Robust Wireless Interrogation of Fully-passive RLC Sensors

Fully passive sensors (FPS) are widely used as a simple and inexpensive alternative to their active counterparts in many applications such as implantable medical devices (IMDs), sensing in harsh environment (high temperature or corrosive media), and long-term non-destructive structural monitoring. Although for many of these applications short-range data communication (in the order of antenna dimensions) is sufficient, they disallow the use of active electronic circuitry and batteries to ensure robustness and maximize lifetime. Therefore, a fully passive sensor with the minimum number of components is preferred over the existing legacy sensors such as NFC, RFID, BLE, etc. Although great effort and progress has been made in developing such sensors, measurement of FPSs still relies on extremely bulky and complicated readers, preventing a practical sensing solution. In some cases, the readout method depends on measurement distance. In this talk, I will cover the conventional techniques for wireless interrogation of FPSs and introduce a readout technique based on a two-mode LC-oscillator formed with two coupled resonators, i.e., the FPS and the LC tank in the reader and show that it can offer distance-insensitive measurement of an FPS provided that the system operates under strong coupling. Speaker(s): Siavash Kananian, Virtual: https://events.vtools.ieee.org/m/299781