Femtosecond laser processing, microstructuring of transparent polymers for Lab-on-Chip applications

近年来，IQ小组成功地使用密集的局部飞秒激光照射来证明材料改性，从而在聚合物基材和薄膜的内部增加局部折射率，并将该技术确立为可重复和可靠的方法。可以演示单模衰减值低于0.5 dB/cm的不同类型的波导。因此，所有以前的文献价值几乎被削弱了一个数量级。新项目的重点是飞秒波导的实际应用和实现新的复杂波导结构的考虑下，全3D能力的过程。传播散射损失将进一步减少写入过程中的光束位置稳定，和软件控制的焦点整形是通过使用一个横向相位调制器（SLM）的写入光束实现。这使得同时飞秒激光写入与几个相邻的和相互关联的焦点。通过在写入过程中改变SLM处的相位掩模，可以一次性实现复杂的2D和3D耦合器结构。基于加工过的聚合物薄膜的“移动的实验室”的第一步就是这样的结果，该薄膜透明地放置在智能手机/平板电脑的显示屏上。在胶片中运行的波导网络以多种颜色从显示器单独馈送，并将光传输到前置摄像头，在那里它被灵敏地检测和颜色解析。通过这种方式，可以灵活地读取分布在薄膜上的传感器。最后，中空毛细管可以用相同的飞秒激光写入设置写入聚合物基底中作为微流体通道。与光波导相结合，在一个生产步骤中创建了一个单独的集成芯片实验室。

In recent years, the IQ group has succeeded in using intensive localized femtosecond laser irradiation to demonstrate material modifications and thereby local refractive index increases in the interior of polymer substrates and films and to establish this technique as a reproducible and reliable method. Waveguides of different types with single mode attenuation values below 0.5 dB/cm could be demonstrated. Thus, all previous literature values have been undercut by almost one order of magnitude. The new project focuses on the practical use of femtosecond waveguides and the realization of novel complex waveguide structures under consideration of the full 3D capability of the process. The propagation scattering losses are to be further reduced by beam position stabilization during writing, and software-controlled focus shaping is to be realized by using a transverse phase modulator (SLM) in the writing beam. This enables simultaneous femtosecond laser writing with several adjacent and interrelated foci. By changing the phase mask at the SLM during the writing process, complex 2D and 3D coupler structures can be realized in one go. The first steps towards a 'mobile lab' based on a processed polymer film, which is transparently placed over the display of a smartphone/tablet, are the result. A network of waveguides running in the film is fed individually in multiple colors from the display and transports the light to the front camera, where it is detected sensitively and color resolved. In this way, sensors distributed over the film can be read flexibly. Finally, hollow capillaries can be written in polymer substrates as microfluidic channels with the same femtosecond laser writing setup. Combined with the optical waveguides, an individual integrated lab-on-a-chip is created in a single production step.