Project Image:
Title of the project:
Microsensor implant for in vivo monitoring of the ingrowth behavior of functional biomaterials
Microsensor implant continuously monitors tissue reaction after implantation of biomaterial in egg model
Project leader:
Dr. Martin Stelzle
Project funding:
  • Bundesministerium für Bildung und Forschung (BMBF)
Project management:
  • VDI/VDE Innovation+Technik GmbH
Funding reference number:

The long-term goal is implantable, functionally ingrowing sensors with high long-term stability. A microsensor implant with several electrochemical microsensors is being developed for this purpose. The implant is coated with bioactive material and implanted in an animal model. The continuous monitoring of the sensor data allows conclusions to be drawn about the course of the tissue reaction. In incubated chicken eggs, the correlation between physical parameters and the physiological state of the tissue around the implant is first determined in detail. The aim is to establish ImplantMonitor as a test system for new coating materials that also requires less animal testing.


Medical and microsystems technology make it possible to develop completely new types of implants. Tissue reactions after implantation represent a central challenge. For sensory implants, for example, it is extremely important that they are not affected by regenerative tissue.
can be encapsulated. Scar tissue around the implant impedes the access of analytes to the sensor, which leads to an unacceptable drift of the sensor signal.
Despite the great demand, there are no implantable glucose sensors with a long service life. Bioactive coatings promise a way out. With them, the implant can grow in without losing its functionality. However, newly developed biomaterials must be characterised both in vitro and in vivo before they can be used in a medical product. However, animal experiments are still required to assess the tissue that grows around the sensor as a result of the foreign body reaction. In most cases, however, only histological examinations are evaluated at the end of the test phase. To date, there is no system that can continuously monitor the tissue reaction after implantation of a biomaterial.
This is the aim of the ImplantMonitor project. This microsensor array (MSI) continuously measures dissolved oxygen, pH and electrical impedance and thus the diffusive and physical properties of the implant/tissue interface. The microsensors are manufactured on polymer and glass substrates using thin film technology, microelectroplating and microdispensing technology.
The chorioallantoic membrane (CAM) of chicken embryos in Petri dishes serves as a quasi-in-vivo environment. These serve as a model showing foreign body reactions to microimplants.
For this purpose, the MSI is coated with biomaterial. Its measurement signals are compared with those of an uncoated MSI. Both MSIs are implanted on the same CAM, so that the difference signal allows direct statements about the ingrowth behavior of the biomaterial coating. Biodegradable and biostable coatings are used to induce different ingrowth behaviour, to measure the characteristic sensor signals and to correlate them with histological examinations after explantation.
This correlation of continuously recorded sensor data with histological examinations is a step towards a "quantification of biocompatibility". The MSI complements the known histological methods and should support and accelerate the development of new biomaterials and coatings.