What I'd want to do is to use cheap disposable temperature sensors and to read the temperature data wirelessly. The sensors would be set in a medium such as reinforced concrete. Right now I'm using wired thermistors, but since I need to read the data from a range of 2-3m then eventually the wire cost would get fairly large.
I've looked into passive RFID tags, but as I understand it, one would need expensive equipment in order to reach such a distance. Now my question is that are there any alternatives to RFID that would reach a range of 2-3m and would be cheaper to implement. I'm not really keen on using a battery in the sensor chip as they wouldn't be recovered after the experiments.