manually attach standard sensors. The control unit automatically controls the calibration process based on concentration information of the electrolyte.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The calibration is performed in advance by preparing the electrolyte with known concentration information before the actual blood treatment process begins. This preliminary calibration ensures measurement accuracy is established before clinical use, reducing operational burden during treatment.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If calibration is performed by manufacturing sensors with calibration functions, then measurement accuracy is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvesensor measurement accuracyVSAvoidsensor structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The calibration function is extracted from the sensor itself and relocated to the external calibration system consisting of the electrolyte supply means and control unit. This separates the measurement function from the calibration function, keeping the sensor structure simple while achieving accurate measurements through external calibration.

Inventive Principle:
Principle #2Taking out (Extraction)

3Object-affected harmful factors

If disposable sensors are used in a disposable mixing circuit, then hygiene is improved, but cost increases due to repeated calibration needs

Engineering Contradiction:
Improvehygiene risk reductionVSAvoidcost of disposable components
Core Design Contradiction:
Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The disposable mixing circuit performs self-calibration using the integrated electrolyte supply means, eliminating the need for external calibration services or repeated sensor replacements. This reduces the overall cost of disposable components while maintaining hygiene standards.

Inventive Principle:
Principle #25Self-service

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

Enhances measurement accuracy of concentration in therapeutic fluid preparation without increasing the burden on healthcare workers or adding functions to sensors, reducing costs and complexity in calibration and manufacturing.

Implementation Method 1

a concentration measuring device having an electric conductivity sensor configured to measure the electric conductivity of the solution mixture in the mixing circuit

Methodology Applied
Scientific EffectElectric conductivity measurement: Conduction (electrical)

Implementation Method 2

a temperature sensor configured to measure the temperature of the solution mixture in the mixing circuit

Methodology Applied
Scientific EffectTemperature measurement: Thermocouple

Implementation Method 3

to calibrate the electric conductivity sensor based on the difference between the measured temperature and a known temperature of the electrolyte by referring to a correlation between temperature and electric conductivity

Methodology Applied
Scientific EffectTemperature-conductivity correlation:

Data Source

PatentEP3498315B1Therapeutic fluid preparation device and blood processing system
Publication Date: 2020.07.15 ASAHI KASEI MEDICAL CO LTD
  • EP3498315B1 patent drawingFigure 1
  • EP3498315B1 patent drawingFigure 2
  • EP3498315B1 patent drawingFigure 3

AI summary

An object of the present application is to improve the measurement accuracy of a concentration measuring device of a therapeutic fluid preparation device, without increasing the burden to healthcare workers during a preparation stage for treatment, such as continuous treatment, and without the need to add further functions to a sensor. The invention relates to a therapeutic fluid preparation device for preparing therapeutic fluid having a predetermined concentration by mixing a plurality of stock solutions, the device comprising: a mixing circuit in which the plurality of stock solutions are mixed; a concentration measuring device having an electric conductivity sensor that measures an electric conductivity of a solution mixture in the mixing circuit and a temperature sensor that measures a temperature of the solution mixture, the concentration measuring device measuring a concentration of the solution mixture in accordance with the measured electric conductivity by the electric conductivity sensor and the measured temperature by the temperature sensor; electrolyte supply means that supplies an electrolyte having a known concentration through the mixing circuit; and calibration means that directs the electrolyte supply means to supply the electrolyte having the known concentration through the mixing circuit, that measures a temperature of the supplied electrolyte using the temperature sensor, and that calibrates the electric conductivity sensor based on the difference between the measured temperature and a known temperature of the electrolyte by referring to a correlation between temperature and electric conductivity.