TR181 SmartPads (for rats) and MT110 tBases (for mice) convert mains power into an electromagnetic field which passes harmlessly through non-metallic surfaces, such as the cage base and the skin of the animal. Telemeters have an inductor coil which converts the electromagnetic field back to electricity and subsequently powers the telemeter (Fig. 1).
It is important to ensure that the telemeter body is optimally positioned within the animal to facilitate continuous power transfer from the SmartPad or tBase to the telemeter. For rat telemeters the body of the telemeter should be secured in the abdominal cavity. For mouse telemeters the body of the telemeter should be in a subcutaneous pocket on the flank of the animal, between the limbs. More information on the implantation of telemeters can be found on the Support Section of ADInstruments website .
The electromagnetic power field has a range of 5cm and 7cm above the surface of the SmartPad and tBase, respectively. To ensure optimal power transfer we recommend that cage enrichment is limited to cylindrical or spherical shapes so that the rat or mouse is unable to sit on a raised platform above the cage base for a prolonged period of time.
Rat telemeters benefit from a back-up battery to ensure that recording continues, even if the rat moves outside the wireless power field of the SmartPad for between 4-6hrs depending on the telemeter model. This is useful for the continuity of day-to-day recording in the home cage but also supports behavioural experiments away from the home cage up to a range of 5m from the SmartPad. At the end of such experiments, the rat must be returned to the home cage placed within the power field of a SmartPad to allow the battery to recharge.