Phacoemulsifier Actuator Resonance Tracking

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Solution Overview

Problem

In phacoemulsification surgery, existing technologies face challenges in efficiently determining and maintaining the mechanical resonant frequency of the piezoelectric actuator and its coupled needle to achieve maximum vibration amplitude for effective emulsification of the cataract lens, as the mechanical and electrical resonant frequencies differ and are influenced by varying mechanical and electrical parameters.

Innovation Solution

The solution involves determining the mechanical resonant frequency by measuring the electrical power input metric, which is maximized at a specific frequency, and using a processor to drive the actuator at this frequency, ensuring the actuator and needle operate in mechanical resonance, even with fluid present, by adjusting the phase factor and iteratively adjusting the driving frequency to maximize power delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the actuator is driven at electrical resonant frequency, then the electrical power input is maximized, but the mechanical vibration amplitude is not maximized because mechanical and electrical resonant frequencies differ

Engineering Contradiction:

Improveelectrical power inputVSAvoidmechanical vibration amplitude

Core Design Contradiction:

PowerVSStrength

Solution Approach 1:

The patent replaces direct mechanical frequency measurement with an electrical measurement system. By monitoring electrical power input, current, and voltage phase relationships, the system indirectly determines mechanical resonant frequency conditions without requiring direct mechanical sensors on the needle assembly.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system continuously monitors electrical parameters (power input, current, voltage phase) and uses this feedback to adjust the driving frequency. When the electrical power metric reaches its maximum, the system identifies this as the mechanical resonant frequency and maintains operation at this point, creating a closed-loop control system.

Inventive Principle:

Principle #23Feedback

2Productivity

If the driving frequency is adjusted to maximize mechanical vibration amplitude, then emulsification efficiency is improved, but the complexity of frequency determination and control increases

Engineering Contradiction:

Improveemulsification efficiencyVSAvoidfrequency determination and control complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system uses its own electrical power consumption characteristics to determine the optimal operating frequency. By monitoring when electrical power input reaches its maximum, the system self-identifies the mechanical resonant frequency without requiring external calibration equipment or complex measurement systems.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the approach from directly measuring mechanical parameters (frequency, amplitude) to monitoring electrical parameters (power input, current, voltage phase). This parameter substitution simplifies the control system by using readily available electrical measurements instead of requiring complex mechanical sensing.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the needle contacts the eye lens, then emulsification function is achieved, but the mechanical resonant frequency shifts substantially from the electrical resonant frequency

Engineering Contradiction:

Improveemulsification functionVSAvoidfrequency accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system dynamically adjusts the driving frequency based on real-time electrical power measurements. As the mechanical load changes when the needle contacts the lens, the electrical resonant frequency shifts, and the system continuously tracks this change by monitoring when electrical power input is maximized, maintaining accurate frequency control throughout the procedure.

Inventive Principle:

Principle #15Dynamics

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 ensures the needle vibrates at its maximum amplitude, enhancing the efficiency of cataract emulsification by accurately identifying and maintaining the mechanical resonant frequency, thereby improving the phacoemulsification process.

Implementation Method 1

a phacoemulsification probe (12), comprising a piezoelectric actuator (22) coupled with a needle (16)

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the combination of the actuator and its coupled needle should be operated at its mechanical resonant frequency

Methodology Applied

Scientific EffectMechanical resonance: Resonance

Data Source

PatentUS20230338190A1Driving a phacoemulsifier actuator

Publication Date: 2023.10.26 JOHNSON & JOHNSON SURGICAL VISION INC

AI summary

Methods and apparatuses provide a phacoemulsification probe, wherein the probe has a piezoelectric actuator coupled with a needle configured to be inserted into an eye of a patient; and a processor configured to sequentially drive the actuator electrically in a range of frequencies, to measure a respective electrical power input to the actuator at each of the frequencies in the range, to identify a frequency in the range of frequencies wherein a metric of the electrical power input is a maximum, and to estimate from the identified frequency a mechanical resonant frequency of the actuator, and to drive the actuator electrically at the mechanical resonant frequency.