Systems are provided for a wireless system-on-chip (SoC) with integrated antenna, power harvesting, and biosensors. An illustrative SoC can have a dimension of 200 μm×200 μm×100 μm to allow painless injection. Such small device size is enabled by: a 13 μm×20 μm 1 nA current reference, optical clock recovery, low voltage inverting dc-dc to enable use of higher quantum efficiency diodes, on-chip resonant antenna, and an array-scanning reader.