Reminds me of something long ago called Kirilian photography or some such.
Kirlian photography has to do with the coronal discharge patterns exhibited by various objects, both inert (like coins) and living (like leaves and human body parts). It's an interesting phenomenon, but has also been associated with various paranormal activities and beliefs which are for the most part debunked and/or garbage.
I worked with physicists doing Kirlian photography in the 1970's when it was very popular and hip in research circles. It was interesting, but nothing like it was hyped up to be.
In any case, it's not in any way related to the heat produced by the body as a result of normal metabolism, which is the topic of this breathless and rather overblown article.