System for Testing RFID Tags’ Ability to Sense Humidity

Author: Brett Stoddard

Hello  Everyone! 

For the past few weeks, I’ve been further examining the RFID Dogbone Tags. This time I’m testing their capability as capacitive humidity sensors. This article describes the system I built to test them out.

Abstract and Objectives

This blog post describes a system to log data from multiple Smartrac Dogbone RFID moisture sensing tags in the air over the course of the day. The goal of this system is to log the Dogbone’s moisture sensor levels vs a DHT11 Humidity and Temperature sensor. After logging data for multiple day cycles, enough data should be present to tell if there is a relationship strong enough between the Dogbone’s measurements and the DHT11. Further testing would be warranted if such a relationship exists.

To measure multiple tags at once, this system incorporates a HyperRail prototype. The HyperRail’s details can be found distributed throughout this blog page on the OPEnS site.






Over the weekend the system was run. It gathered some data, but not enough to make a sure prediction of whether the Dogbone tags can be used as humidity sensors. However, this is an example of what the code output should look like.

Values of RFID, Humidity, temp, EPC, time, f

What data should look like when opened in Excel

Known Issues

As of now, the SD card will only log data when the Arduino is plugged into both USB. This shouldn’t be necessary because it is already powered by Vin. This issue is probably a power supply limitation of my specific setup, however, I thought it was worth noting here.