Microsensors and -actuators for medical applications have been under research for decades. For in vivo applications longterm stability is a critical prerequisite. Reliable, continuous and economical in vivo monitoring (glucose, blood gases and ionic analytes) or in vivo agent dispensing still remains an unsolved problem, mainly due to host response towards the implant and instability of sensor components. In order to assess tissue response towards implants and biocoatings we propose continuous measurements at the implant/tissue interface employing a microsensor device placed in contact with the chorioallantoic membrane (CAM-Assay) of the avian embryo.
We introduce an electrochemical microsensor array and a miniaturized potentiostat unit (“MiniPot”) to measure oxygen, pH and electrical impedance in situ. Oxygen sensor performance showed a sensitivity of 3,31 – 12,8 nA / mg/l and response time ranging from 10s – 250s. pH measurements showed linear behavior (-73,2 mV/pH) between pH 4-10. Overall, all sensors showed significant absolute values, confirming reproducibility in fabrication. We evaluated the CAMAssay of avian ex ovo cultures. Here, we established an immune-active and -deficient in vivo model, enabling comparison between either weak or strong immune responses in the same organism, respectively. Measurements were performed in an incubated biological environment. We consider this model to be a useful tool to evaluate future developments of biofunctional coatings and implants in a quasi-in vivo environment to promote research of implantable biosensors and -actuators.