Further miniaturisation of the Thermochron iButton to create a thermal bio-logger weighing 0.3 g

Abstract

Thermochron iButtons are commonly used by thermal biologists to continuously measure body temperature from animals. However, if unmodified, these devices are of a size that limits their use with very small animals. To allow iButtons to be used to study smaller species, methods to miniaturise them by 61% have been previously described. We present a method to reduce iButton mass by a further 71%. The modified devices have a shorter battery life, but the minimum size of vertebrates able to carry the devices is reduced from 28.9 g to 6.6 g, if the arbitrary, yet widely cited, maximum of 5% body mass for attached devices is adhered to. We demonstrate the application of our method by recording surface temperatures of captive and wild skinks and show that captive cockroaches weighing 0.8 g are also able to carry the device. We believe this to be the first time that temperature data have been recorded from an insect in this way.

The thermal ecology and physiology of reptiles and amphibians: A user's guide

“…iButtons are typically used to study animals that are large enough such that the data‐logger mass (3.5 g after dipping in sealant) along with the radio‐transmitter mass if present are together <5% of the animal. However, several groups have recently developed methods to miniaturize iButtons (Lovegrove, 2009; Robert & Thompson, 2003; Virens & Cree, 2018) to as low as 0.3 g such that they can reasonably be attached to animals as small as 6.6 g. When properly coated, these miniaturized iButtons can also be surgically implanted to collect internal T b from small animals, such as lizards (Rusch & Angilletta, 2017; Sears et al, 2016). For very large animals, like crocodilians and some turtles, lizards, and snakes, it is possible to attach or implant larger data loggers like Onset HOBO Tidbit data loggers (e.g., Fitzgerald & Nelson, 2011; Harlow, Purwandana, Jessop, & Phillips, 2010; Merchant, Williams, Trosclair, Elsey, & Millsa, 2007; Wolf, Walters, Rochford, Snow, & Mazzotti, 2016).…”

Technology wish lists and the significance of temperature-sensing wildlife telemetry

“…While some researchers actually engineer their own transmitters or other equipment, others modify existing technology. One example of this is user-modifications to reduce the size and weight of Thermochron iButton temperature loggers, which are often used with telemetry for thermal ecology studies [27][28][29]. In addition, for two of the most prevalent telemetry equipment problems-data download and battery life-survey respondents proposed potential fixes using drones and rechargeability.…”

Extending the biologging revolution to amphibians: Implantation, extraction, and validation of miniature temperature loggers

“…However, such miniaturization requires substantial technical skills, testing and validation, and subsequent modifications for implantation (Lovegrove, 2009). Some modifications can reduce battery life (Virens & Cree, 2018), while others add weight to the logger (Lovegrove, 2009). Alternative approaches for small ectotherms have involved implanting temperature‐dependent radiotransmitters (e.g., Wang & Adolph, 1995), an approach that can be limited by short battery life (e.g., a few weeks or months) and yields only point samples which can bias inferences about thermal ecology (Taylor et al, 2004) without the constant presence of a human observer and receiver, or installation of automated receiver arrays (Beaupre & Beaupre, 1994; Smits, 1984).…”

“…Environmental temperature loggers such as Thermochron iButtons (Maxim Integrated) or Hobo TidBiTs (Onset Computer Corporation) have been implanted in medium-to-large amphibians and reptiles such as Rhinella (Noronha- de-Souza et al, 2015). Modification of iButtons to reduce mass and size has facilitated implantable temperature logging in small animals across a broad taxonomic range, for example, cockroaches, skinks, mice (Lovegrove, 2009;Virens & Cree, 2018). However, such miniaturization requires substantial technical skills, testing and validation, and subsequent modifications for implantation (Lovegrove, 2009).…”