@inproceedings{64798,
abstract = {{Lead-containing piezoelectric ceramics are still the base for today’s ultrasonic transducers used in broad applications. This is partly due to missing powerful lead-free piezoelectric ceramic parts in the commercial market. There has been much research on lead-free materials but developing them into marketable parts seems to be an ongoing process. The actual exemption of ROHS has expired, but as the new exemption has already been requested, ceramic suppliers keep on selling lead containing products. Nevertheless, these should be replaced by lead-free alternatives for environmental and health issues.
This contribution focuses on exploring the technological readiness level of lead-free hard piezoceramics for prestressed ultrasonic transducers. A small series of bolted Langevin transducers was set up with standard PZT material and three commercial lead-free variants. Results of the building process from individual ring ceramic characteristics to transducer load tests are presented. The main finding of this study is that the lead-free materials technically can compete with the standard PZT for medium-power applications. Some adaptations in the ultrasonic system must be done: the geometry must be altered to fit resonance frequency, and higher voltages or thinner ceramics are needed to achieve the same vibration level at low load. For reaching same power, the volume of lead-free ceramics must be 1.5 to 3 times larger. As already promoted in literature, mechanical losses at high vibration levels are smaller for the lead-free materials. This might help to argument lead-free piezoelectric materials in some applications.
References
1. Directive 2011/65/EU of the European Parliament and of the Council of 8 June 2011 on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment. EUR-Lex Document 02011L0065-20240801. Available online: http://data.europa.eu/eli/dir/2011/65/2024-08-01 (accessed on 24 January 2025).
2. Langevin, P. (1918) Method and Apparatus for Transmitting and Receiving Submarine Elastic Waves Using the Piezoelectric Properties of Quartz. French Patent Office; Patent No. FR505703.
3. Hemsel, T.; Twiefel, J. (2023) Piezoelectric Ultrasonic Power Transducers. In Encyclopedia of Materials: Electronics; Academic Press: Oxford, UK; pp. 276–285. https://doi.org/10.1016/b978-0-12-819728-8.00047-4.
4. ATHENA Technologie Beratung GmbH (2025) Description of Ultrasound Generator. Available online: http://shop.myathena.de/epages/12074748.sf/de_DE/?ObjectPath=/Shops/12074748/Products/AM200 (accessed on 13 January 2025).
5. Littmann, W.; Hemsel, T.; Kauczor, C.; Wallaschek, J.; Sinha, W. (2003) Load-adaptive phase-controller for resonant driven piezoelectric devices. Proc. World Congr. Ultrason. 2003, 48, 547–550.
6. Scheidemann, C., Bornmann, P., Littmann, W., & Hemsel, T. (2025). Lead-Free Ceramics in Prestressed Ultrasonic Transducers. Actuators, 14(2), 55. https://doi.org/10.3390/act14020055
}},
author = {{Scheidemann, Claus and Bornmann, Peter and Littmann, Walter and Hemsel, Tobias}},
keywords = {{lead free piezoelectric ceramics, bolted Langevin transducer, medium power ultrasound.}},
location = {{Vilnius, Lithuania}},
title = {{{Bolted Langevin transducers with leadfree piezoelectric ceramics}}},
year = {{2025}},
}
@inproceedings{62302,
abstract = {{The degree of crosslinking in unidirectional prepreg materials was investigated using differential scanning calorimetry to assess their curing behavior and thermal characteristics. To complement these measurements with a non-destructive, in-situ method, the propagation properties of guided acoustic waves in cured carbon fibre-reinforced epoxy plates were analysed. Correlations between the degree of crosslinking and acoustically determined mechanical properties were drawn to enable a future non-destructive evaluation approach.}},
author = {{Irmak, Hayrettin and Claes, Leander and Wu, Shuang and Marten, Thorsten and Tröster, Thomas}},
booktitle = {{2025 International Congress on Ultrasonics}},
isbn = {{978-3-910600-08-9}},
keywords = {{fibre-reinforced polymers, differential scanning calorimetry, degree of crosslinking, guided waves, ultrasound}},
location = {{Paderborn, Germany}},
pages = {{235–238}},
publisher = {{AMA Service GmbH}},
title = {{{Assessment of the influence of curing parameters on fibre reinforced epoxy composite properties using guided ultrasonic waves}}},
doi = {{10.5162/ultrasonic2025/c13-b3}},
year = {{2025}},
}
@inbook{33500,
abstract = {{This article is dedicated to piezoelectric ultrasonic power transducers that differ to well known medical ultrasonic diagnostic apparatus or non destructive testing devices by the level of power in use; typically several tens of up to more than thousand watts are used in a multitude of different applications. After a short introduction including historical development, the first focus is on theoretical background of the operating principle, design and mechanical modeling. As piezoelectric elements transform electrical to mechanical energy and vice versa, equivalent circuit modeling is also described. After that, sample applications are delineated by the matter wherein ultrasound generates unique effects: incredible high pressure level as well in air as in water, micro-bubbles generating temperature peaks for very short time instances in fluids, acoustoplastic effect, enhancement of diffusion and recrystallization in solids, friction manipulation, incremental deformation and micro-cracking of surfaces, or even generation of macroscopic movements in motors. At the end, some future directions ranging from novel modeling approaches to advanced control and new materials are addressed.}},
author = {{Hemsel, Tobias and Twiefel, Jens}},
booktitle = {{Reference Module in Materials Science and Materials Engineering}},
isbn = {{978-0-12-803581-8}},
keywords = {{Equivalent circuit model, Langevin transducer, Lumped parameter model, Piezoelectric transducer, Ultrasonic processes, Ultrasound}},
publisher = {{Elsevier}},
title = {{{Piezoelectric Ultrasonic Power Transducers}}},
doi = {{10.1016/b978-0-12-819728-8.00047-4}},
year = {{2022}},
}
@article{41906,
abstract = {{Abstract
Background
Due to the steadily increasing life expectancy of the population, the need for medical aids to maintain the previous quality of life is growing. The basis for independent mobility is a functional locomotor system. The hip joint can be so badly damaged by everyday wear or accelerated by illness that reconstruction by means of endoprostheses is necessary.
Results
In order to ensure a high quality of life for the patient after this procedure as well as a long service life of the prosthesis, a high-quality design is required, so that many different aspects have to be taken into account when developing prostheses. Long-term medical studies show that the service life and operational safety of a hip prosthesis by best possible adaptation of the stiffness to that of the bone can be increased. The use of additive manufacturing processes enables to specifically change the stiffness of implant structures.
Conclusions
Reduced implant stiffness leads to an increase in stress in the surrounding bone and thus to a reduction in bone resorption. Numerical methods are used to demonstrate this fact in the hip implant developed. The safety of use is nevertheless ensured by evaluating and taking into account the stresses that occur for critical load cases. These results are a promising basis to enable longer service life of prostheses in the future.
}},
author = {{Risse, Lena and Woodcock, Steven Clifford and Brüggemann, Jan-Peter and Kullmer, Gunter and Richard, Hans Albert}},
issn = {{1475-925X}},
journal = {{BioMedical Engineering OnLine}},
keywords = {{Radiology, Nuclear Medicine and imaging, Biomedical Engineering, General Medicine, Biomaterials, Radiological and Ultrasound Technology}},
number = {{1}},
publisher = {{Springer Science and Business Media LLC}},
title = {{{Stiffness optimization and reliable design of a hip implant by using the potential of additive manufacturing processes}}},
doi = {{10.1186/s12938-022-00990-z}},
volume = {{21}},
year = {{2022}},
}
@inproceedings{14852,
abstract = {{In a variety of industrial applications, liquids are atomized to produce aerosols for further processing. Example applications are the coating of surfaces with paints, the application of ultra-thin adhesive layers and the atomization of fuels for the production of combustible dispersions. In this publication different atomizing principles (standing-wave, capillary-wave, vibrating-mesh) are examined and discussed. Using an optimized standing-wave system, tough liquids with viscosities of up to about 100 Pas could be successfully atomized.}},
author = {{Dunst, Paul and Bornmann, Peter and Hemsel, Tobias and Littmann, Walter and Sextro, Walter}},
booktitle = {{Conference Proceedings - The 4th Conference on MicroFluidic Handling Systems (MFHS2019)}},
editor = {{Lötters, Joost and Urban, Gerald}},
keywords = {{atomization, ultrasound, standing-wave, capillarywave, vibrating-mesh}},
location = {{Enschede, The Netherlands}},
pages = {{140--143}},
title = {{{Atomization of Fluids with Ultrasound}}},
year = {{2019}},
}
@inproceedings{9783,
abstract = {{To optimize the ultrasound irradiation for cavitation based ultrasound applications like sonochemistry or ultrasound cleaning, the correlation between cavitation intensity and the resulting effect on the process is of interest. Furthermore, changing conditions like temperature and pressure result in varying acoustic properties of the liquid. That might necessitate an adaption of the ultrasound irradiation. To detect such changes during operation, process monitoring is desired. Labor intensive processes, that might be carried out for several hours, also require process monitoring to increase their reliability by detection of changes or malfunctions during operation. In some applications cavitation detection and monitoring can be achieved by the application of sensors in the sound field. Though the application of sensors is possible, this necessitates modifications on the system and the sensor might disturb the sound field. In other applications harsh, process conditions prohibit the application of sensors in the sound field. Therefore alternative techniques for cavitation detection and monitoring are desired. The applicability of an external microphone and a self-sensing ultrasound transducer for cavitation detection were experimentally investigated. Both methods were found to be suitable and easily applicable.}},
author = {{Bornmann, Peter and Hemsel, Tobias and Sextro, Walter and Maeda, Takafumi and Morita, Takeshi}},
booktitle = {{Ultrasonics Symposium (IUS), 2012 IEEE International}},
issn = {{1948-5719}},
keywords = {{cavitation, chemical reactors, microphones, process monitoring, reliability, ultrasonic applications, ultrasonic waves, acoustic properties, cavitation based ultrasound applications, cavitation intensity, change detection reliability, external microphone, malfunction detection reliability, nonperturbing cavitation detection, nonperturbing cavitation monitoring, process monitoring, self-sensing ultrasound transducer, sonochemical reactors, sonochemistry, ultrasound cleaning, ultrasound irradiation, Acoustics, Liquids, Monitoring, Sensors, Sonar equipment, Transducers, Ultrasonic imaging}},
pages = {{1141--1144}},
title = {{{Non-perturbing cavitation detection / monitoring in sonochemical reactors}}},
doi = {{10.1109/ULTSYM.2012.0284}},
year = {{2012}},
}