Body surface backed flexible antennas and 3D Si-level integrated wireless sensor nodes for 17 GHz wireless body area networks

Wireless sensor nodes placed on the body should for natural reasons be small and inconspicuous. A 17 GHz radio gives the highest data throughput per Joule, and enables significant size reduction compared to commonly used lower frequencies. A wireless solution at 17 GHz is proposed for WBAN sensor applications, making use of 3D stacking, vertical connections integrated on Si-level, as well as antennas suitable for 17 GHz. The presented antennas are fabricated on 100 um thick polyimide flexible laminates. They are studied numerically and experimentally, both in free space and on real body surface, with respect to body surface wave propagations and radiation off the body surface. Body effects on antenna impedance and radiation performance are also studied. The wireless 17 GHz sensor node electronic architecture makes use of a tight integration of mixed technologies for 3D accelerometer sensor with ADC, processor, and transmitter. All these modules are incorporated in a 3D Si-stack. The node also includes a power management block.