Recessed Electrodes for Ophthalmic Flow Sensing

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Solution Overview

Problem

Existing surgical pump systems, particularly vacuum-based systems, face challenges in accurately measuring aspiration flow rates due to varying pressure differentials, viscosity changes, and occlusion conditions, making direct flow measurement impractical.

Innovation Solution

A flow sensor system with an electrode terminal chamber and Hall-effect electromagnetic flow meter is introduced, featuring electrode terminals positioned to avoid contact with viscoelastic materials, using a magnetic field to induce a voltage across conductive fluids, and a tapered outlet to direct flow through the center of the chamber, minimizing noise and ensuring accurate flow measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electrode terminals are positioned close to the flow channel for sensitive detection, then measurement precision is improved, but viscoelastic materials may contact the electrodes causing noise and measurement errors

Engineering Contradiction:

Improveflow rate measurement precisionVSAvoidnoise from viscoelastic material contact

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The electrode terminal chamber is designed with non-uniform geometry, specifically a tapered outlet end that creates a center portion with different flow characteristics. This local geometric variation directs viscoelastic materials away from the electrode terminals while maintaining close proximity for sensitive detection, resolving the contradiction between measurement precision and noise avoidance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent positions electrode terminals in a specific spatial arrangement within the chamber, utilizing the third dimension (depth/distance from flow channel) to separate electrodes from viscoelastic material contact paths. The terminals are disposed at a distance from the flow channel that prevents material impingement while maintaining detection capability through the conductive fluid path

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If a vacuum-based system is used for aspiration, then system complexity is reduced compared to positive displacement systems, but direct flow measurement becomes impractical due to varying pressure differentials and viscosity changes

Engineering Contradiction:

Improvepump system complexityVSAvoidflow rate measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical flow measurement methods (which would be complex in vacuum systems) with an electromagnetic sensing approach using conductive fluid detection. This substitution enables direct flow measurement in vacuum-based systems by detecting the presence and movement of conductive irrigation fluid through electrode terminals, overcoming the limitations of pressure differential variations and viscosity changes

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Stability of the object's composition

If the outlet end is designed with a taper to smooth flow, then flow uniformity is improved, but the chamber geometry becomes more complex

Engineering Contradiction:

Improveflow uniformityVSAvoidchamber geometry complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The outlet end of the electrode terminal chamber is designed with a tapered geometry that creates smooth curved transitions in the flow path. This curvature design promotes uniform flow distribution and directs viscoelastic materials away from electrode terminals, achieving flow stability with a relatively simple geometric modification rather than complex internal structures

Inventive Principle:

Principle #14Spheroidality (Curvature)

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

Enables precise and reliable aspiration flow rate control, allowing for the emulation of flow-based pump systems using vacuum-based systems, improving operational safety and efficiency by providing a low-cost, direct measurement solution.

Implementation Method 1

Methodology Applied

Scientific EffectHall-effect electromagnetic induction: Hall Effect

Data Source

PatentUS7837660B2Recessed electrodes for sensing flow in ophthalmic surgical system

Publication Date: 2010.11.23 BAUSCH & LOMB INC

AI summary

A flow measurement device 100 is provided that includes an electrode terminal chamber 102 with an inlet 104 in communication with a flow channel 108 for receiving fluid and viscoelastic material aspirated from a surgical site, and an outlet 106 that tapers into a flow channel 108. The outlet 108 has a taper angle that is sufficient to smooth flow and cause viscoelastic material entering the electrode terminal chamber 102 to flow substantially within a center portion of the chamber and through the outlet 106. The electrode terminal chamber 102 further includes first and second electrode terminals 130 and 140 disposed on generally opposite sides of the electrode terminal chamber 102 in a spaced-apart manner. The first and second electrode terminals 130 and 140 are positioned a distance from the center of the chamber 102 that is sufficient to substantially avoid contact between the terminals and viscoelastic materials flowing through the chamber 102.