Biophotonics in China

Abstract

Biophotonics is a highly interdisciplinary field where physicists, chemists, biologists, physicians and engineers work together to solve the problems appearing in biology and medicine. In China, the Biophotonics discipline is often referred to as Biomedical Photonics, under the first‐level disciplines Biomedical Engineering or Optical Engineering, and was initiated in the late 1990s. Over the past 20 years, biophotonics research in China expanded extraordinarily and has reached the frontiers of the world‐level sciences. This white paper introduces the research groups in the biophotonics field in China, and their representative contributions.

Optical windows for head tissues in near‐infrared and short‐wave infrared regions: Approaching transcranial light applications

“…The theory has been developed with an assumption that multiple light scattering in turbid medium splits the traversed light into coherent (ballistic) and diffusive components [46][47][48]. The solution to the diffusion equation, which considers both ballistic and diffusive modes, can be presented [18] as…”

“…with optical properties of biological tissues, which results in a limited light penetration. The penetration of light in visible and the shortest near-infrared (NIR-I) ranges of electromagnetic spectrum (ie, 400-700 and~700-1000 nm, respectively) is well characterized for most biological matters [5][6][7][8][9][10][11][12] including head [13][14][15][16][17] and brain [17][18][19][20][21]. NIR light has been found to better propagate through tissue than the visible one, and, in the beginning of 1980th, NIR-I region has been introduced by Parrish and Anderson as the diagnostic or therapeutic window [6,7].…”

“…The use of the fourth window at~2100 to 2300 nm has recently been suggested for soft tissues, such as skin [6][7][8], muscle [11], adipose [9,11,16] and internal organs [11,32,44], and also for brain in the recent study by Shi et al [18]. Therein, this spectral window centered at 2200 nm has been termed as NIR-IV window [18]. In the current article, we term it as SWIR-II, since SWIR is used more frequently in recent years [33,35,36], apparently due to a rapid progress in the development of the SWIR detectors [37,45].…”

“…In the current article, we term it as SWIR-II, since SWIR is used more frequently in recent years [33,35,36], apparently due to a rapid progress in the development of the SWIR detectors [37,45]. SWIR-II window demonstrate a promising potential for brain imaging in comparison with NIR-II one in terms of collimated/ballistic light permeability [16,18]. It was shown for skin and other soft tissues that light attenuation in SWIR-II region is comparable with that in NIR-I one, where tissues exhibit higher scattering [6][7][8][9][10][11].…”

Transmission of classically entangled beams through mouse brain tissue

“…In this case, the wavelength plays a key role for biological media; the scattering reduces as wavelength enters the NIR (690-900 nm) and in SWIR (1000-2500 nm). The optimum window in SWIR for deep imaging is the golden window (1600-1850 nm) in the brain [2].…”