Table 2.
The performance of different acoustic detectors along with their advantages and disadvantages in PAI applications.
| Detectors | Resolution (μm) | Penetration Depth (mm) | Sensitivity | Advantages | Disadvantages |
|---|---|---|---|---|---|
| Fabry–Perot interferometer (FPI) [67,68,69,70,111,112] |
<10 | 0.7–20 | NEP: 80–300 Pa |
- High-resolution image with small active area | - Challenging to fabricate into an array - Mechanical scanning - Smaller penetration depth |
| Micro-ring resonator (MRR) [81,82,113] |
<10 | 0.002–2.2 | NEP: 35–105 Pa |
- Wide angular response - Low NEP over a wide frequency range |
- Challenging to fabricate into an array - Mechanical scanning - Smaller penetration depth |
| Piezoelectric transducer (PZT) [98,114,115] |
200 | >30 | SNR: 18–22 dB |
- Most matured and readily available - Deeper penetration depth |
- Opaque - Not CMOS compatible - Difficulty in fabricating high-density array |
| Capacitive micromachined ultrasound transducer (CMUT) [116,117,118,119,120,121,122,123,124,125,126,127,128,129,130] |
>80 | >50 | SNR: 22–87 dB |
- CMOS compatible - High-density arrays can be fabricated - Deeper penetration depth |
- DC voltage is needed - Dielectric charging |