在不同基材上制备液态金属-高分子复合物导体的初步研究

FABRICATION OF LIQUID-METAL-POLYMER CONDUCTORS ON DIFFERENT SUBSTRATES

钟乐霓

11849027

硕士

生物医学工程

蒋兴宇

2020-06-04

2020-07-08

哈尔滨工业大学

深圳

可穿戴设备的发展不断推动着柔性电子工艺的进步。在柔性电子工艺中, 印刷电子学是实现其工业化生产的关键, 而这其中导电油墨的制备和印刷工艺设备决定了柔性电子最终的性能。传统印刷导电油墨分为碳系导电油墨、有机高分子导电油墨和金属导电油墨。金属导体油墨制备柔性电子往往需要刻蚀或高温烧结等步骤, 制备工艺复杂。高分子导电油墨制备工艺相对简单, 可印刷性更好, 但是所制备器件的电气性能较差。而液态金属拥有良好的电导性与可加工性, 结合了二者的优点, 因此被越来越多地应用到柔性电子领域。常用的液态金属是镓基合金, 但是其表面张力大, 对材料浸润能力差, 往往需要进行油墨化处理来提高其可印刷性。油墨化的液态金属和高分子材料结合制备金属-高分子复合物导体 (Metal-polymer conductor, MPC), 以此实现柔性可穿戴设备。本课题对平面型基材和纤维型基材分别建立了两种MPC体系, 通过考察两种MPC体系的工艺参数, 分别提出了平面型MPC和纤维型MPC的一个可穿戴应用设计。在不同基材上制备MPC的过程中, 我们分别选用了2种油墨化方法 (制备液态金属微粒悬浮液和氧化法), 以及2种加工工艺 (丝网印刷和浸涂法), 分别探究了油墨制备和印刷基底材料对MPC电气性能的影响, 并通过扫描电子显微镜成像、阻值测量、接触角测量、应力应变等方法进行表征。制备平面型MPC, 我们选择聚吡咯烷酮 (Polyvinyl pyrrolidone, PVP) 溶液作为镓铟合金 (Eutectic Gallium-Indium, EGaIn) 的分散剂, 通过超声处理制备EGaIn-PVP油墨。丝网印刷EGaIn-PVP油墨使其图案化, 干燥处理后, 通过机械应力“烧结”油墨获得MPC。结果显示, 2.67 g/ml 的EGaIn在5 wt% PVP溶液中超声90 s时, 所制备的油墨有较好均一性和稳定性, 且印刷所得MPC有更好的电学表现。该条件下, EGaIn-PVP油墨颗粒平均粒径为0.78 μm, 在聚氨酯柔性基底上能实现很好的印刷效果, 印刷电路精度达到100 μm。我们在表面平整化修饰的聚氨酯纤维表面浸涂一层EGaIn, 并随后封装一层硅胶实现纤维型MPC制备。结果显示, 选用2.8 cm/min的浸涂速度浸涂2次以上能使MPC获得良好的电学性能, 并实现200%的拉伸应变和600次的拉伸循环。针对以上的工艺参数探究, 我们分别设计了基于平面MPC的乳酸燃料电池和基于纤维MPC的发光织物。该电池具有良好的弯折性能和一定的拉伸性能, 在20 mM的乳酸溶液体系下实现了60 mV的电势输出。而该发光织物能够在工作条件下实行一定的弯折和拉伸。本课题最终的目标是通过对这些工艺条件的探索, 能够真正实现这两款可穿戴设备的制备, 并且实现其工业化生产。

The development of wearable devices promotes the progress of flexible electronics. Printed electronics is the key to industrial production of flexible electronics, which is determined by conductive ink, printing process parameters, and equipment. Traditional conductive ink is divided into carbon conductive ink, organic conductive ink, and metal conductive ink. After printing on substrates, metal conductive ink requires etching or sintering, which is with complicated fabrication. The preparation process of polymer conductive ink is relatively simple. However, the electrical performance of the device made by polymer conductors is poor. Combining advantages of metal and polymer, liquid metal has good electrical conductivity and processability, so it is increasingly used in the field of flexible electronics. Eutectic gallium-indium (EGaIn) is the commonly used liquid metal, but with large surface tension and poor wettability to the substrates, often requiring pretreatment to improve its printability. Liquid metal and polymer materials are combined to prepare metal-polymer conductor (MPC) to achieve flexible wearable devices. The dissertation establishes two MPC systems for planar substrates and fiber-based substrates respectively. By examining the fabricating parameters of the two MPC systems, wearable devices for planar MPC and fiber MPC are designed respectively.In fabrication of MPC on different substrates, we selected two methods to prepare EGaIn ink (preparation of liquid metal particle suspension and oxidation method) respectively, and two processing techniques (screen printing and dip coating method) respectively. The dissertation is aiming at determining effects on MPC fabrication, including processing parameters and substrate materials, by scanning electron microscope imaging, resistance measurement, contact angle measurement, stress-strain testing.For the preparation of planar MPC, we mix EGaIn with polyvinyl pyrrolidone (PVP) and sonicate the mixture to get EGaIn-PVP ink. The EGaIn-PVP ink is screen-printed to pattern circuits. After drying printed circuits, MPC is obtained by mechanically sintering the ink without high temperature processing. The results show that when EGaIn at 2.67 g/ml is sonicated in 5 wt% PVP solution for 90 s, the prepared ink has better uniformity and stability, and the printed MPCs have better electrical performance. Under these conditions, the average particle size of EGaIn-PVP ink particles is about 0.78 μm. Also, the accuracy of the printed circuits reaches about 100 μm.We use dip-coating method to coat a layer of EGaIn on the surfaced-smooth-modified polyurethane fiber, and then to encapsulate it by a layer of silicone to fabricate fiber-based MPCs. The results show that using a dip-coating speed of 2.8 cm/min and three times of dip-coating can achieve good electrical properties for MPCs which achieve 200% tensile strain and 600 tensile cycles.In view of the above process parameters, we designed a lactate biofuel cell based on planar MPC and an electroluminescent fabric based on fiber MPC. The battery has good bending performance and certain tensile performance, as well as achieved a potential output of 60 mV in 20 mM lactic acid solution. The light-emitting fabric can be bent and stretched under working conditions. The essential goal of the dissertation is to explore the processing parameters of these two wearable devices. Further, it can be the guideline of their industrial production in the future.

液态金属 金属高分子复合物 制备工艺 丝网印刷 浸涂 可穿戴设备

liquid metal metal-polymer conductor fabrication screen-printing dip-coating wearable device

中文

联合培养

南方科技大学

钟乐霓. 在不同基材上制备液态金属-高分子复合物导体的初步研究[D]. 深圳. 哈尔滨工业大学,2020.