Inherent silicone based sensor elements for actively deformable, fluidically actuated medical devices

• Applicant: Professorin Dr.-Ing. Lena Zentner
• Subject Area: Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics ; Microsystems
• Term: from 2013 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 241357279

The aim of the project is the basic investigation of compliant sensor elements made of conductive silicone with regard to medical instrumentation. The basis for this is the preliminary work on the integration of a compliant actor system into the medical instruments using the example of an electrode carrier (EC) for cochlear implants (CI). As a logically consistent amendment, within this follow-up project the feedback about deformation states and / or interaction forces with the surrounding tissue during insertion of the instruments is to be followed by an inherent, likewise compliant sensor technology (by means of material and functional coherence).In order to obtain the advantages of compliant instrumentation despite the integration of sensors, only compliant sensor elements made of conductive silicone are used. This material is just as flexible as the basic material of the instruments and the already developed actuator system. Additionally, the material is electrically conductive so that it changes its electrical resistance as a function of the material elongation.Within the follow-up project, the possibilities and limitations of compliant sensor technology shall be investigated. The focus are the identification of relevant design parameters, which must be taken into account in the design process of sensory areas, as well as the development of an analytical-model-based synthesis method for inherent sensor technology. This also includes the establishment of necessary methods for shaping, structuring and contacting the sensor elements. Due to the scaling of the instrumentation, embodied as a compliant rod-shaped fluid-mechanical actuator (FMA), within the framework of modeling, differently sized instruments are considered. This is intended to exploit the limits of miniaturization. As an example of a FMA with sensors, the electrode carrier of a CI system is chosen because of the particularly demanding requirements for miniaturization and the careful procedure of insertion. In order to develop the interactions and laws of contact forces between the implant and the surrounding tissue, as well as the internal deformations that can be detected by the sensor system, the numerical models of the electrode carrier are verified with the experimental investigations and further developed in an iterative process. For the necessary, realistic models, physiological characteristics of the cochlea are determined experimentally and the morphological diversity of the human cochlea is to be categorized.Finally, the work results in a functional demonstrator setup of an CI electrode carrier with inherent sensor technology and which can be actuated. Afterwards, the fundamentals developed in the project will also form a basis for sensorized, fluidically actuated compliant endoscopes and catheters and thus for further surgical applications.

• DFG Programme: Research Grants