Select your own sensor and convert it into a wireless and battery-free sensor tag without any hardware development effort. No need to stick to the sensors featured in passive RFID sensor tags.
If you have been searching the market for a wireless and battery-free sensor you already know there are a small bunch of manufacturers that have some solutions in this area.
Even if some of these feature the right characteristics, chances are none of them are exactly what you are looking for. In general, each manufacturer has selected a sensor of their choice that is close to what you are looking for but not exactly it.
For all of you that have been looking at full passive RFID sensor tags (meaning wireless and battery-free sensors based on RFID technology), you can now develop your own. As explained in this previous post, the R-Meter converts any resistance dependent sensor into a battery-free sensor tag without any development effort.
Just select your sensor and attach it to the R-Meter. You will receive the resistance measurements in your RFID reader at your request. From then on, it is up to you how you want to develop your monitoring solution.
Accurate sensor data systems
All those systems thought to provide the user with accurate data will have to translate the resistance data to meaningful information.
Take thermistors for example. These sensors vary their resistance depending on the temperature they are at any time. The conversion from resistance values to temperature values is done according to generally accepted formulas. See thermistor product examples here.
Developing your own battery-free sensor system just requires you to use the formula that best converts the resistance data you get from your passive sensors to meaningful temperature data to display for the end user.
Qualitative sensor information systems
Your system may not require accurate data but just monitoring magnitude variations and the direction of those variations.
Think about a system detecting when a specific hole has been covered/uncovered by checking the ambient light level. The wireless and battery-free sensor system only needs to detect a resistance change big enough to associate to a ‘no light inside – hole has been covered’ state. See a light dependent sensor product example here.
In this case, no need to develop formulas at all, just select a good light dependent sensor, attach it to the R-Meter and detect resistance value variations in time.
As you can see, there is no reason to stick to a manufacturer’s sensor or transducer pick. Select your own transducer and build your wireless and battery-free sensor system without any development effort.