The skin is permeable to near-infrared light (NIR).
Nevertheless, several studies with NIR dyes have been done, Prof. Pickup with Dr David Birch made a NIR sensor measuring both the time-resolved counts or by nanotomography of allophycocyanin-ConA/malachite green-Dextran,[REF][REF][REF][REF] where allophycocyanin is a NIR fluorescent protein [REF].