The Thelma Biotel temperature sensor is a low-power and versatile platform for temperature measurements alone, or in combination with other suitable sensors. It can be measured over a wide span from -20 to 50 °C and can be made to present high resolution in any range of interest. The transmitter is produced in five different transmitter sizes and with a wide range of battery packs, allowing optimization in size and operational life.


  • Available in all transmitter sizes 6, 7, 9, 13 and 16
  • Long operational lifetime ~ 3 months – > 10 years

The transmitter measures the temperature using an embedded, high – precision digital sensor. When the transmitter is implanted, the animal’s experienced temperature is measured.

Thelma Biotel offers the smallest temperature sensor acoustic transmitters on the market. It can be delivered down to 6.3 mm in combination with other sensors, such as depth and acceleration, with several months of operational lifetime.

Picture: 9 mm transmitters


The temperature sensor is highly applicable alone or in combination with other sensor options. The temperature sensor provides the tagged animal’s experienced temperature. This information allows you to track mammal predation and look at temperature differences in diverse water masses and depths where the animal resides. One version of the temperature sensor can measure the accumulation of day degrees over time as a direct output.


The standard measurement for temperature is a point measurement taken right before the data is transmitted. This means that the measurement frequency will be linked to the transmit interval. Always check your delivery note to ensure you apply the correct calculation when converting measurement data to the unit of choice. The method may vary due to different data ranges and setups.


There is a variation of measurement modes available upon request. For example, a trigger at specific temperatures for a change in ID when exposed to temperatures above/below a baseline for mammal predation tracking.

The transmitter can also be made to measure day – degrees as a direct output in addition to the temperature values. In the latter instance, the measurement mode will be an accumulation of temperature over time rather than a point measurement.

Do not hesitate to contact us for more information regarding your project.


The temperature sensor can be produced with a set of different temperature range alternatives to match the required maximum temperature, resolution needs, and the transmit protocol used. The standard and most commonly used temperature range is 0 – 25,5 °C. Most sensor data transmit protocols have 8 bits or 0-255 points resolution, where these points of resolution need to be distributed over the relevant temperature range to be measured. The OPs protocol carries a data value of 0 – 4095 points span, so it can be delivered as 0.1 resolution all the way from – 20 to 150 °C. This is currently handled as special production and will require some added production time.