Modification of the surface of stimulating electrodes by electrospinning

人工耳蜗（CI）用于治疗耳聋和重度听力损失。作为植入的自然反应，结缔组织在植入后不久形成，围绕并绝缘整个植入体。这种组织形成导致不可预测的刺激传播和能量消耗增加。在耳聋过程中，受电刺激的听觉神经细胞（螺旋神经节神经元，SGN）也会死亡。以往的尝试，旨在提高CI电极集成度，从事沿电极阵列的一般应用。根据目前的知识状况，在局部接触领域的应用将是比较有前途的方法。本项目旨在通过将上述方法与基于纤维的加工方法静电纺丝相结合，对表面进行局部改性。定制的基于纤维的表面特性操作旨在(i)在不显著影响电学特性的情况下减少结缔组织细胞的粘附，（ii）使物质从触点表面释放（抗炎，神经营养）。在项目过程中，医疗级硅弹性体将通过静电纺丝加工并沉积在试件和植入物上。接下来将描述纤维结构对电极触点电性能的影响。阻抗的电位增加不应超过5欧姆的阈值。为了实现这一目标，产生了不同的纤维直径和纤维垫厚度并进行了表征。其他的技术将被开发，以饱和疏水硅纤维结构与淋巴管。因此，旨在利用纤维垫的间隙作为电极应用物质的储存库。在使用测试标本成功进行体外释放和生物相容性研究后，这些方法被转移到真正的电极载体（植入物）上。除了开发合适的制造策略外，还将研究纤维垫在插入耳蜗时的分层稳定性。项目完成后，将获得广泛的知识和技术，这将允许(i)使用纤维构建电极表面；（ii）单个纤维的功能化以及含有活性剂的纤维结构；（iii）调查上述措施对电极性能和生物相容性的影响。

Cochlear implants (CI) are used to treat deafness and profound hearing loss. As a natural reaction to implantation, connective tissue forms shortly after implant insertion, surrounding and therefore electrically insulating the entire implant. This tissue formation leads to unpredictable stimulus propagation and increased energy consumption. In the course of deafness, auditory nerve cells (spiral ganglion neurons, SGN), targeted by electrical stimulation, also die. Previous attempts, aiming at the improvement of CI electrode integration, engaged in a general application along the electrode array. According to the current state of knowledge, a local application in the area of the contacts would be more promising approach.The present project aims at the local modification of the surface by merging the aforementioned approaches with the fiber-based processing method electrospinning. Tailor-made fiber-based manipulation of the surface properties is intended to (i) reduce the adhesion of connective tissue cells without significantly affecting the electrical properties and (ii) enable substance release (anti-inflammatory, neurotrophic) from the surfaces of the contacts. In the course of the project, medical grade silicone elastomers will be processed by electrospinning and deposited on test specimens and implants. This will be followed by a characterization of the influence of the fiber structures on the electrical properties of the electrode contacts. Potential increases in impedance should not exceed a threshold of 5 kOhm. To achieve this goal, different fiber diameters and fiber mat thicknesses are generated and characterized. Additional techniques will be developed to saturate the hydrophobic silicone fiber structures with perilymph. Therefore, aiming to utilize the interstices of the fiber mats as a reservoir for the substances to be applied by the electrode. Following successful in vitro studies on release and biocompatibility using test specimens, the methods are transferred to real electrodes carriers (implants). In addition to the development of suitable manufacturing strategies, the delamination stability of the fiber mats during insertion into the cochlea will be investigated. After completion of the project, extensive knowledge and techniques will be available, which will allow (i) structuring of electrode surfaces by using fibers (ii) functionalization of single fibers as well as the fiber construct with active agents and (iii) investigation of the influence of the mentioned measures on the electrical electrode properties as well as biocompatibility.