I'm currently working on an RFID wearable wristband concept. The goal is, to use a 860–960 MHz UHF RFID Chip and detect people wearing the wristband over a few meters. I created a physical wristband and embedded the Chips in there (see below). It also contains several other parts (13,56 MHz Chip, power coil, vibration motor...), but this isn't important for this problem.
The system works... kind of. When holding the wristband in the hand or placing it somewhere, the UHF detection works via antenna and Arduino over several meters. But as soon as the wristband is put on the wrist and is in close contact with the skin, the detection stops immediately.
So I started investigating, and it seems like the nature of the human skin and body is the problem. This isn't a very well researched topic, but according to a few sources, the human body absorbs or reflects signals like the ones I try to send and read. Apparently the moisture and the salinity of the skin influences the effect heavily. That also explains, why the problem wasn't as devastating when I tested it a few days ago (when it was cooler and I wore longer cloths). It's a similar problem as placing RFID tags on metal.
I tried placing different materials between the tag and the skin to further isolate it, but until now only a physical distance of a few centimeters worked. Since the wearable can't just be 10 centimeters thick to create the gap, this isn't really an option. I checked out the very few available UHF wristbands, and most of them use some kind of distance separator, like spikes or foam pads. I added foam pads to mine too, but this only optimized the recognition within 30 centimeters of the reader, but didn't enable the desired detection within meters.
Does anybody already had some experience with this phenomena and knows a solution? I don't think I need an Arduino-Exlert, I more likely need a RFID-Expert/Physicist. I'm working on this project for a year now (on and off) and it came along really great, but this feels like a dead end.