In Situ Offset Compensation for Intracranial Pressure Sensors

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Solution Overview

Problem

Current pressure sensors for intracranial pressure monitoring face challenges with calibration errors and drift due to water uptake and electronic interference from bodily fluids, leading to inaccurate readings and increased risk of false pressure measurements.

Innovation Solution

A pressure sensor system featuring a deformable membrane with a contiguous energizable membrane that alters sensor readings, allowing for automatic correction of sensor drift and calibration without user input, using a delta response method to determine actual pressure values by applying a controlled voltage across the contiguous membrane.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pressure sensors are calibrated by immersion in saline solution before implantation, then water uptake and mechanical relaxation effects are corrected, but calibration errors and drift due to electronic interference from bodily fluids occur

Engineering Contradiction:
Improvepressure reading accuracyVSAvoidsensor stability in bodily fluids
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by performing calibration measurements in a controlled environment before implantation, establishing baseline sensor characteristics. The system then uses post-implantation energization of the second membrane to compensate for drift effects that occur after deployment, combining pre-preparation with active compensation during operation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by continuously monitoring sensor readings and using the energized second membrane to generate compensatory deflection. The system processes the difference between expected and actual readings, adjusting measurements in real-time to compensate for drift caused by bodily fluid interference and electronic effects.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If manual calibration is performed by personnel in the operating room, then sensor drift is corrected, but handling errors and time consumption increase

Engineering Contradiction:
Improvesensor calibration accuracyVSAvoidsensor preparation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies self-service by enabling the sensor system to perform its own calibration and compensation without requiring manual intervention from personnel. The energized second membrane automatically compensates for drift effects, and the system self-corrects calibration errors through electronic processing of the membrane deflection differences.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical calibration procedures with an electronic/energetic system. Instead of physically immersing the sensor in saline solution for calibration, the system uses electrical energization of the second membrane to create controlled mechanical deflection, substituting manual calibration operations with automated electronic compensation.

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

3Measurement precision

If capacitive or piezoresistive effects are used to measure membrane deflection, then pressure can be detected, but electronic interference with fluids causes drift

Engineering Contradiction:
Improvepressure detection accuracyVSAvoidelectronic interference from bodily fluids
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent uses the second membrane as an intermediary element that mediates between the pressure sensing function and the harmful electronic interference from bodily fluids. By energizing this intermediate membrane, the system creates a compensatory mechanical effect that counteracts the drift caused by direct electronic interference, protecting the primary sensor measurements.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies parameter changes by dynamically altering the mechanical state of the second membrane through electrical energization. This changes the physical parameters of the sensor system (membrane tension, deflection characteristics) to compensate for electronic interference effects, allowing the sensor to maintain accuracy despite environmental factors.

Inventive Principle:
Principle #35Parameter changes

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 approach enables accurate and automatic correction of sensor readings in situ, reducing handling errors and time required for sensor preparation, while providing reliable and precise pressure measurements by compensating for sensor drift and interference effects.

Implementation Method 1

a polarization contact such that an electrostatic force is exerted on the membrane when the actuator is charged

Methodology Applied
Scientific EffectElectrostatic actuation: Electrostatics

Implementation Method 2

The deflection typically is measured using capacitive or piezoresistive effects

Methodology Applied
Scientific EffectPressure-induced deflection: Deformation

Implementation Method 3

The deflection typically is measured using capacitive or piezoresistive effects

Methodology Applied
Scientific EffectCapacitive effect: Capacitance

Implementation Method 4

The deflection typically is measured using capacitive or piezoresistive effects

Methodology Applied
Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentEP2464279B1In situ offset compensation for pressure sensors
Publication Date: 2020.01.01 INTEGRA LIFESCI SWITZERLAND SARL
  • EP2464279B1 patent drawingFigure 1A
  • EP2464279B1 patent drawingFigure 1B
  • EP2464279B1 patent drawingFigure 2A~2C

AI summary

A pressure sensor having a substrate and a first, deformable membrane, partially supported by the substrate, which generates a first sensor reading when deformed by pressure. A second membrane is contiguous to the first membrane. When the second membrane is energized, it deforms the first membrane to alter the first sensor reading. The objective of the invention is to enable automatic correction of sensor readings without input from a user.