Eddy Current Pressure Sensor for Ophthalmic Fluidics
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Solution Overview
Problem
Existing systems for monitoring fluid pressure during ophthalmic surgery face limitations, including limited frequency response and high hysteresis with load cell sensors and sensitivity to optical alignment with optical sensors, necessitating improved methods for accurate and reliable pressure measurement.
Innovation Solution
The implementation of an eddy current pressure sensor system using a conductive, movable diaphragm with a non-contact position sensor coil that senses inductance or impedance variations to correlate fluid pressure changes, providing a non-invasive and non-contact measurement method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a load cell is used to measure diaphragm deflection, then pressure measurement is achieved, but the frequency response is limited and hysteresis is high
Solution Approach 1:
The patent replaces the mechanical load cell system with an electromagnetic eddy current sensor system. The eddy current sensor uses electromagnetic fields to detect diaphragm position without mechanical contact, eliminating the mechanical limitations of load cells and achieving both high-frequency response and high measurement precision.
Solution Approach 2:
The patent introduces a conductive diaphragm as an intermediary between the fluid pressure and the eddy current sensor. The diaphragm converts pressure changes into positional changes that can be detected by the electromagnetic sensor, enabling indirect but high-fidelity pressure measurement without mechanical contact between the sensor and diaphragm.
2Measurement precision
If a load cell is used to measure diaphragm deflection, then pressure measurement is achieved, but hysteresis is high
Solution Approach 1:
The patent replaces the mechanical load cell system with an electromagnetic eddy current sensor system. The eddy current sensor uses electromagnetic fields to detect diaphragm position without mechanical contact, eliminating the mechanical limitations of load cells and achieving both high-frequency response and high measurement precision.
3Measurement precision
If an optical sensor is used to measure diaphragm deflection, then non-contact measurement is achieved, but the system is sensitive to optical alignment and surface finish variations
Solution Approach 1:
The patent replaces the optical measurement system with an electromagnetic eddy current sensor system. The eddy current sensor uses electromagnetic fields rather than optical fields to detect diaphragm position, eliminating sensitivity to optical alignment and surface finish variations while maintaining non-contact measurement capabilities.
Solution Approach 2:
The patent changes the measurement parameter from optical reflection properties to electromagnetic inductance properties. By measuring inductance changes in the eddy current sensor coil rather than optical properties, the system becomes insensitive to surface finish variations and optical alignment issues.
4Ease of operation
If a non-contact sensor is used to measure diaphragm deflection, then no direct contact is required, but the sensor may require additional protection to satisfy safety requirements
Solution Approach 1:
The patent introduces a conductive diaphragm as an intermediary between the fluid pressure and the eddy current sensor. The diaphragm serves as both the measurement target and a safety barrier, allowing non-contact measurement while inherently satisfying safety requirements through its conductive, fluid-tight construction.
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 offers a faster response, reduced hysteresis, and improved accuracy in fluid pressure measurement, overcoming the drawbacks of previous technologies while being compact and simple to operate, with no need for complex optical alignments or direct contact with the diaphragm.
Implementation Method 1
an eddy current position sensor positioned on the second side of the diaphragm without contacting the diaphragm, the eddy current position sensor comprising a position sensor coil activatable by high frequency alternating current and signal conditioning electronics capable of sensing inductance or impedance variation or a resonant frequency change in the position sensor coil as a gap between the diaphragm and the position sensor coil changes
Implementation Method 2
a position sensor coil activatable by high frequency alternating current and signal conditioning electronics capable of sensing inductance or impedance variation or a resonant frequency change in the position sensor coil as a gap between the diaphragm and the position sensor coil changes
Data Source
AI summary
Systems and methods are disclosed for measuring fluid pressure in an ophthalmic surgical system. An example system comprises a fluid flow path and a pressure sensor system for measuring pressure in the fluid flow path. The pressure sensor system comprises a conductive, movable diaphragm having a first side and a second side, the first side of the diaphragm facing the fluid flow path, and an eddy current position sensor positioned on the second side of the diaphragm without contacting the diaphragm. The eddy current position sensor comprises a position sensor coil activatable by high frequency alternating current and signal conditioning electronics capable of sensing inductance or impedance or resonant frequency variation in the position sensor coil as a gap between the diaphragm and the position sensor coil changes and of translating that variation into a displacement signal correlated to fluid pressure. A method of measuring fluid pressure may be performed using one or more of the systems described herein.