Physics / mechanism
Biophotonics is the application of photonic techniques — light generation, detection, and manipulation — to biological systems. Core mechanisms span fluorescence imaging (FLIM, FRET), Raman spectroscopy, optical coherence tomography (OCT), and photoplethysmography (PPG). Key parameters: wavelength selection (NIR “biological window” 650–1350 nm minimises tissue scattering), photon budget, signal-to-noise ratio, and spatial resolution (diffraction-limited ~200 nm for confocal; sub-100 nm for STED/PALM). State of the art: single-molecule detection in vivo, chip-scale OCT with <5 µm axial resolution, and wearable PPG sensors achieving clinical-grade SpO₂ accuracy. Photonic integrated circuits (PICs) are collapsing system cost and size, enabling point-of-care diagnostics.
Competitive landscape
Competing and adjacent approaches include electrical biosensing (electrochemical, impedance — lower cost, lower specificity), MRI/CT (gold standard imaging but bulky, expensive, ionising for CT), and ultrasound (portable, no photons, inferior molecular contrast). Within photonics, free-space optics competes with fibre and integrated approaches on cost/form-factor axes.
| Approach | Resolution | Molecular specificity | Miniaturisation |
|---|---|---|---|
| PIC-based OCT | 1–5 µm | Low | High |
| Raman spectroscopy | Diffraction-limited | High | Medium |
| Electrochemical sensing | N/A | Medium | High |
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.