Upper-bound performance of Laser-Induced Graphene (LIG) antennas on PEEK for implantable applications

Laser-Induced Graphene (LIG) can potentially boost the development of smart prostheses by engraving an antenna on a polymeric precursor without any additional material and structural modification of the implant. A commonly used polymer material in implantable prostheses is the Poly-Ether-Ether-Ketone (PEEK) due to its biocompatibility, mechanical strength, and low weight. This paper experimentally characterizes the electrical features of LIG traces on PEEK with the purpose to identify the upper-bound radiation performance of a reference implanted loop of optimal size by numerical simulations based on measured values of sheet resistance of PEEK samples that have been laser-engraved with different settings. Results revealed that in the case of the lowest sheet resistance (R3=5Ω/ □) the maximum gain is just 3 dB lower w.r.t. a reference copper antenna, thus making the concept of engraved prostheses feasible.