Table 3.
Comparison of different EM-wave-based methods.
| Technology | Penetration | Target | Sensitivity | Selectivity | System Size | Cost |
|---|---|---|---|---|---|---|
| NIR | >1 mm | ISF, blood | High | Good | Portable | Low |
| MIR | Several μm | ISF | High | Good, better than NIR spectroscopy | Large | High |
| PA | Better than IR spectroscopy | ISF, blood | High | Good | Portable | Low |
| Fluorescence | <1 mm | Tear, ISF, blood | High | Excellent | Portable | Low |
| Raman | <1 mm | ISF, tears | Low | Excellent | Portable | Medium |
| OCT | <1 mm | ISF | High | Poor | Portable | Medium |
| THz | ~100 μm | ISF | High | Good | Large | High |
| Microwave | >1 mm | Blood, ISF | High | Poor | Portable/wearable | Very Low |
ISF, interstitial fluid; OCT, Optical Coherence Tomography.