Modification and miniaturization of Thermochron iButtons for surgical implantation into small animals
- 692 Downloads
Thermochron iButtons are being used increasingly by animal physiologists to measure long-term patterns of body temperature in reptiles, birds and mammals. Typically, iButtons are surgically implanted into the intraperitoneal cavity where they measure and store body temperature together with the date and time from an onboard real-time clock. In 16-bit resolution, the DS1922L iButton can store a total of 4,096 data points over pre-determined sampling intervals. iButtons have proved invaluable in measuring patterns of torpor and hibernation in animals larger than 70 g. Weighing around 3.5 g after potting with wax, iButtons are too heavy and large to implant into animals smaller than 70 g because their weight exceeds 5% of the animal’s total body weight. This paper describes how the stainless steel canister housing the DS 1922L iButton battery and circuit board can be removed to reduce the weight of the components to 1.49 g after waxing (ready for implantation) without compromising the function or battery life of the iButton. The modified iButton can be implanted into animals as small as 20–30 g. Calibration data revealed an offset of ca. 1°C on average, confirming that iButtons must be calibrated prior to implantation.
KeywordsThermochron iButton Body temperature Aethomys Rhabdomys
This research was financed by publications incentive grants from the University of KwaZulu-Natal Research Office. I am grateful to Mark Brown for assistance with maintaining the research animals, and Kerrileigh Lobban for assistance with surgery. Steve Johnson kindly took the photographs.
- Mzilikazi N, Lovegrove BG, Masters JC (2004) No evidence for torpor in a small African mainland primate: the lesser bushbaby, Galago moholi. In: Barnes BM, Carey HV (eds) Life in the cold: evolution, mechanisms, adaptation and application. Twelfth International Hibernation Symposium. Institute of Arctic Biology, Fairbanks, pp 29–40Google Scholar
- Robert KA, Thompson MB (2003) Reconstructing Thermochron iButtons to reduce size and weight as a new technique in the study of small animal thermal biology. Herpetol Rev 34:130–132Google Scholar
- Skinner JD, Chimimba CT (2005) Mammals of the Southern African Sub-region. Cambridge University Press, CambridgeGoogle Scholar