After cochlear implant (CI) insertion, there is a possibility of postoperative inflammation, which may involve proinflammatory markers such as interleukin-6. Detecting this inflammation promptly is crucial for administering anti-inflammatory drugs, if required. One potential method for detecting inflammation is using molecular imprinted polymers (MIPs). These MIPs, which can be deposited on the CI electrode, provide readout employing impedance measurements, a feature already available on the CI circuit. MIPs designed for this purpose should possess biocompatibility, conductivity, and degradability. The degradability is crucial because there is a limitation on the number of electrodes available, and once the inflammation sensor degrades after the acute inflammation period, it should remain usable as a regular electrode. In this work, conductive poly(3,4-ethylenedioxythiophene) polystyrenesulfonate-based MIPs were synthesized against biotin as a surrogate target marker. Specific biotin binding with MIPs was determined before and after degradation using electrochemical impedance spectroscopy (EIS) and compared with the control nonimprinted polymers (NIPs). Subsequently, MIPs were electrochemically degraded by EIS with different potentials, wherein a potential dependence was observed. With decreasing potential, fewer dissolved polymers and more monomer molecules were detected in the solution in which degradation took place. At a potential of 0.205 V a negligible amount of dissolved polymer in addition to the dissolved monomer molecules was measured, which can be defined as the limiting potential. Below this potential, only dissolved monomer molecules are obtained, which enables renal clearance. Biocompatibility testing revealed that both the polymer and the solution with dissolved monomer molecules do not exceed the ISO 10993-5 cytotoxicity threshold. Based on these findings, we have developed conductive, biocompatible, and controllably degradable MIPs capable of detecting biotin. This research work paves the way for the advancement of CIs, where inflammation can be detected using molecular imprinting technology without compromising the stability and biosafety of the product.

Delamination at heterogeneous material interfaces is one of the most prominent failure modes in active implantable medical devices (AIMDs). A well-known example of an AIMD is the cochlear implant (CI). In mechanical engineering, a multitude of testing procedures are known whose data can be used for detailed modeling with respect to digital twins. Detailed, complex models for digital twins are still lacking in bioengineering since body fluid infiltration occurs both into the polymer substrate and along the metal-polymer interfaces. For a newly developed test for an AIMD or CI composed of silicone rubber and metal wiring or electrodes, a mathematical model of these mechanisms is presented. It provides a better understanding of the failure mechanisms in such devices and their validation against real-life data. The implementation utilizes COMSOL Multiphysics^®, consisting of a volume diffusion part and models for interface diffusion (and delamination). For a set of experimental data, the necessary diffusion coefficient could be derived. A subsequent comparison of experimental and modeling results showed a good qualitative and functional match. The delamination model follows a mechanical approach. The results of the interface diffusion model, which follows a substance transport-based approach, show a very good approximation to the results of previous experiments.

Chemosensor technology for trace gases in the air always aims to identify these compounds and then measure their concentrations. For identification, traceable methods are sparse and relate to large appliances such as mass spectrometers. We present a new method that uses the alternative traceable measurement of the ionization energies of trace gases in a way that can be miniaturized and energetically tuned. We investigate the achievable performance. Since tunable UV sources are not available for photoionization, we take a detour via impact ionization with electrons, which we generate using the photoelectric effect and bring to sharp, defined energies on a nanoscale in the air. Electron impact ionization is thus possible at air pressures of up to 900 hPa. The sensitivity of the process reaches 1 ppm and is equivalent to that of classic PID. With sharpened energy settings, substance identification is currently possible with an accuracy of 30 meV. We can largely explain the experimental observations with the known quantum mechanical models.