Tapered Phacoemulsification Needle Ultrasonic Node Placement
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Solution Overview
Problem
Current phacoemulsification procedures face challenges in efficiently emulsifying cataractous lenses due to inadequate control over cavitation and heat generation during ultrasonic needle vibrations, leading to reduced followability and potential tissue damage.
Innovation Solution
A phacoemulsification device that switches between ultrasonic frequencies above and below 60 kHz, utilizing a hollow titanium needle with a piezoelectric transducer to produce either a low or high ultrasonic standing wave, with a node of minimum amplitude at the high frequency mode, reducing cavitation and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic needle vibrations are used to emulsify cataractous lenses, then emulsification efficiency is improved, but cavitation and heat generation increase causing tissue damage
Solution Approach 1:
The device dynamically switches between two ultrasonic frequencies (above and below 60 kHz) to optimize emulsification while minimizing tissue damage. The frequency switching creates alternating patterns of cavitation and heating that enhance emulsification efficiency while allowing tissue cooling intervals, thereby reducing cumulative thermal damage and excessive cavitation effects.
Solution Approach 2:
The patent implements periodic action by alternating between high frequency (above 60 kHz) and low frequency (below 60 kHz) ultrasonic modes. This periodic frequency switching creates a rhythm of intense emulsification followed by cooling periods, which maintains emulsification effectiveness while preventing excessive heat accumulation and tissue damage.
2Productivity
If high ultrasonic frequency above 60 kHz is used, then emulsification efficiency is improved, but heat generation increases
Solution Approach 1:
The system dynamically adjusts operating frequency between above and below 60 kHz to balance emulsification efficiency and heat generation. During high-frequency phases, emulsification is maximized; during low-frequency phases, heat generation is reduced, creating a dynamic equilibrium that maintains effectiveness while controlling temperature.
Solution Approach 2:
Periodic switching between high and low frequency modes creates alternating cycles of heating and cooling. The high-frequency phases generate necessary heat for emulsification, while low-frequency phases allow heat dissipation, preventing excessive temperature accumulation that would damage surrounding tissue.
3Temperature
If low ultrasonic frequency below 60 kHz is used, then heat generation is reduced, but emulsification efficiency decreases
Solution Approach 1:
The device uses dynamic frequency switching to compensate for reduced emulsification efficiency at low frequencies. By alternating between low-frequency (cooling) and high-frequency (emulsification) modes, the system maintains overall emulsification productivity while benefiting from the reduced heat generation during low-frequency phases.
Solution Approach 2:
Periodic low-frequency ultrasonic action provides cooling intervals that reduce heat generation, while the alternating high-frequency phases maintain emulsification efficiency. This periodic alternation ensures that even though low frequency alone would reduce productivity, the combined cyclic approach maintains overall efficiency while controlling temperature.
4Productivity
If continuous ultrasonic vibration is used, then emulsification efficiency is improved, but followability decreases due to excessive cavitation
Solution Approach 1:
The patent employs periodic switching between frequency modes to create alternating phases of cavitation activity. During high-frequency phases, emulsification is maximized with controlled cavitation; during low-frequency phases, cavitation activity is reduced, allowing the system to maintain followability while preserving emulsification efficiency over the complete cycle.
Solution Approach 2:
Dynamic frequency adjustment creates variable cavitation patterns that prevent continuous excessive cavitation. The system adapts between high and low frequency modes to optimize the balance between emulsification productivity and followability, ensuring that cavitation remains effective for emulsification without becoming excessive and compromising surgical control.
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 tissue damage by controlling cavitation patterns and heat generation, allowing for more efficient emulsification and aspiration of cataractous lens material.
Implementation Method 1
a handpiece that includes a piezoelectric transducer; the piezoelectric transducer configured to periodically vibrate the hollow titanium needle
Implementation Method 2
ultrasonic actuation at a specific frequency is used to break the lens within the lens capsule of the eye
Implementation Method 3
the piezoelectric transducer configured to periodically vibrate the hollow titanium needle at either a low mode or a high mode
Implementation Method 4
the substantially cylindrical portion possessing a single node of minimum amplitude at the high mode
Implementation Method 5
a tapered section between the transducer and the substantially cylindrical portion of the needle
Data Source
AI summary
Disclosed is a surgical instrument directed to phacoemulsification for cataract eye surgery. The instrument generally includes a hollow titanium needle extending from a vibration generating handpiece. Together, the hollow needle and handpiece form an aspiration pathway to suck cataractous debris from an eye. A piezoelectric transducer in the handpiece generates both high and low ultrasonic frequency vibrations that rings the needle. The low frequency produces a node-free standing wave along the needle and the high frequency produces a standing wave along the needle with a node of minimum amplitude along the needle. Both frequencies produce a high anti-node at the needle's tip. The low frequency causes higher cavitation for emulsifying the cataract and the high frequency facilitates fragmentation of the cataract with a low heat portion of the needle at the eye incision point. The placement of the node along the needle can be tailored by way of a tapered section in a step horn region of the handpiece.