Multiple Ring Electrode-Based PMUT with Tunable Deflections
Ultrasonic applications such as non-destructive testing, biomedical imaging or range measurements are currently based on piezoelectric bulk transducers. Yet, these kinds of transducers with their mm to cm dimensions are rather impractical in fields in which both frequencies in the kHz region and sma...
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MDPI AG
2025-05-01
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| Series: | Micromachines |
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| Online Access: | https://www.mdpi.com/2072-666X/16/6/623 |
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| author | Jan Helmerich Manfred Wich Annika Hofmann Thomas Schaechtle Stefan Johann Rupitsch |
| author_facet | Jan Helmerich Manfred Wich Annika Hofmann Thomas Schaechtle Stefan Johann Rupitsch |
| author_sort | Jan Helmerich |
| collection | DOAJ |
| description | Ultrasonic applications such as non-destructive testing, biomedical imaging or range measurements are currently based on piezoelectric bulk transducers. Yet, these kinds of transducers with their mm to cm dimensions are rather impractical in fields in which both frequencies in the kHz region and small-feature sizes are required. This fact mainly relates to the inverse relationship between the resonance frequency constant and the transducers’ dimension, yielding a higher frequency and attenuation with a decreasing size. Piezoelectric micromachined ultrasonic transducers (PMUTs), in comparison, incorporate a small-scale µm design while preserving the operating frequency in the desired kHz range. This contribution presents the detailed manufacturing of such a PMUT with a multiple ring electrode‑based structure to additionally adjust the sound pressure fields. The PMUT will be characterized by its deflection in air along with the characterization of the piezoelectric material lead zirconate titanate (PZT) itself. The measurements showed a maximum polarization of 21.8 µC/cm<sup>2</sup> at 50 kV/cm, the PMUT’s displacement of 30.50 nm/V in air when all electrodes are driven, and an adjustable deflection via different electrode excitations without the need for additional hardware. The ring design also offered the possibility to emit two distinct frequencies simultaneously. These results demonstrate the potential of the designs for small-feature-size applications as they are in high demand for implantable devices, miniaturized ultrasonic-based communication or drug delivery. |
| format | Article |
| id | doaj-art-e1fa306899624a448eeeca57cd6de359 |
| institution | Kabale University |
| issn | 2072-666X |
| language | English |
| publishDate | 2025-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Micromachines |
| spelling | doaj-art-e1fa306899624a448eeeca57cd6de3592025-08-20T03:27:40ZengMDPI AGMicromachines2072-666X2025-05-0116662310.3390/mi16060623Multiple Ring Electrode-Based PMUT with Tunable DeflectionsJan Helmerich0Manfred Wich1Annika Hofmann2Thomas Schaechtle3Stefan Johann Rupitsch4Laboratory for Electrical Instrumentation and Embedded Systems, Department of Microsystems Engineering (IMTEK), University of Freiburg, 79110 Freiburg, GermanyLaboratory for Electrical Instrumentation and Embedded Systems, Department of Microsystems Engineering (IMTEK), University of Freiburg, 79110 Freiburg, GermanyLaboratory for Electrical Instrumentation and Embedded Systems, Department of Microsystems Engineering (IMTEK), University of Freiburg, 79110 Freiburg, GermanyLaboratory for Electrical Instrumentation and Embedded Systems, Department of Microsystems Engineering (IMTEK), University of Freiburg, 79110 Freiburg, GermanyLaboratory for Electrical Instrumentation and Embedded Systems, Department of Microsystems Engineering (IMTEK), University of Freiburg, 79110 Freiburg, GermanyUltrasonic applications such as non-destructive testing, biomedical imaging or range measurements are currently based on piezoelectric bulk transducers. Yet, these kinds of transducers with their mm to cm dimensions are rather impractical in fields in which both frequencies in the kHz region and small-feature sizes are required. This fact mainly relates to the inverse relationship between the resonance frequency constant and the transducers’ dimension, yielding a higher frequency and attenuation with a decreasing size. Piezoelectric micromachined ultrasonic transducers (PMUTs), in comparison, incorporate a small-scale µm design while preserving the operating frequency in the desired kHz range. This contribution presents the detailed manufacturing of such a PMUT with a multiple ring electrode‑based structure to additionally adjust the sound pressure fields. The PMUT will be characterized by its deflection in air along with the characterization of the piezoelectric material lead zirconate titanate (PZT) itself. The measurements showed a maximum polarization of 21.8 µC/cm<sup>2</sup> at 50 kV/cm, the PMUT’s displacement of 30.50 nm/V in air when all electrodes are driven, and an adjustable deflection via different electrode excitations without the need for additional hardware. The ring design also offered the possibility to emit two distinct frequencies simultaneously. These results demonstrate the potential of the designs for small-feature-size applications as they are in high demand for implantable devices, miniaturized ultrasonic-based communication or drug delivery.https://www.mdpi.com/2072-666X/16/6/623adjustable deflectioncharacterization of piezoelectric materialsmultiple electrode designPMUTPZT annealingultrasonic transducers |
| spellingShingle | Jan Helmerich Manfred Wich Annika Hofmann Thomas Schaechtle Stefan Johann Rupitsch Multiple Ring Electrode-Based PMUT with Tunable Deflections Micromachines adjustable deflection characterization of piezoelectric materials multiple electrode design PMUT PZT annealing ultrasonic transducers |
| title | Multiple Ring Electrode-Based PMUT with Tunable Deflections |
| title_full | Multiple Ring Electrode-Based PMUT with Tunable Deflections |
| title_fullStr | Multiple Ring Electrode-Based PMUT with Tunable Deflections |
| title_full_unstemmed | Multiple Ring Electrode-Based PMUT with Tunable Deflections |
| title_short | Multiple Ring Electrode-Based PMUT with Tunable Deflections |
| title_sort | multiple ring electrode based pmut with tunable deflections |
| topic | adjustable deflection characterization of piezoelectric materials multiple electrode design PMUT PZT annealing ultrasonic transducers |
| url | https://www.mdpi.com/2072-666X/16/6/623 |
| work_keys_str_mv | AT janhelmerich multipleringelectrodebasedpmutwithtunabledeflections AT manfredwich multipleringelectrodebasedpmutwithtunabledeflections AT annikahofmann multipleringelectrodebasedpmutwithtunabledeflections AT thomasschaechtle multipleringelectrodebasedpmutwithtunabledeflections AT stefanjohannrupitsch multipleringelectrodebasedpmutwithtunabledeflections |