Three‐dimensional irradiance and temperature distributions resulting from transdermal application of laser light to human knee—A numerical approach

Abstract

The use of light for therapeutic applications requires light‐absorption by cellular chromophores at the target tissues and the subsequent photobiomodulation (PBM) of cellular biochemical processes. For transdermal deep tissue light therapy (tDTLT) to be clinically effective, a sufficiently large number of photons must reach and be absorbed at the targeted deep tissue sites. Thus, delivering safe and effective tDTLT requires understanding the physics of light propagation in tissue. This study simulates laser light propagation in an anatomically accurate human knee model to assess the light transmittance and light absorption‐driven thermal changes for eight commonly used laser therapy wavelengths (600–1200 nm) at multiple skin‐applied irradiances (W cm−2) with continuous wave (CW) exposures. It shows that of the simulated parameters, 2.38 W cm−2 (30 W, 20 mm beam radius) of 1064 nm light generated the least tissue heating −4°C at skin surface, after 30 s of CW irradiation, and the highest overall transmission—approximately 3%, to the innermost muscle tissue.

Flexible Wearable Plasmonic Paper-Based Microfluidics with Expandable Channel and Adjustable Flow Rate for Portable Surface-Enhanced Raman Scattering Sweat Sensing

“…We simulated higher-body-temperature locations or a population temperature rise on the thermostat heating plate (Figure S6a). The results show that the maximum temperature increase for in situ detection at initial temperatures of 30 and 37 °C is 36.3 and 44.5 °C, respectively (Figure S6b), within the tolerable temperature range of skin tissue. − In addition to thermal damage, the laser used in SERS detection may also cause damage to superficial skin tissue. We verified the laser-blocking effect of the device by using a double-sided carbon tape as the laser-blocking layer (Figure S7).…”