Smart Floating Balls: 3D Printed Spherical Antennas and Sensors for Water Quality Monitoring

This paper proposes a novel additively manufactured floating ball sensor for water monitoring applications. A chipless RFID phase modulation configuration is used along with spherical patch antennas and phase delay microstriplines that are sensitive to the liquid content. The spherical patch antenna array provides omni-directional gain in water level plane and can be used in MIMO applications in the water. The phase delay line utilizes a microfluidic channel embedded into the microstripline so that the phase introduced by the line can be reconfigured by the liquid inside the channel. Due to its complex shape, the floating ball fabrication process combines both 3D printing and 3D stamping, which enables selective 3D metalization using the same platform. The smart floating ball can monitor reservoir water quality while preserving its original function as a "shadow ball" featuring low-cost, light-weight and battery-less, which are important features for massively scalable "smart" systems.