This document is concerned with examining whether sound output levels from ultrasonic therapy devices, in particular their ultrasonic transducers, can be determined by means of piezoceramic sensors.
Table of Contents
A Introduction
B Basics of Ultrasound
B.1 Selected definitions of terms
C Basics of the Ultrasonic Therapy
C.1 Effects at and in the human tissue
C.2 The effect spectrum and indications
D Basics of the Piezoceramic Sensor
D.1 Historical excursion
D.2 Principles of functioning
D.3 Production and material
D.4 Forms used and their basic oscillation
E Investigation of Ultrasonic Therapy Devices
E.1. Results of the investigation
F Series of Experiments to Find Characteristics
F.1 “Voltage” test setup”
F.1.1 Series of voltage-measurements
F.1.2 Evaluation and discussion of the series of experiments
F.2 “Temperature” measurement setup
F.2.1 Series of temperature measurements
F.2.1.1 Results of the series of temperature measurements
F.2.2 Thermography of the ultrasonic transducer
F.2.2.1 Results of the thermography
G Final Conclusions
G.1 Future prospects of a handheld measuring instrument
Research Objectives and Themes
This study investigates the feasibility of using piezoceramic sensors as a cost-effective and practical alternative for measuring the ultrasonic power output of medical therapy devices, replacing current inconvenient and expensive gravimetric procedures.
- Fundamental study of ultrasound and piezoelectric sensor technology.
- Empirical investigation of market-available ultrasonic therapy devices.
- Development and testing of a laboratory setup using piezoceramic sensors for voltage measurement.
- Analysis of thermal effects on the measurement process and transducer performance.
- Conceptualization of a handheld, microcontroller-based measuring instrument.
Excerpt from the Book
D.1 Historical excursion
The piezoelectric effect was discovered by the French physicists Pierre and Jacques Curie in 1880. The two brothers experimented with natural crystals (salt, tourmaline, quartz) and discovered that when certain crystals are mechanically deformed, they are electrically charged or polarised.
They also found that by applying an electric current to a crystal, it deformed. This reciprocal effect was described as the inverse piezoelectric effect.
The discoveries of the French physicists formed the basis for the sonar, developed in around 1940 for navy vessels to locate submarines.
The breakthrough in piezotechnology was made by Russian and American scientists in the years leading up to the 1950s as they succeeded synthesising the first PZT (plumbum-zirconate-titanate) compounds. These compounds remain the dominating materials for piezotechnology thanks to their excellent properties [11].
Summary of Chapters
A Introduction: Outlines the necessity of regular, cost-effective safety inspections for medical ultrasonic therapy devices and introduces the feasibility of using piezoceramic sensors for power measurement.
B Basics of Ultrasound: Defines fundamental physical principles of ultrasonic waves and explains the essential terminology and wave behavior required for understanding the therapy.
C Basics of the Ultrasonic Therapy: Describes the technical composition of therapy devices and the physiological impacts, specifically mechanical and thermal effects, of ultrasound on human tissue.
D Basics of the Piezoceramic Sensor: Provides a historical overview and explains the technical functioning of piezoceramic materials, including their production processes and geometric forms.
E Investigation of Ultrasonic Therapy Devices: Summarizes the technical data of common devices on the German market, establishing the parameters necessary for the experimental setup.
F Series of Experiments to Find Characteristics: Details the laboratory test configurations, including voltage and temperature measurement setups, and discusses the evaluation of results.
G Final Conclusions: Synthesizes the results of the feasibility study, highlighting decisive parameters for measurement accuracy and proposing future developments for a handheld device.
Keywords
Ultrasound, Piezoceramic sensor, Medical device technology, Ultrasonic therapy, Power measurement, Transducer, Feasibility study, Piezoelectric effect, Calibration, Microcontroller, Signal processing, Temperature stability, Impedance, Medical Devices Directive, Material science.
Frequently Asked Questions
What is the primary objective of this work?
The primary objective is to prove that sound output levels of ultrasonic therapy devices can be accurately determined using piezoceramic sensors, aiming to develop a practical and affordable handheld measuring instrument.
What are the core technical fields covered?
The study covers ultrasonic physics, piezoelectric material science, electronic circuit design for signal filtering, and medical device safety regulations.
Which scientific methods were employed?
The research combines theoretical literature review with empirical laboratory experiments, including voltage measurements, temperature monitoring, and thermographic analysis to evaluate sensor stability.
How is the output of the ultrasonic transducer measured?
The system uses a piezoceramic oscillator as a detector, which converts mechanical pressure fluctuations into electrical voltage; this signal is then filtered by a bandpass circuit and processed.
What is the role of the coupling medium?
Degassed water is used as the coupling medium to ensure efficient sound transfer between the transducer and the sensor, while also managing the heat dissipation required for stable measurement.
What were the main findings regarding temperature?
The experiments demonstrated that operating temperatures remain within a safe range for the piezoceramic materials, and while heating occurs in the electronics, it does not impede the measurement accuracy of the probe surface.
Why are standard piezoceramic materials chosen over custom-made ones?
Standard materials are more cost-effective for feasibility and testing, though the study suggests that custom-made crystals may be necessary for higher precision in a finalized series production.
How is the measurement data converted into output power?
The measured DC voltage is converted into output values via a microcontroller, which uses pre-programmed trend curves based on type-specific output characteristics of the therapy devices.
What impact does the distance between transducer and sensor have?
Parallelism and a specific distance (optimal range 5 mm to 7 mm) are critical to ensuring the sound makes perpendicular contact with the sensor, which is essential for reproducible power measurements.
Are the measured results affected by production tolerances?
Yes, production tolerances of the piezoceramic components (up to ± 20%) impact result consistency; however, the study proves that measurement is still achievable even with standard components.
- Arbeit zitieren
- Thomas Lekscha (Autor:in), 2010, Technical procedure of an Ultrasound measuring instrument for the power measurement at medical therapy devices, München, GRIN Verlag, https://www.hausarbeiten.de/document/150123
