Pressure Sensor Negative Pressure Detection

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Solution Overview

Problem

Existing medical fluid pressure sensors struggle to accurately measure negative pressures due to issues with air-tight seals and active vacuum sources, leading to decoupling and inaccurate readings, and require regular testing to ensure detection of negative pressures, which disrupts treatments and increases costs.

Innovation Solution

The use of displacement devices or offset devices, such as air pillows, discs, or springs, that apply a positive force to the pressure sensor, allowing for accurate detection of negative pressures without relying on air-tight seals or active vacuum sources, ensuring consistent contact and reducing the need for regular calibration and treatment interruptions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If air-tight seals and active vacuum sources are used to ensure contact between diaphragm and pressure sensor, then measurement reliability is improved, but device complexity and cost increase

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the complex active vacuum source and air-tight seal system from the pressure sensor assembly. Instead, it relies on the natural elastic rebound of the diaphragm to maintain contact, thereby extracting the unnecessary complex components while preserving the essential measurement function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The diaphragm is designed to automatically rebound to contact the pressure sensor on its own using its elastic properties, without requiring external vacuum sources or complex sealing mechanisms. This self-service mechanism simplifies the system while ensuring reliable measurement.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If active vacuum sources are used to maintain diaphragm contact, then negative pressure detection accuracy is improved, but cost and device complexity increase

Engineering Contradiction:
Improvenegative pressure detection accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the active vacuum source from the system, replacing it with a passive elastic rebound mechanism that achieves the same contact maintenance function without requiring complex vacuum generation equipment.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical vacuum source system with a simpler elastic mechanical rebound mechanism, where the diaphragm's own elasticity provides the necessary contact force, substituting a complex mechanical system with a simpler one.

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

3Reliability

If regular testing and calibration are performed to ensure negative pressure detection, then measurement reliability is improved, but treatment time is reduced due to interruptions

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidtreatment time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements preliminary design features during manufacturing - specifically, the diaphragm's elastic properties are pre-configured to ensure reliable contact and measurement. This preliminary action eliminates the need for repeated calibration and testing during treatment, as the system is designed to be inherently reliable from the start.

Inventive Principle:
Principle #10Preliminary action

4Measurement precision

If air-tight seals are used to prevent debris interference, then measurement accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent removes the air-tight seal component entirely, relying instead on the diaphragm's elastic rebound to maintain contact. This extraction eliminates the seal-related complexity while the open design allows debris to be managed through the natural mechanical action of the diaphragm.

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

This solution enables reliable measurement of negative fluid pressures, reduces treatment disruptions, and lowers the cost of pressure sensor systems by eliminating the need for active vacuum sources, while maintaining accurate pressure readings even with debris present between the diaphragm and pressure transducer.

Implementation Method 1

a diaphragm... configured to contact the pressure sensor and apply a pre-load pressure to the pressure sensor

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3204065B1Sensing negative pressure with a pressure transducer
Publication Date: 2021.12.01 FRESENIUS MEDICAL CARE HOLDINGS INC
  • EP3204065B1 patent drawingFigure 1
  • EP3204065B1 patent drawingFigure 2
  • EP3204065B1 patent drawingFigure 3

AI summary

A medical system includes a medical fluid pumping machine comprising a pressure sensor, a medical fluid line set comprising a fluid line in fluid communication with a fluid passage formed between a diaphragm and a base, the medical fluid line set being configured to be connected to the medical fluid pumping machine in a manner such that the diaphragm of the medical fluid line set aligns with the pressure sensor of the medical fluid pumping machine, and a member configured to apply a positive force to the pressure sensor when the medical fluid line set is connected to the medical fluid pumping machine and the fluid passage is at atmospheric pressure.