The objective of ImplantSens was to empower the next generation of scientists and entrepreneurs with multi-disciplinary training in the research area of implantable biosensors, a topic of fundamental interest for the future of Europe. Accurate, long-term in vivo measurements of bio-analytes such as glucose remain a until-now not solved challenge due to the hostile environment the body creates for any implanted foreign body. Device implantation triggers a cascade of inflammatory responses in the body as it responds to the presence of the implanted sensor. In the final stage of this response, the implant becomes encapsulated by a vascular and collagenous capsule which leads to the gradual loss of the function of the implanted biosensor and, most importantly, to a constant modulation of the diffusional flux of the analyte towards the sensor surface.
A biosensor usually comprises an active sensor layer, consisting of one or more enzymes producing a terminal product that can be detected at the chosen transducer. The generated signal depends on the amount and activity of the immobilized enzyme and the concentration of the analyte at the site of the enzyme which, in turn, is a function of the concentration gradient between the analyte reservoir and sensor compartment as well as the diffusional mass transport towards the sensing layer. This diffusional mass transport is modulated by the formation of additional semi-permeable layers such as the encapsulation layers formed by the foreign body response. The signal will decrease over time due to the inevitable changes in the mass transport properties of all the layers separating the sensor compartment from the analyte reservoir.
Hence, the ultimate question that had to be addressed by the 11 ESRs of ImplantSens is: How is it possible to measure the analyte concentration within the sensor compartment under conditions such that the concentration gradient is equilibrated and no net diffusional flux occurs?
The beneficiaries of the consortium consisted of 11 internationally recognized research groups and industrial partners from 7 European countries. In building this consortium complementary scientific excellence was essential to provide the required interdisciplinary basis to solve the inherent problems encountered in developing long-term stable implantable electrochemical biosensors.
The research program was divided into 7 work packages that defined overarching scientific questions with cross-disciplinary participation of the ESRs to provide a broad scientific training program. The network offered a sophisticated additional training program based on a blended learning concept composed of local, network, and e-learning elements which is far beyond what is typically offered in a graduate program at a university. The technical and scientific training was complemented with comprehensive training in science communication, effective public engagement, creative thinking, entrepreneurship, and self-development to enable the exploitation of the scientific output while guaranteeing wide dissemination of the generated knowledge as well as preparing the fellows for future challenges.
