Tachographs for diving animals

Feelings run deep when whales are stranded on the beach or when seals perish in an epidemic. Therefore, marine biologists also measure their diving behavior and eating habits - with the help of a miniaturized electronic recorder strapped to the animals' backs.

Seals, sea lions and penguins have two things in common with whales and dolphins: They are all ocean swimmers and evoke human sympathy - not only from children. Especially when whales become stranded or seals fall victim to an epidemic, some of us ask: How did this happen? Could this be prevented in future? The job of answering such questions lies with marine biology researchers, thus the creation of BioMar. This three-year project, initiated by the German Federal Ministry of Education and Research as part of the Microsystems Technology 2000+ program ended recently. Its aim was to record the living habits and movements of ocean animals using miniaturized electronic devices.
One such device - a tachograph smaller than a pack of cigarettes - was developed by the firm Driesen + Kern GmbH based in Schleswig-Holstein. Above all, it had to be small, recalls company founder Hermann Driesen. The more compact the device, the smaller animals can be investigated without hindering its movements. Despite our experience with measuring devices, here we were pushing the limits of how many miniaturized components we can combine in the device. One of the seven project partners was in a position to help: The Fraunhofer Institute for Reliability and Microintegration IZM in Berlin. The electronic brain inside the pressure-resistant, streamlined titanium capsule is multi-talented, emphasizes Dr. Klaus-Dieter Lang, head of the IZM branch lab Microsystems Engineering. It is capable of measuring an abundance of variables that the zoologists can use to record swim behaviors and other characteristics. The electronic circuits used to record and store the data are correspondingly complex. A tiny gyrocompass and a series of pressure sensors map the swim profile in every direction. Water quality measurements such as oxygen content, electrical conductivity, temperature and pH values are also taken. In combination with a light sensor, researchers can also determine where and when the animals feed - day or night?
The device is still limited to operating at a depth of 200 meters. However, a new model is under development: Filled with almost incompressible silicon oil, it will also record the diving characteristics and migration habits of large whales. Collecting the devices should also be simpler. When the data storage is full, the tachograph burns through its own retention line and rises to the ocean surface. It then sends its GPS coordinates via radio signal, enabling the researchers to easily locate and retrieve the device.
For further information:,Dr. Klaus-Dieter Lang ,Telefon: +49 30 / 63 92-81 79 ,Fax: +49 30 / 63 92-81 62 ,E-mail: [e-mail]
Dr. Martin Schneider- Ramelow ,Telefon: +49 30 / 4 64 03-1 72 ,Fax: +49 30 / 4 64 03-1 62 ,[e-mail]
Fraunhofer-Institut fur Zuverlassigkeit und Mikrointegration IZM ,Gustav-Meyer-Allee 25 ,Gebaude 17 ,D-13355 Berlin ,http://www.pb.izm.fhg.de/izm/index.html
Dipl.-Phys. Hermann Driesen ,Telefon: +49 41 92 / 98 14 ,Fax: +49 41 92 / 73 21 ,E-mail: [e-mail]
Links: ,VDI / VDE: Projekt Biomar (pdf) ,http://www.vdivde-it.de/mst/foerderung/verbuende/1999/biomar.pdf ,Driesen + Kern GmbH ,http://www.driesen-kern.de/

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