Automated Peritoneal Dialysis Load Cell Calibration for Fluid Accuracy

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Solution Overview

Problem

Existing automated peritoneal dialysis (APD) systems face issues with pneumatic cassette sealing delays, acoustic noise, and user inconvenience due to manual operation and supply transport, necessitating an improved APD machine design.

Innovation Solution

A peristaltic pump-based APD system with a disposable cassette and user-friendly design, featuring a bag shelf enclosure, color-coded markers, and a control unit that automates fluid management, including efficient drain handling and load cell calibration for accurate fluid monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If pneumatic cassette sealing is used in APD systems, then automated fluid management is achieved, but acoustic noise and sealing delays occur

Engineering Contradiction:

Improveautomated fluid managementVSAvoidacoustic noise

Core Design Contradiction:

Extent of automationVSObject-affected harmful factors

Solution Approach 1:

The patent removes the pneumatic sealing mechanism from the system entirely, replacing it with a manual cassette loading approach. This extraction eliminates the source of acoustic noise while preserving automated fluid management through electronic control of pumping and valve operations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical pneumatic sealing system with an electronic control system that manages fluid flow through electronically controlled valves and pumps. This substitution eliminates mechanical noise while maintaining automated fluid management capabilities.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If manual operation and supply transport are required, then device complexity is reduced, but user convenience and treatment efficiency deteriorate

Engineering Contradiction:

Improvesystem structureVSAvoiduser convenience

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The patent divides the system into a reusable electronic control unit and disposable cassettes containing fluid pathways and reservoirs. This segmentation allows the complex automated control electronics to be separated from the disposable fluid handling components, reducing overall system complexity while maintaining user convenience through automated operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs disposable cassettes that contain the fluid pathways and reservoirs, eliminating the need for complex cleaning and sterilization procedures. This disposable approach simplifies the system structure while significantly improving ease of operation and user convenience.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Device complexity

If load cell calibration is not performed, then device complexity is reduced, but measurement precision of fluid monitoring deteriorates

Engineering Contradiction:

Improvecalibration systemVSAvoidfluid monitoring accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent performs load cell calibration automatically during the initial setup phase before clinical use. This preliminary calibration action ensures measurement precision is established beforehand, eliminating the need for complex ongoing calibration systems while maintaining accurate fluid monitoring throughout treatment.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements self-calibration functionality where the system automatically calibrates its own load cells using built-in reference weights or known fluid volumes. This self-service approach maintains measurement precision without requiring external calibration equipment or complex calibration procedures.

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

The system enhances user experience by reducing noise, simplifying operations, and minimizing manual effort, while ensuring precise fluid delivery and disposal, thus improving treatment efficiency and patient convenience.

Implementation Method 1

peristaltic pump actuator, a disposable set including a peristaltic pump tube

Methodology Applied

Scientific EffectPeristalsis: Peristalsis

Implementation Method 2

load cell calibration for accurate fluid monitoring

Methodology Applied

Scientific EffectLoad cell measurement:

Data Source

PatentUS20250325736A1Automated peritoneal dialysis system having load cell calibration

Publication Date: 2025.10.23 BAXTER INT INC

AI summary

A dialysis machine operable with a disposable set having at least one container, the dialysis machine including a pump actuator operable to pump dialysis fluid to and/or from the at least one container; a weigh plate positioned to support the at least one container; a plurality of operational load cells positioned to support the weigh plate; a linear actuator positioned to apply a force to the weigh plate; a calibration load cell positioned to measure the force applied by the linear actuator; and a control unit in operable communication with the operational load cells, the linear actuator and the calibration load cell, the control unit configured to cause the linear actuator to apply the force to the weigh plate, compare resulting outputs from the operational load cells and the calibration load cell, and determine a calibration factor from the comparison for offsetting future outputs from the operational load cells.