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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.

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    \$\begingroup\$ What's wrong with wires over a distance of 2-3 metres? The cost of the wire will be comparable to the cost of the thermistor. Or did you mean miles? \$\endgroup\$ – Neil_UK May 19 '20 at 12:42
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    \$\begingroup\$ using a battery in the sensor chip Show me an example where there's a battery inside a chip. Perhaps you mean battery inside your sensor product (case). My guess is that you will need a battery in your sensor product. There are batteries with a 10 year lifetime guarantee. Also a circuit that does the measurement and sends out the data which will last years on one battery is possible (as long as you don't want the data too often). The reinforced concrete might be an issue as it absorbs/reflects/blocks radio signals. \$\endgroup\$ – Bimpelrekkie May 19 '20 at 12:44
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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 assuming you mean miles and not metres here! Also RFID will never work as you describe it.

Engineer a data collection system (you can buy one of course) and all your temperature sensor voltages are digitized and converted into one big digital frame of data to be sent (via coax or twisted pair) to where you want to receive that data. At that place you would need to recover the data into the individual channels and convert back to analogue.

This type of product is commercially available. You could power the data collection system locally from recoverable batteries or use a regular AC supply if available. You could even use radio to transmit the frame of data. Given that the cost is in the equipment and not the sensors in the concrete, that cost is re-usable for the next structure you build/test.

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