Merging bioelectrochemical transducer and antenna functions for continuous monitoring in biological tissues: an innovative volume-saving strategy

The continuous monitoring of physiological parameters can provide crucial information to better understand and treat health disorders more efficiently. However, because the size of implantable sensors remains generally too large, numerous parts of the body can still not be accessed. We propose here to combine in a synergistic way the two most volumetric functions of a typical sensing device, i.e. the energy supply and the communication unit, to reduce the overall device footprint. The electrode of a biofuel cell (BFC), whose role is to deliver DC current, is merged with the antenna electrode, whose function is to provide radiofrequency alternating current, transforming de facto the BFC electrode into an antenna. This first proof-of-concept BFC, acting at the same time as an energy source and an antenna, enables wireless communication of glucose concentration over macroscopic distances. A novel dielectric screening strategy is also proposed as a trade-off between the analyte diffusion (BFC function), and electric field preservation (wireless communication function) to optimize the overall efficiency. Finally, we demonstrate that the integrity of the proposed device can be maintained after subcutaneous implantation in rats. These results pave the way for wireless miniaturized implantable devices for continuous monitoring in biological tissues.