Semi-Passive RFID Electronic Devices With On-Chip Sensor Fusion Capabilities for Motion Capture and Biomechanical Analysis

This article presents the development and testing of a novel electronic device for wireless motion capture (W-MoCap), a technology that allows the reconstruction of movements of objects and body parts with many potential applications in various contexts. The device integrates UHF radio frequency identification (RFID) technology with sensors for low-power backscattering communication. It consists of a battery-assisted passive (BAP) UHF RFID chip, an inertial measurement unit (IMU), an ultralow power microcontroller, and a custom-designed edge-fed body-tolerant antenna operating at 866 MHz. The proper matching between the RFID chip and antenna is ensured through a well-designed L-match unbalanced network, and the separation of RF and dc signals is achieved with a meandered microstrip quarter-wavelength transformer, choke inductor, and decoupling capacitor. The designed and realized RFID W-MoCap sensor tag has been thoroughly evaluated in terms of current consumption, front-end sensitivity, and sensing accuracy. Finally, five prototypes have been applied to specific segments of a human subject and successfully tested in a practical scenario for real-time reconstruction of human movements.