Transmission reliability of implantable wireless temperature loggers for laboratory rats

This paper presents a solution to enhance successful transmissions from an implantable temperature measurement device in laboratory rats and this solution is supported with in vivo measurements. When monitoring group-housed rats moving freely inside a cage the transmission pattern of the miniaturized implanted telemetry loggers changes constantly with time. A measurement system consisting of a low-power implantable telemetry temperature sensor with a transmitter along with a separate receiver with an antenna located under the cage is described. Telemetry loggers were implanted into the abdominal cavity via a minimally invasive surgery of less than 10min on average while the rats were under anesthesia. Different package transmission schemes are compared to establish an optimal transmission method with an average 98.4% reliability of transmission from the in vivo experiments. The transmission power and pattern of the telemetry system is evaluated in free space conditions and compared to the throughput of the in vivo measurements.