Looking at Skin Temperature

During my individual meeting with our teachers last week discussing my research project, we talked about what kinds of possible inputs my wearable could be measuring in order to maximize accuracy and visual/conceptual interest of the final output. This has also got me thinking about what exactly are the things I should be measuring. The first and probably most important one is skin temperature.

It turns out, as one might expect, that there are a number of different internal and environmental factors that end up affecting skin temperature. There are two main things you have to take into account: ambient temperature and core body temperature. Also, even taking those two factors into account, different parts of the body will have different skin temperatures even with the same ambient and core temperatures. I found this article to be very helpful, and they had this extremely useful graph that illustrates the skin temperature discrepancies on various parts of the body:

facts_1

Some other useful bits of information from that article:

“…your skin temperature varies parabolically from 83 deg F. (28.2 C) at an ambient temperature of 49 deg F. (9.5 C) to 98 deg F. (37.2 C) at an ambient temperature of 95 deg F (35 C).” Dr. K.R. Koehler College Physics for Students of Biology and Chemistry, University of Cincinnati

“Skin is the principal organ for dissipating heat: the human body dissipates
approximately 85% of its heat loss through the skin under normal environmental
conditions (Zhang 2003).”
Holopainen, R., A human thermal model for improved thermal comfort, Doctor of Science in Technology Thesis, Aalto University, VTT, December 2012

Based on the second quote above, another factor that would possibly need to be taken into account is the temperature change created by the fact that the parts of the skin I’d be measuring would be covered by knit gloves, which are obviously going to help with trapping the heat.

I think I also need to consider what environments I’m expecting this item to be worn in. For instance, if this is a general wearable for anywhere indoors or outside, I need to consider the normal range of outside temperatures that I should be measuring within (probably just based on a normal Baltimore climate as there’s simply too great a variation of climate based on geographic location, although if it was possible to program different temperature ranges for different climates, that would be ideal; maybe even adding a GPS component in that can determine automatically what the local climate of the location you are in is). However, if it’s just going to be mainly an indoors wearable, I need to look into what is considered a general range of comfortable indoor temperatures (which would be a much shorter temperature range than that of outdoors, obviously). I want to maximize my range of possible inputs while keeping them realistically narrow enough to get the broadest possible output range on the LEDs. That is to say, if one of my inputs is set to measure outside temperature anywhere from, say, 0°-100° F, and each value within that range is programmed to correspond to a slightly different color within the range of an RGB LED, but because of where the piece is generally ever worn, it’s really only getting a range of temperature inputs from, say, 65°-80°, instead of getting that wonderful full range of possible colors, you’d end up only ever seeing perhaps a slightly varying range of oranges. Likewise, I don’t want to set the input range to be so narrow that the piece is ultimately ending up missing a bunch of information, and tends to easily hit the bottom or top of its measurement range super easily and get stuck there because it can’t read the higher or lower inputs happening around it.

This was another website I found with what seems like some relevant information.

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