MEMS-Based Inductively Coupled RFID Transponder for Implantable Wireless Sensor Applications

• Published in: IEEE transactions on magnetics 2007-06, Vol.43 (6), p.2412-2414
• Main Authors: Lu, H.M., Goldsmith, C., Cauller, L., Jeong-Bong Lee
• Format: Article
• Language: English
• Subjects: Chips; Coiling; Coils; Cross-disciplinary physics: materials science; rheology; Electric potential; Exact sciences and technology; Implantable; Inductors; Magnetic cores; Magnetic resonance; Magnetic sensors; Magnetism; Materials science; MEMS; Micromechanical devices; Other topics in materials science; Physics; Radio frequency identification; Radiofrequency identification; Readers; RFID; sensor; Sensors; Solenoids; transponder; Transponders; Wireless sensor networks
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2007.893802

In this paper, we present the development of an inductively coupled mini RFID transponder using MEMS technology for implantable wireless sensor applications. The transponder (approximately 25 mm 3 in volume) consists of a small solenoid inductor with a high-permeability magnetic core (dia.=750 mum), a chip capacitor and a RFID chip. They are integrated onto a micromachined SU8 polymer substrate and it is operated in the frequency range of 13.56-27 MHz. Voltages up to 4 V were obtained at a small 0.5 muH transponder coil from a 2.2-muH reader coil at 5 mm distance based on a resonant magnetic coupling mechanism. The assembled transponder was tested using a commercial RFID reader at 13.56 MHz and successful communication was established at a distance of 10 mm.