Yu Yunru, Guo Jiahui, Sun Lingyu, Zhang Xiaoxuan, Zhao Yuanjin
State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China.
Research (Wash D C). 2019 Jun 19;2019:6906275. doi: 10.34133/2019/6906275. eCollection 2019.
Inspired by helical or spiral veins, which endow plants with excellent flexibility and elasticity to withstand storms, we present novel hollow microsprings with ionic liquid encapsulation for flexible and stretchable electronics. The microsprings were generated by using a coaxial capillary microfluidic device to consecutively spin poly(vinylidene fluoride) (PVDF) presolution and an ionic liquid, which formed laminar flows in the coaxial injection microfluidic channels. The fast phase inversion of PVDF helps to form the core-shell structure of a microfiber and guarantees the in situ encapsulation of ionic liquid. The hybrid microfiber can then spiral and be further solidified to maintain the helical structure with increasing flow rates of the injection fluids. Because of the feasible and precise control of the injection fluids during the microfluidic spinning, the resultant microsprings have controlled core-shell structures, helical pitches, and corresponding electromechanical properties. By further embedding them into stretchable films, the simple paradigm of a flexible device shows great conductive performance in tensile tests and even motion cycles, which could be explored as a promising candidate in stretchable sensors, flexible electronics, and electronic skins.
受赋予植物出色柔韧性和弹性以抵御风暴的螺旋状或螺旋形叶脉的启发，我们展示了一种用于柔性可拉伸电子产品的、封装有离子液体的新型中空微弹簧。这些微弹簧是通过使用同轴毛细管微流控装置连续纺丝聚偏二氟乙烯（PVDF）预溶液和离子液体而生成的，它们在同轴注入微流控通道中形成层流。PVDF的快速相转化有助于形成微纤维的核壳结构，并确保离子液体的原位封装。然后，混合微纤维可以螺旋化并进一步固化，以随着注入流体流速的增加而保持螺旋结构。由于在微流控纺丝过程中对注入流体进行了可行且精确的控制，所得微弹簧具有可控的核壳结构、螺旋节距以及相应的机电性能。通过将它们进一步嵌入可拉伸薄膜中，这种柔性器件的简单范例在拉伸测试甚至运动循环中都表现出出色的导电性能，有望成为可拉伸传感器、柔性电子产品和电子皮肤中的有前途的候选材料。
