Table 1.
MEMS scanning mechanisms developed for in vivo optical endomicroscopy.
| Imaging Modality | Scan | Res (µm) | FOV | Frame Rate (Hz) | Applications | Advantages | Disadvantages |
|---|---|---|---|---|---|---|---|
| Fluorescent Wide-Field | Piezo | 100–300 | ~70–90° | ~30 | GI, respiratory, ear, urinary, reproductive tracts, | High imaging speed, inexpensive laser source, minimal moving parts, commercial devices exist | Relatively low resolution and contrast, no depth sectioning |
| Single-axis Confocal | Piezo, PZT, Electrostatic, Electrothermal, Magnetic | 0.5–5 | 0–150° | >2 | GI, respiratory, ear, urinary, reproductive tracts | High sensitivity provide functional information miniaturization through proximal or distal ends commercial devices exist | Limited contrast and wavelength, limited tissue penetration (<100 µm), limited working distance, increased aberration due to high NA optics |
| Dual-axis Confocal | Electrostatic | 3–6 | 250–1000 µm | >15 | Skin, GI tract, liver, head and neck, pancreas, | Effective out-of-focus rejection of scattered light for high contrast, deep tissue penetration (~400 µm), relatively isotropic resolution | Low NA optics limits sensitivity, challenging alignment of a dual-beam configuration |
| OCT | Piezo, PZT, Electrostatic, Electrothermal, Magnetic | 1–15 | 2000–5000 µm | >60 | GI, respiratory, ear, urinary, reproductive tracts | Impressive miniaturization, high sensitivity, dynamic range, high imaging speed, deep tissue penetration (a few mm) | Label-free imaging, expensive detector array, Short dynamic range along depth |
| Two-photon | Piezo, PZT, Electrostatic, Electrothermal, Magnetic | 0.5–2 | 200–500 µm | >5 | GI, respiratory, tracts | High resolution and contrast, deep tissue penetration (~500 µm ~1 mm) less photobleaching and phototoxicity, Commercial devices exist | Relatively expensive laser source and optics, need dispersion compensation or special fibers to maintain pulse shape |
| Optical resolution photoacoustic microscope (OR-PAM) | Electrostatic and Electrothermal | ~5 | 1000 µm | 10 | Breast, brain | High spatial resolution and contrast high imaging speed, deep tissue penetration (a few mm) | Relatively expensive laser source progress on miniaturization is still ongoing |