Phacoemulsification Circuit with Dual-Frequency Cavitation Control
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Solution Overview
Problem
Existing phacoemulsification procedures face challenges in efficiently fragmenting and emulsifying cataractous lenses due to issues with cavitation, which can lead to partial or total occlusions and heating at the incision site, affecting followability and tissue disintegration.
Innovation Solution
A dual frequency voltage producing circuit is employed, combining a low-frequency and high-frequency LC network to drive a piezoelectric crystal transducer, allowing the phacoemulsification needle to vibrate at ultrasonic and high ultrasonic frequencies, optimizing cavitation and reducing heating by modulating between these frequencies based on surgical conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single ultrasonic frequency is used to fragment the lens, then effective tissue disintegration is achieved, but cavitation occurs leading to occlusions and heating at the incision site
Solution Approach 1:
The patent applies periodic action by alternating between high-frequency ultrasonic vibrations (for effective lens fragmentation) and low-frequency vibrations (to reduce cavitation and heating). This periodic switching between different frequency regimes allows the system to achieve productive tissue disintegration while periodically mitigating harmful thermal effects and occlusions at the incision site.
Solution Approach 2:
The system dynamically adjusts the vibration frequency based on real-time surgical conditions. The circuit can switch between high-frequency mode (above 60 kHz) for optimal emulsification and low-frequency mode (below 60 kHz) to reduce cavitation, allowing adaptive control of the ultrasonic handpiece to maintain effectiveness while minimizing harmful effects during the procedure.
2Object-affected harmful factors
If high ultrasonic frequency is used to reduce heating, then followability improves, but tissue disintegration effectiveness decreases
Solution Approach 1:
The system uses periodic action by alternating between high-frequency ultrasonic vibrations (which reduce heating and improve followability) and low-frequency vibrations (which enhance tissue disintegration effectiveness). This temporal alternation allows the system to periodically achieve both goals - reducing thermal damage while maintaining effective lens fragmentation capability.
Solution Approach 2:
The dual-frequency circuit enables dynamic switching between frequency regimes based on surgical needs. When heating control is prioritized, the system operates at high frequency; when tissue disintegration effectiveness is prioritized, it switches to low frequency, providing dynamic optimization of both competing objectives during the surgical procedure.
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
Enhances followability and reduces heating at the incision site, resulting in more effective tissue disintegration and emulsification with minimal corneal damage.
Implementation Method 1
A phacoemulsification needle extends from a handpiece including a piezoelectric crystal transducer
Implementation Method 2
The two frequencies produce different surgical effects when used to emulsify a cataractous lens
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
Disclosed is a surgical instrument directed to phacoemulsification for cataract eye surgery. The instrument generally includes a dual frequency voltage producing circuit comprising a low-frequency voltage pathway with a low-frequency LC Network and a high-frequency voltage pathway with a high-frequency LC network. A phacoemulsification needle extends from a handpiece able to be driven by a piezoelectric transducer. The piezoelectric transducer is electrically connected to the dual frequency voltage producing circuit. The high-frequency voltage pathway is electrically tuned with the physical high natural frequency of the handpiece and the low-frequency voltage pathway is electrically tuned with the physical low natural frequency of the handpiece for efficient transfer of energy.