This paper represents the extended version of the conference paper "Developing highly-integrated subcutaneous biochips for remote monitoring of human metabolism" presented at the IEEE Sensors Conference 2012, and presents data on assembly, packaging and short term in vitro and in vivo biocompatibility evaluation of a fully implantable biosensor array. The device was realized integrating three building blocks: 1) a multielectrode platform; 2) an inductive coil; and 3) an integrated circuit. The entire system measures 2.2 mm x 2.2 mm x 15 mm. Corrosion of electronic components and leaking of potentially hazardous substances in the body is prevented with a conformal coating of Parylene C, while an outer package of medical grade silicone was employed to create a soft shell suitable for implantation. Biocompatibility experiments did not show in vitro cytotoxicity in the considered period of 7 days, while comparison between 7 and 30 days in vivo implantations showed significant reduction of the inflammatory response in time, suggesting normal host recovery.