These units are designed as intraperitoneal implantation in snakes and lizards. When fitted with a temperature sensor, the pulse rate is adjusted to accommodate the wide body temperature range of poikilotherms. For other applications the pulse rate can be set to measure narrower temperature ranges. These units can also be configured for use in waterfowl and mammals.


Model Weight Standard Life Lifespan range Dimensions: L x Diameter (mm)
SI-2 9g 12 months 6-18 months 33 x 11
SI-2 11g 18 months 12-24 months 40 x 11
SI-2 13g 24 months 12-30 months 50 x 11

Frequency Range: 138 – 235 MHz.

Transmitter: Crystal controlled two-stage design pulsed by a CMOS multivibrator.

Pulse Width (standard): 24 milliseconds.

Pulse Rate (standard): 35 pulses per minute (ppm). Available from 20-120ppm.

Power Output: Set to use available battery power over the required transmitter life.

Activation: Removing an external magnet starts the transmitter. Replacing the magnet stops the transmitter.

Housing: The battery and transmitter are hermetically sealed in a brass case. A small groove is added to the unit to allow for suturing during implantation. To prevent tissue reactions, the case is coated with multiple layers of a biologically inert butyl rubber compound. For subcutaneous placement, asymmetrically tapered ends can be added, increasing the length by 5mm at each end.

Antenna: Finely stranded stainless steel cable, covered with a clear Teflon coating. Clear silicone tubing reinforces the base.


Temperature (suffix “T”): An increase or decrease in temperature results in a corresponding increase or decrease in pulse rate. At the standard settings, the pulse rate changes from ~15 ppm at 0°C to ~40 ppm at 40°C. Each transmitter is supplied with a plotted calibration curve. This option adds ~0.05g to the finished weight of the transmitter.



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