A polymer based horizontal single step waveguide for the sensing of alcohol is developed and analyzed. The waveguide is fabricated by 3-dimensional (3D) printing digital light processing (DLP) technology using monocure 3D rapid ultraviolet (UV) clear resin with a refractive index of n = 1.50. The fabricated waveguide is a one-piece tower shaped ridge structure. It is designed to achieve the maximum light confinement at the core by reducing the effective refractive index around the cladding region. With the surface roughness generated from the 3D printing DLP technology, various waveguides with different gap sizes are printed. Comparison is done for the different gap waveguides to achieve the minimum feature gap size utilizing the light re-coupling principle and polymer swelling effect. This effect occurs due to the polymer-alcohol interaction that results in the diffusion of alcohol molecules inside the core of the waveguide, thus changing the waveguide from the leaky type (without alcohol) to the guided type (with alcohol). Using this principle, the analysis of alcohol concentration performing as a larger increase in the transmitted light intensity can be measured. In this work, the sensitivity of the system is also compared and analyzed for different waveguide gap sizes with different concentrations of isopropanol alcohol (IPA). A waveguide gap size of 300 µm gives the highest increase in the transmitted optical power of 65% when tested with 10 µL (500 ppm) concentration of IPA. Compared with all other gaps, it also displays faster response time (t = 5 seconds) for the optical power to change right after depositing IPA in the chamber. The measured limit of detection (LOD) achieved for 300 µm is 0.366 µL. In addition, the fabricated waveguide gap of 300 µm successfully demonstrates the sensing limit of IPA concentration below 400 ppm which is considered as an exposure limit by “National Institute for Occupational Safety and Health”. All the mechanical mount and the alignments are done by 3D printing fused deposition method (FDM).

开发并分析了一种用于酒精传感的基于聚合物的水平单步波导。通过使用折射率为n的单固化3D快速紫外线（UV）透明树脂，通过3维（3D）打印数字光处理（DLP）技术制造波导。= 1.50。所制造的波导是一件式的塔形脊结构。它旨在通过降低包层周围的有效折射率来实现最大的光限制在纤芯处。利用3D打印DLP技术产生的表面粗糙度，可以打印出具有不同间隙尺寸的各种波导。利用光重新耦合原理和聚合物溶胀效应，对不同的间隙波导进行了比较，以实现最小的特征间隙尺寸。由于聚合物与醇的相互作用会导致这种效应，而这种相互作用会导致醇分子在波导芯内扩散，从而将波导从泄漏型（无酒精）更改为引导型（有酒精）。利用这个原理，可以测量在透射光强度增加较大时执行的酒精浓度分析。在这项工作中，还针对具有不同浓度的异丙醇（IPA）的不同波导间隙尺寸，对系统的灵敏度进行了比较和分析。当使用10 µL（500 ppm）浓度的IPA进行测试时，波导间隙尺寸为300 µm可使传输光功率最大增加65％。与所有其他差距相比，它还显示了更快的响应时间（当使用10 µL（500 ppm）浓度的IPA进行测试时，波导间隙尺寸为300 µm可使传输光功率最大增加65％。与所有其他差距相比，它还显示了更快的响应时间（当使用10 µL（500 ppm）浓度的IPA进行测试时，波导间隙尺寸为300 µm可使传输光功率最大增加65％。与所有其他差距相比，它还显示了更快的响应时间（t = 5秒），以便在将IPA放入腔室内后立即改变光功率。300 µm的测量检出限（LOD）为0.366 µL。此外，制造的300 µm波导间隙成功地证明了IPA浓度的感测极限低于400 ppm，被“国家职业安全与健康研究所”视为暴露极限。所有机械安装和对准均通过3D打印熔融沉积方法（FDM）完成。