Split Ring Resonator Inspired Passive UHF RFID Antenna System For Wireless Intra-Abdominal Pressure Sensor

We present a passive UHF RFID tag based on a spatially distributed split ring resonator antenna system. The physically separated parts of the tag form a remotely detectable platform, which can be partly implantable and partly wearable. This is the first stage in our research toward a RFID-inspired wireless intra-abdominal pressure sensor. The tag consists of a wearable split ring and a small implanted split ring resonator carrying the RFID microsystem. In our experiments, the tag is detectable at a distance of 1 m with a 10 mm implant depth and 0.3 m with a 30 mm implant depth. Our results also show that the tag tolerates a rotational misalignment up to 45° between the implanted and wearable parts without severe performance deterioration.