Design of a programmable temperature monitoring device for tagging small fish

This paper describes the design of an archival temperature monitoring tag to be used to collect habitat information of Atlantic salmon during the marine phase of the species´ natural history. The monolithic circuit should not exceed an average power dissipation of 5 μW so that a small 3 V lithium battery of 50 mAh charge will provide the device with the expected lifetime of 3 years. The thermal sensor is realized by a pn-junction. The recorded junction voltages are digitized and stored in static RAM cells. Upon retrieval of the tag, the stored temperature values will be transferred to a computer where the geographical location of the fish at the actual sampling time will be deduced through retrospective navigation based on known sea temperature distribution