In-vivo cell and tissue monitoring with active implants

Active implant systems are becoming increasingly important in modern medicine. We describe the development of an implantable system for the monitoring of dissolved oxygen. Tissue oxygen saturation plays a leading role in many pathophysiological processes in the human body such as the growth of malignant tumors or the viability of transplanted organs. The implant allows monitoring the tissue oxygenation in vivo with a wireless interface to an external device. An improved self-calibration technique is described to minimize sensor drift with electrochemical sensors in vivo for a better long term stability of the implant system. The sensor was coated with a hydrogel membrane to avoid convection artifacts during calibration procedure.