Miniaturized Acoustic Concentrators for Local Generation of Ultrasonic Waves
Bibliographic record
Abstract
Ultrafast 3D ultrasound imaging is a rapidly growing research field that enables real-time imaging at a high frame rate and in a non-invasive manner. This technology finds applications in areas such as functional brain imaging, cardiac electrophysiology, and elastography. Currently, to achieve ultrafast 3D ultrasound, plane or diverging waves from virtual sources located behind the ultrasound probe are used. These virtual sources can be considered as focal points during emission, allowing for improved transmission of ultrasonic energy. However, they have limitations in terms of transmitted energy, complex electronics, and timing issues, which impact the quality of the resulting images. To address this, a study was conducted to design and experiment with new miniaturized ultrasound transmitters based on cylindrical waveguides with tapered sections. These transmitters, with a diameter of approximately 100 µm, can replace the virtual sources. A numerical study based on 2D axisymmetric Finite Element Modeling (FEM) was performed to model the transmission and reflection of longitudinal ultrasonic waves through a large-diameter cylindrical rod (D1) to another rod with a smaller variable diameter (D2). The results demonstrated that the transmission depends on the diameter ratio between the rods and the frequency used. Various longitudinal modes (L0, L1, L2, etc.) were identified, and their transmission was studied with respect to frequency and geometrical parameters. A preliminary experimental study was conducted on a cylindrical steel rod with a diameter of 6 mm and a piezoelectric disc. Measurements were performed using a Laser Doppler Vibrometer (LDV) to assess the wave-numbers and amplitudes of the longitudinal modes propagating in various sections of the rod, and to determine the reflected and transmitted energy corresponding to each incident mode. The frequencies analyzed ranged up to 3 MHz. The obtained results were then compared with theoretical predictions for further analysis. Future work includes the design of a concentrator for a specific imaging configuration.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".