Phacoemulsification Probe Resonant Frequency Control
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Solution Overview
Problem
Current phacoemulsification probes face challenges in maintaining optimal needle stroke amplitude and minimizing temperature rise during cataract surgery, leading to potential eye damage due to inadequate resonant frequency control and inefficient irrigation/aspiration processes.
Innovation Solution
A phacoemulsification apparatus with a piezoelectric actuator driven by a signal generator, phase detection circuitry, and a controller that adjusts the drive signal frequency to minimize phase difference between voltage and current, ensuring the actuator vibrates at its resonant frequency, thereby maximizing stroke amplitude while minimizing temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the piezoelectric actuator is driven at high power to maximize needle stroke amplitude, then the surgical effectiveness is improved, but the temperature rise increases causing potential eye damage
Solution Approach 1:
The patent utilizes ultrasonic vibration of the piezoelectric actuator to create mechanical oscillations at resonant frequency, which maximizes needle stroke amplitude while improving energy efficiency. The resonant oscillation allows the system to achieve high amplitude with lower input power, thereby reducing heat generation and temperature rise during phacoemulsification surgery.
Solution Approach 2:
The patent dynamically adjusts the drive frequency parameter to track and maintain the resonant frequency of the piezoelectric actuator. By continuously monitoring and adjusting the operating frequency, the system ensures optimal amplitude output while minimizing energy loss and heat generation, thus resolving the contradiction between power output and temperature control.
2Manufacturing precision
If the drive frequency is not precisely controlled at resonant frequency, then the system is simpler to operate, but the needle stroke amplitude decreases and temperature efficiency worsens
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the phase difference between voltage and current signals to detect resonant frequency conditions. This feedback mechanism automatically adjusts the drive frequency to maintain optimal resonance, ensuring precise needle stroke amplitude control while making the system self-regulating and relatively easy to operate despite the sophisticated control logic.
Solution Approach 2:
The system automatically tracks and maintains resonant frequency through self-adjusting feedback control, eliminating the need for manual frequency tuning by the surgeon. The controller autonomously optimizes the operating parameters, making the complex frequency control transparent to the user while ensuring precise amplitude control.
3Temperature
If conventional irrigation/aspiration processes are used, then the device complexity is lower, but the temperature control and protein coagulation prevention becomes inadequate
Solution Approach 1:
The patent introduces an enhanced irrigation system that acts as an intermediary cooling mechanism. The irrigation fluid serves as a heat sink and cooling medium, absorbing excess heat from the ultrasonic tip and preventing temperature rise that could cause protein coagulation. This intermediary cooling approach effectively manages thermal load without requiring fundamental changes to the ultrasonic generation system.
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
The solution dynamically adjusts the drive signal frequency to maintain optimal needle stroke amplitude and reduce temperature rise, enhancing the safety and effectiveness of the phacoemulsification process by preventing protein coagulation and ensuring precise control over the surgical tool.
Implementation Method 1
a piezoelectric actuator configured to vibrate the horn and the needle and having a resonant frequency
Implementation Method 2
adjusts the frequency of the drive signal so as to minimize the measured phase difference, whereby the piezoelectric actuator vibrates at the resonant frequency
Implementation Method 3
phase detection circuitry configured to measure a phase difference between a voltage across the piezoelectric actuator, and a current flowing through the piezoelectric actuator in response to the drive signal
Implementation Method 4
a controller configured to adjust a frequency of the drive signal so as to minimize the measured phase difference, whereby the piezoelectric actuator vibrates at the resonant frequency
Data Source
AI summary
In one embodiments, a phacoemulsification apparatus includes a phacoemulsification probe including a horn, a needle mounted in the horn and configured for insertion into a lens capsule of a human eye, and a piezoelectric actuator configured to vibrate the horn and the needle and having a resonant frequency, a signal generator configured to generate a drive signal to drive a vibration of the piezoelectric actuator, phase detection circuitry configured to measure a phase difference between: a voltage across the piezoelectric actuator, and a current flowing through the piezoelectric actuator in response to the drive signal, and a controller configured to adjust a frequency of the drive signal so as to minimize the measured phase difference, whereby the piezoelectric actuator vibrates at the resonant frequency.