The Future of Everything Best of: The future of transparent tissue
Oct 31, 2025
Guosong Hong, a materials scientist and bioengineer at Stanford, dives into groundbreaking research that uses a common food dye to make biological tissues transparent. He discusses the challenges of light penetration in tissue and his innovative approach to matching refractive indices without damaging cells. The potential applications are vast, from improving cancer detection in human skin to allowing doctors to see internal organs in live animals. Plus, learn how this breakthrough might redefine noninvasive medical imaging!
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Why Tissue Blocks Light
- Biological tissues scatter light because microscopic components (lipids, proteins) have higher refractive indices than water.
- That microscopic refractive-index mismatch, not color, fundamentally limits optical penetration into tissue.
UV Absorption Controls Visible Refractive Index
- UV absorption at short wavelengths determines refractive index at visible wavelengths via Kramers–Kronig relations.
- Engineering UV absorption in water can raise its visible refractive index to match lipids and reduce scattering.
Dye-Induced Index Matching
- Dissolving a UV-absorbing dye into water raises water's refractive index at red wavelengths without removing lipids.
- This refractive-index matching makes tissue translucent or transparent without destroying tissue components.