Lithotripsy Projectile Frequency Control with Piezoelectric Feedback
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Solution Overview
Problem
Existing lithotripsy devices with combined ultrasound and pneumatic systems face malfunctions due to the impact of the pneumatic projectile on the sonotrode, disrupting the ultrasonic generator's resonance and requiring system restarts, while maximizing fragmentation force and frequency of projectile acceleration remains a challenge.
Innovation Solution
A method and device that determine an optimal frequency for the oscillating movement of a projectile by using the piezo element as a sensor to regulate the projectile's movement, optimizing energy transfer to the calculus, and incorporating a closed-loop control system to minimize interference from ultrasonic vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the pneumatic projectile is accelerated to deliver high energy impacts at high frequency, then the fragmentation force is improved, but the projectile may strike the sonotrode and induce voltage in the ultrasonic generator, causing system malfunction
Solution Approach 1:
The patent employs a feedback mechanism where the current signal from the piezo element is continuously monitored. When the signal exceeds a threshold indicating projectile-sonotrode contact, the system automatically adjusts or stops pneumatic actuation to prevent malfunctions, while allowing high-frequency operation during normal conditions
Solution Approach 2:
The system dynamically adjusts the operating frequency of the pneumatic projectile based on real-time feedback from the ultrasonic generator. The frequency is optimized to maximize fragmentation force while automatically adapting to prevent contact-induced malfunctions, transforming the static frequency operation into a dynamic adaptive process
2Productivity
If the ultrasonic transducer operates at high frequency to maximize stone fragmentation, then the productivity is improved, but the piezo element is more susceptible to voltage induction from projectile impact
Solution Approach 1:
The system uses feedback from the current signal of the piezo element to detect when voltage induction occurs during ultrasonic operation. This enables real-time monitoring and adjustment to maintain high productivity while preventing harmful voltage induction effects
Solution Approach 2:
The patent replaces mechanical contact-based control with an electrical field-based detection system. By monitoring the electrical current signal from the piezo element, the system can detect projectile-sonotrode contact without mechanical sensors, enabling non-intrusive monitoring that maintains ultrasonic frequency operation
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
Ensures trouble-free operation of the lithotripsy device by maximizing fragmentation force and frequency, reducing system malfunctions, and enhancing stone fragmentation efficiency.
Implementation Method 1
A current signal of the piezo element, which results from a vibration at the first stop or second stop by the projectile, is detected
Implementation Method 2
repeatedly accelerating a projectile by means of compressed air from a first proximal stop to a second distal stop and from the second stop to the first stop
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for determining an optimal frequency of an oscillating movement of a force-accelerated projectile of an intracorporeal pneumatic lithotripsy apparatus, including the following steps: repeatedly accelerating the projectile from a first proximal stop of an acceleration path to a second distal stop, and from the second stop to the first stop, wherein a piezo element is arranged between a proximally arranged counter bearing and a distally arranged horn and is mechanically coupled to the counter bearing and to the horn, and the horn has a distally arranged sonotrode, wherein the acceleration path is arranged in the interior of the counter bearing and of the horn and the first stop is arranged at a distal end of the counter bearing and the second stop is arranged at a distal end of the horn, detecting an electrical signal from the piezo element caused by a tremor at the first stop and/or the second stop as a result of the projectile; and using the detected electrical signal to control a medium which generates the force and which is used to accelerate the projectile from the first stop of the acceleration path to the second stop, and from the second stop to the first stop.