A Nature-Inspired, Flexible Substrate Strategy for Future Wearable Electronics
A Nature-Inspired, Flexible Substrate Strategy for Future Wearable Electronics
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DOI：
10.1002/smll.201902440
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发表时间：
2019-08-01
期刊：
影响因子：
13.3
通讯作者：
Liu, Xuqing
中科院分区：
文献类型：
--
作者：
Zhu, Chuang;Chalmers, Evelyn;Liu, Xuqing
灵活性在可穿戴电子产品中起着至关重要的作用。反复弯曲经常导致导电性的急剧下降，因为在金属涂层中形成许多微裂纹，这对于柔性导体是不期望的。在此，导电织物为基础的触觉传感器和金属涂覆的聚氨酯海绵为基础的弯曲传感器具有优越的上级灵活性，用于监测人体触摸和手臂运动，分别提出。单宁酸是一种传统的媒染剂，被引入到各种柔性基底上，为催化剂吸附和随后的无电沉积（ELD）提供了一个完美的平台。通过了解化学镀金属沉积物的成核、生长和结构，可以通过简单地改变镀覆时间在纳米尺度上控制金属纳米颗粒的表面形态。当化学镀时间为20 min时，制得的导电纤维的归一化电阻（R/R-0）仅为1.6，远低于相同条件下60 min电沉积样品（R/R-0接近5）。这是因为纳米颗粒之间的大量未填充间隙防止金属膜在弯曲下破裂。重要的是，开尔文问题与沉积的导电涂层有关，因为金属电池具有蜂窝状结构，这是解释导电性和柔性关系的基本原理。
Flexibility plays a vital role in wearable electronics. Repeated bending often leads to the dramatic decrease of conductivity because of the numerous microcracks formed in the metal coating layer, which is undesirable for flexible conductors. Herein, conductive textile-based tactile sensors and metal-coated polyurethane sponge-based bending sensors with superior flexibility for monitoring human touch and arm motions are proposed, respectively. Tannic acid, a traditional mordant, is introduced to attach to various flexible substrates, providing a perfect platform for catalyst absorbing and subsequent electroless deposition (ELD). By understanding the nucleation, growth, and structure of electroless metal deposits, the surface morphology of metal nanoparticles can be controlled in nanoscale with simple variation of the plating time. When the electroless plating time is 20 min, the normalized resistance (R/R-0) of as-made conductive fibers is only 1.6, which is much lower than a 60 min ELD sample at the same conditions (R/R-0 approximate to 5). This is because a large number of unfilled gaps between nanoparticles prevent metal films from cracking under bending. Importantly, the Kelvin problem is relevant to deposited conductive coatings because metallic cells have a honeycomb-like structure, which is a rationale to explain the relationships of conductivity and flexibility.