Abstract
Externally attached stiffeners/actuators are required for providing structural rigidity to flexible parylene-based cochlear implants for maintaining a perimodiolar shape in the post-implantation phase. Such backing devices being bulky add dead volume to the implant making the fluid-filled scala tympani chamber more congested during insertion resulting in shallow insertion depth. A thin film parylene array with integrated stiffener will provide a smaller implant cross-section potentially allowing a deeper implantation. A novel fabrication method for embedded cochlear implant stiffener structures by hot embossing of poly(lactic acid) (PLA) films is reported. PLA packaging film has been hot embossed on parylene coated silicon substrates using a custom fixture. Embossing results show good pattern transfer fidelity. Rigidity of the embossed stiffeners has been compared with the structural rigidity of poly (ethylene terephthalate) actuators.
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Acknowledgments
The authors are grateful to Angelique Johnson of University of Michigan for providing parylene array layout designs and related dimensions. We also extend our sincere thanks to Chuck Markley of Plastic Suppliers, Inc. for generously donating EarthFirst® PLA packaging sheets. This work was supported by the Engineering Research Center Program of the National Science Foundation under award number EEC-9986866.
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Tewari, R., Friedrich, C. Hot embossing of poly(lactic acid) films for an embedded cochlear implant stiffener. Microsyst Technol 16, 1601–1607 (2010). https://doi.org/10.1007/s00542-010-1084-y
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DOI: https://doi.org/10.1007/s00542-010-1084-y