The purpose of this study was to develop a wireless microcontroller-based inductively coupled RFID (Radio Frequency Identification System) system to facilitate facile rat identification for modest scientific animal research. Rats, in particular, are difficult to identify because of their ability to scratch or chew off external tags and markings. Continuously replacing an animal's external tag assures increased handling and stress. Recent literature reports that stress can cause a temporary increase in blood pressure, heart rate, body temperature and plasma levels of epinephrine and norepinephrine  as well as influence ·an animal's response to phannaceuticals .
The RFID system developed in this project consists of a lightweight (half pound) hand-held reader and three passive microcontroller-based transponders (the transponders are encapsulated in epoxy to discourage body fluids from affecting their circuitry during in-vivo operation). The hand-held unit accomplishes transcutaneous power transfer via inductive coupling with a transponder. Without batteries, the transponders each have a long lifespan and can be made small (the transponders have an approximate diameter and thickness of 3cm and 0.7cm respectively). Following a successful read the hand-held unit displays an ID number on an LCD panel and notifies the user via an audible alert.
System tests included: power and voltage transfer characterization, modulation analysis, coil-coil misalignment tolerance, thermal testing and an in-vivo study with three Sprage Dawlyrats. The system operates at 5.65MHz, has an overall power consumption of 521mW, and transmits data via QSK at 40bits/sec over a range of approximately 2.54cm. The system will operate continuously for 10-11 Y2 hours with a 9V battery supply. In-vivo testing resulted in successful identification over a range of 1.5-2.5cm.