6 MHz 3D-Printed Barium Titanate Annular Array Transducer
This 4-element annular array transducer is fabricated entirely by Mask-Image-Projection-based Stereolithography (MIP-SL), an additive manufacturing process that enables printing of complex piezoelectric geometries unattainable with conventional dicing or etching methods. The array is printed from barium titanate (BaTiO₃) nanoparticles suspended in photocurable resin, then debinded and sintered to achieve dense ceramic structures with stable piezoelectric properties. The annular geometry—four concentric elements with 400 µm thickness—operates at a center frequency of ~6 MHz with electromechanical coupling coefficient kₜ = 0.465. Compared to a single-element transducer of identical aperture and frequency, the annular array provides significantly improved lateral resolution across an extended depth of field (5.6–8.0 mm). This work demonstrates that 3D printing enables functional piezoelectric arrays with arbitrary element shapes, offering a pathway toward customized transducer geometries for medical imaging, particle manipulation, and therapeutic ultrasound.
Parameter | Value |
|---|---|
Array Type | Annular array (concentric rings) |
Number of Elements | 4 (working) |
Center Frequency | 5.72–6.39 MHz (element dependent) |
Bandwidth (‑6 dB) | 12.9–23.6% |
Piezoelectric Material | BaTiO₃ (sintered nanoparticle ceramic) |
Fabrication Method | Mask‑Image‑Projection Stereolithography (MIP‑SL) |
Element Thickness | 400 μm |
Element Area | ~13.5 mm² per element |
Electromechanical Coupling (kₜ) | 46.3–46.5% |
Piezoelectric Constant (d₃₃) | 146–160 pC/N |
Dielectric Constant | ~340 |
Dielectric Loss | 0.018–0.020 |
Density (sintered) | 5.62–5.64 g/cm³ |
Matching Layer | Parylene (10 μm) |
Backing Material | Epo‑Tek 301 (epoxy, ~6 MRayl) |
Measured Lateral Resolution (5.6–8.0 mm depth) | 1.05–1.1 mm (array) vs. 1.1–1.4 mm (single element) |
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