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中国物理学会期刊

软物质激光微纳加工技术

CSTR: 32037.14.aps.71.20220625

Laser micro/nanomachining technology for soft matter

CSTR: 32037.14.aps.71.20220625
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  • 针对软物质的激光微纳加工技术, 通过激光辅助机械注射和可控自组装来实现装配软物质微滴球体结构的目的, 相较于传统的液滴微流控技术具有显著的优势. 本文研究了激光能量、光束尺寸、曝光位置等激光参数对激光辅助机械注射的影响, 得到了最佳的激光参数条件范围, 发现过高的激光强度(如0.365 mW)可诱发液晶材料的对流而不注入子液滴. 研究了表面活性剂浓度、液晶种类和相态等材料因素对注射机械力, 以及注入子液滴尺寸的影响. 证实表面活性剂浓度影响的实质是不同的离子浓度会改变相同升温条件下所形成的界面张力梯度值(注射机械力提高3.1倍); 发现液晶的相态对激光注射没有影响, 而液晶的种类会改变注入难度(弹性常数K值越高越难注入). 此外, 引入液晶微滴的拓扑相错线作为子液滴的自组装模板, 分析了注入子液滴在拓扑相错线上的自组装动力学过程. 软物质激光微纳加工技术可应用于光电子、生物医药等领域的三维球体结构的极端加工与应用开发.

     

    Laser micro/nanomachining technology for soft matter achieves the purpose of fabricating the spherical structures of soft matter by combing laser-assisted mechanical injection and controllable self-assembly, which has significant advantages in comparison with conventional methods like droplet microfluidics. In this study, the effects of laser parameters such as laser energy, beam size, and irradiation position on the injection are investigated. It is found that there also exists one upper limit of the laser energy, and if the laser irradiation is too strong, it can introduce a convection flow of liquid crystal rather than trigger off the injection of guest microdroplets. Thus, the laser injection can be achieved in a specific energy range of the laser irradiation. By manipulating the laser beam with a smaller size, the guest water microdroplets can be injected at the preselected location on the surface of a host liquid crystal droplet. In addition, the influences of material parameters such as the surfactant concentration, the material type and phase state of liquid crystal on the laser-assisted mechanical injection, and the size of the injected guest droplet are investigated. It is found that the liquid crystal droplet with higher surfactant concentration requires less energy from the laser irradiation to generate enough mechanical force to trigger off the injection. Because under the same temperature increment, the liquid crystal droplet with higher ion concentration enjoys a stronger surface tension gradient. By comparing several different types of liquid crystals, it is found the injection of guest droplets into a host with a higher elastic constant liquid crystal can be more difficult. The influences of the material type of liquid crystal and the concentration of surfactant on the critical size of guest microdroplets are summarized. Finally, the defect lines of liquid crystal are introduced as the self-assembly template, through which microdroplets of liquid crystal with the sophisticated spherical structure are fabricated. The self-assembly kinetic behaviors of guest droplets in the defect line are analyzed. The laser micro/nanomachining technology of soft matter can be applied to the extreme processing and application development of 3D spherical structures in the fields of optoelectronics, photonics, and biomedicine.

     

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