In this paper, we report the development, evaluation, and application of ultra-small low-power wireless sensor nodes for advancing animal husbandry, as well as for innovation of medical technologies. A radio frequency identification (RFID) chip with hybrid interface and neglectable power consumption was introduced to enable switching of ON/OFF and measurement mode after implantation. A wireless power transmission system with a maximum efficiency of 70% and an access distance of up to 5 cm was developed to allow the sensor node to survive for a duration of several weeks from a few minutes’ remote charge. The results of field tests using laboratory mice and a cow indicated the high accuracy of the collected biological data and bio-compatibility of the package. As a result of extensive application of the above technologies, a fully solid wireless pH sensor and a surgical navigation system using artificial magnetic field and a 3D MEMS magnetic sensor are introduced in this paper, and the preliminary experimental results are presented and discussed.
Photos of the first prototype sensor node and second prototype sensor node before (a,c) and after packaging (b,d) using the 3D-printed case, and then covering and filling with bio-compatible soft-gel. (credits: Jian Lu, Lan Zhang, Dapeng Zhang, Sohei Matsumoto, Hiroshi Hiroshima, Ryutaro Maeda, Mizuho Sato, Atsushi Toyoda, Takafumi Gotoh and Nobuhiro Ohkohchi)