Schumayer Sven, Simon Nicolai, Sittkus Benjamin, Wagner Sandra, Bucher Volker, Strasser Torsten
Institute of Microsystems Technology, Furtwangen University, Furtwangen, Germany.
Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany.
Front Med Technol. 2022 Jun 10;4:920384. doi: 10.3389/fmedt.2022.920384. eCollection 2022.
Presbyopia describes the eye's physiological loss of the ability to see close objects clearly. The adaptation to different viewing distances, termed accommodation, is achieved by a change in the curvature of the eye lens induced by the ciliary muscle. A possible approach to correct presbyopia could be to detect the ciliary muscle's neuromuscular signals during accommodation and transfer these signals electronically to a biomimetic, micro-optical system to provide the necessary refractive power. As a preliminary step toward such a described system, a novel three-dimensional and biocompatible lift-off method was developed. In addition, the influence of the distance between the electrically conducting surfaces of the lens on the accommodated signal amplitudes was investigated. Compared to the conventional masking methods, this process has the advantage that three-dimensional surfaces can be masked with biocompatible gelling sugar by utilizing a direct writing process with a dispensing robot. Since gelling sugar can be used at room temperature and is water-soluble, the process presented is suitable for materials that should not be exposed to organic solvents or excessively high temperatures. Apart from investigating the shrinkage behavior of the gelling sugar during the physical vapor deposition (PVD) coating process, this paper also describes the approaches used to partially coat a commercial scleral contact lens with an electrically conductive material. It was shown that gelling sugar withstands the conditions during the PVD processes and a successful lift-off was performed. To investigate the influence of the spacing between the electrically conductive regions of the contact lens on the measured signals, three simplified electrode configurations with different distances were fabricated using a 3D printer. By testing these in an experimental setup, it could be demonstrated that the distance between the conductive surfaces has a significant influence on the amplitude. Regarding the described lift-off process using gelling sugar, it was found that the dispensing flow rate has a direct influence on the line uniformity. Future work should address the influence of the viscosity of the gelling sugar as well as the diameter of the cannula. It is assumed that they are the prevailing limitations for the lateral resolution.
老花眼是指眼睛在生理上失去清晰看到近处物体的能力。眼睛适应不同观看距离的过程，即调节，是通过睫状肌引起晶状体曲率变化来实现的。一种矫正老花眼的可能方法是在调节过程中检测睫状肌的神经肌肉信号，并将这些信号以电子方式传输到仿生微光学系统，以提供所需的屈光力。作为迈向这种所述系统的初步步骤，开发了一种新颖的三维且生物相容的剥离方法。此外，还研究了晶状体导电表面之间的距离对调节信号幅度的影响。与传统的掩膜方法相比，该工艺的优势在于可以通过使用点胶机器人的直接写入工艺，用生物相容的胶凝糖对三维表面进行掩膜。由于胶凝糖可在室温下使用且可溶于水，所以所介绍的工艺适用于不应暴露于有机溶剂或过高温度的材料。除了研究胶凝糖在物理气相沉积（PVD）镀膜过程中的收缩行为外，本文还描述了用导电材料对商用巩膜接触镜进行部分镀膜的方法。结果表明，胶凝糖能够承受PVD过程中的条件，并成功实现了剥离。为了研究隐形眼镜导电区域之间的间距对测量信号的影响，使用3D打印机制作了三种具有不同距离的简化电极配置。通过在实验装置中对这些配置进行测试，可以证明导电表面之间的距离对幅度有显著影响。关于使用胶凝糖的所述剥离过程，发现点胶流速对线均匀性有直接影响。未来的工作应解决胶凝糖的粘度以及插管直径的影响。据推测，它们是横向分辨率的主要限制因素。
