Active deformable, fluid actuated, compliant mechanism for gentle implants and instruments

Prof. L. Zentner
Dr. S. Griebel

The increasing complexity of minimally invasive surgical approaches to various organs and the importance of non-linear access paths demand alternative solutions to conventional medical instruments. These instruments have a complex design, often requiring a larger space, or require extensive components, which harden the whole structure. The resulting high stiffness of these instruments is counter to the intended use. These problems are especially serious for cochlear implants (CI). CI electrodes are inserted into a hollow organ (cochlea) possessing a spiral shape; they stimulate the functionally intact hearing nerve electrically. In patients with residual hearing, the preservation of the remnants of natural hearing is a huge concern. By preserving the intracochlear anatomical substructures using a shallow insertion process, residual hearing can be saved. Despite constant improvement of surgical technology and implants, injuries of the sensitive, functional structures of the inner ear do, unfortunately, occasionally occur during electrode insertion into the cochlea. As a result, the patients suffer a relevant hearing loss (20-30 dB) or become totally deaf during the procedure, so that the combined patient care sought (a CI electrode for lost frequencies and ‘normal’ hearing with still-available hearing) is no longer possible. Our aim is to develop new actuated mechanisms for positioning an implant or a soft instrument into a curved preformed space in the body, such as a cochlea. A basic principle is using the especially compliant mechanisms whereas its deformation is manipulated by changing the inner pressure. High-accuracy navigation in which robot-based technologies are employed during a surgical procedure made it possible to successfully use complicated insertion pathways. The aim is to insert the CI during the operation in the optimal manner coinciding very closely to the natural form of the inner ear, in order to minimize the contact areas between the CI and the surrounding anatomy. An exact mathematical description of the CI deformation is needed if the advantages of compliant mechanisms are to be exploited: defined behaviour with the final position near the modiolus. Such technology would constitute a basic innovation in cochlear implantation, because in all conventional implants either the final position is close to the modiolus or a final position near the modiolus is not sought. Currently, exact insertion involving adaptation to the spiral course of the cochlea during surgery is not, in principle, possible. By means of model-based investigations and simulations, the necessary mechanical qualities of the CI and actuator supported can be developed. The high-precision technology of grinding gives information about the design of the delicate anatomy of the inner ear. With the aid of patterns, it should be possible to demonstrate the functional ability and suitability of the new actuated electrode. These theoretical bases can be used for fluid-actuated endoscopes and catheters for other surgical uses requiring great care.

[*1] - Rau, T. S., Leinung, M., Kardas, D., Müller, C., Rust, W., Fabian, T., Polley, A., and Majdani, O.:
Simulation als Basis optimierter Cochlear Implant-Operationen. In Proc. 25. ANSYS Conference & CADFEM Users Meeting, November 21–23, Congress Center Dresden, 2007
[*2] - Zentner, L.: Mathematical Synthesys of Compliant Mechanism as Cochlear Implant. In Ananthasurech, G. K. et al (Hrsg.):
Micromechanics and Microactuators. Springer Science+Business Media, 2012

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• Zentner, L.: Nachgiebige Mechanismen. München: De Gruyter Oldenbourg, 2014 – ISBN: 978-3-486-76881-7
• Issa, M.; Hügl, S.; Rau, T. S.; Majdani, O.; Zentner, L.: Specific curvature behavior of compliant mechanism with hydraulic activation used for medical instruments or implants. In: Shaping the future by engineering: 58th IWK, 8 - 12 September 2014; Proceedings. Ilmenau: Univ.-Bibliothek, ilmedia, 2014, URN: urn:nbn:de:gbv:ilm1-2014iwk-129:3
• Zentner, L.; Issa, M.; Griebel, S.; Wystup, C.; Hügl, S.; Rau, T. S.; Majdani, O.: Nachgiebiger fluidisch aktuierter Elektrodenträger für Cochlea-Implantate. In: Tagungsband First IFToMM D-A-CH Conference 2015, 11. März 2015, Dortmund. Universität Duisburg-Essen, 2015, URN: urn:nbn:de:hbz:464-20150327-083215-4
• Zentner, L.; Issa, M.; Hügl, S.; Griebel, S.; Rau, T. S.; Majdan, O.: Compliant mechanism with hydraulic activation used for implants and medical instruments. In: International Conference on Systems, Automatic Control and Measurements (SAUM); Niš, 2014.11.12-14, URN: urn:nbn:de:gbv:ilm1-2015200105
• Hügl, S.; Griebel, S.; Zentner, L.; Rau, T. S.; Lenarz, T.; Majdani, O.: Simulation medizinischer Implantate - Analyse fluidisch aktuierter Cochlea-Implantat-Elektrodenträger. In: Conference proceedings : Ansys Conference & 33. CADFEM users' meeting, 24. - 26. Juni 2015, Bremen // Die Fachkonferenz zur Numerischen Simulation. - Grafing bei München: CADFEM GmbH. - 2015, insges. 7 S.
• Hügl, S.; Griebel, S.; Issa, M.; Wystup, C.; Zentner, L. ; Lenarz, T. ; Majdani, O.; Rau, T. S.: Simulation used for feasibility study of fluid-actuated cochlear implant electrodes. In: Biomedizinische Technik. - Berlin [u.a.] : de Gruyter, ISSN 1862278X, Bd. 60 (2015), 1, S. 318, http://dx.doi.org/10.1515/bmt-2015-5013
• Hügl, S.; Weiss, C.; Rau, T. S.; Lenarz, T.; Majdani, O.: Automatisierung der Schliffpräparation zur dreidimensionalen Rekonstruktion histologischer Proben. - In: GMS current posters in otorhinolaryngology, head and neck surgery. - Düsseldorf : gms, ISSN 18651038, Bd. 11 (2015), insges. 1S., http://dx.doi.org/10.3205/cpo001222
• Hügl, S.; Rau, T. S.; Griebel, S.; Wystup, C.; Zentner, L.; Lenarz, T.; Majdani, O.: Fluidisch aktuierte Cochlear-Implant Elektrode. - In: 87. Jahresversammlung der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie e.V. / Jahresversammlung der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie e.V. ; 87 (Düsseldorf) : 2016.05.04-07. - Düsseldorf : German Medical Science GMS Publishing House, (2016), insges. 1S. http://dx.doi.org/10.3205/16hnod336
• Hügl,S.; Rau, T. S.; Griebel S. ; Zentner,L.; Lenarz, T.; Majdani , O.: Sensitivity analysis on cochlear implants with fluidactuation. In: Biomedizinische Technik. - Berlin [u.a.] : de Gruyter, ISSN 1862278X, Bd. 61 (2016), S1, Seite S. 228, http://doi.org/10.1515/bmt-2016-5018
• Hügl, S.; Griebel, S.; Zentner, L.; Lenarz, T.; Majdani, O.; Rau, T. S.: Analysis of Fluid Actuated Cochlear Implant Electrode-Carrier. In: Computer Aided Medical Engineering. Expert Verlag. 06/2016 ISSN:2190-0698
• Hügl, S.; Eckardt, F.; Lexow, G.J.; Majdani, O.; Lenarz, T.; Rau, T.S.: Increasing the resolution of morphological 3D image data sets through image stitching: application to the temporal bone. - In: Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization. - Taylor & Francis. published online: 16.02.2016. http://dx.doi.org/10.1080/21681163.2015.1137080
• Zentner, L.; Hügl, S.; Wystup, C.; Griebel, S.; Issa, M.; Rau, T; Majdani, O: Nachgiebiger Elektrodenträger für Cochlea-Implantate mit hydraulischer Aktuierung. - In: Forschung im Ingenieurwesen (2016) 80: 57. http://dx.doi.org/10.1007/s10010-016-0202-0
• Zentner, L.; Griebel, S.; Wystup, C.; Hügl, S.; Rau, T.S.; Majdani, O.: Synthesis process of a compliant fluidmechanical actuator for use as an adaptive electrode carrier for cochlear implants. In: Mechanism and Machine Theory, Bd 112 (2017), 155-171. http://dx.doi.org/10.1016/j.mechmachtheory.2017.02.001

• Griebel, S.; Hügl., S.; Rau, T.S.; Majdani, O.; Wystup, C.; Lenarz, T.; Zentner, L.:
  Adaptiver Elektrodenträger, seine Verwendung und Verfahren zu seiner Insertion
  Aktenzeichen: DE 10 2016 003 259.2, Patentanmeldung vom 04.03.2016
   

Gold medal at the international trade fair "Ideas-Inventions-New Products (IENA)" Nuremberg, 2015 Topic: "Adaptive electrode array, its use and method for inserting a cochlear implant electrode array".

TU Ilmenau - Compliant Systems Group (formerly Mechanism Technology Group) - Project coordination -

PD Dr. med. Omid Majdani, Clinic and Polyclinic for Ear, Nose and Throat. Otorhinolaryngology (ENT), Hannover Medical School (MHH)

01/2014 - 07/2017

DFG - Deutsche Forschungsgemeinschaft
DFG - reference number: ZE 714/9-1