Understanding the behavior of free-living marine organisms is pivotal for many conservation efforts (REF) and examining how to change, such as overfishing and climate variability, affect marine ecosystems 1. For this, many researchers have turned to animal-attached tag technology 2 where study animals carry archival “smartâ€ tags that record a suite of parameters to quantify particular aspects of their behavioral ecology or physiology. It was demonstrated that the Pelagic jellyfish blooms are increasing worldwide as a potential response to climate change. The results shown in 3 suggest an enhanced growth of the jellyfish in response to global warming, whereas low temperatures may set the limits for successful invasion of the jellyfish into colder water bodies.
Therefore, we are developing an underwater reliable wireless marine monitoring system composed of a flexible magnet (NdFeB-PDMS) and an MTJ-based sensor as shown in Fig. 1 in order to count the number of the jellyfish contractions under different environmental conditions. The fabrication process of the NdFeB-PDMS composite magnet involves minimal complexity, has lower cost, and is highly versatile with respect to the shape of the magnets 4 which play the role of a monitor of any jellyfish movement that would be detected by our MTJ-based sensor over time as can be seen in Fig 2. The composite magnet is coated with Paralyne C to protect the composite from degradation, make the remanent magnetization constant, and provide resistance against corrosion and biofouling, flexibility, and biocompatibility. The results show the suitability of the composite magnets for marine applications. Our results provide a framework for understanding the physiological tolerance of Cassiopea under possible future climate changes, which can be better interpreted by statistical coming studies using a wireless marine monitoring system based on our MTJ sensors.