Elevating stiffness without compromising compliance and agility is a key problem for soft finger applications, especially for articulate ones. Inspired by human finger, a multijoint soft finger with dual morphing through active/passive variable rigidity is proposed. The fabricated soft finger weighs 27.4 g. Conductive thermoplastic starch polymers (CTPSs) are embedded in a U-shape-joint pneumatic soft actuator segmentally like biological phalanges. Their stiffness can be independently adjusted utilizing customized thermomechanical property. Yoshimura origami imitating ligaments can passively match deformation and stiffness of the joints. Through electrothemal activation of CTPSs, the finger can realize dual independent articulate morphing: stiffened phalanges (mode 1) for dexterous manipulation and heavy load, softened phalanges (mode 2) for large deformation contact and light load. Comparative experiments of bending angle, output force, and stiffness are carried out between the active and passive stiffness adjustment of mode 1 and mode 2. The results show that the output force and stiffness of the finger adopting mode 1 can be improved more than two times and five times, and its compliance using mode 2 is almost similar, compared with the pure soft one. To further demonstrate performances of dual-mode morphing, a three-fingered gripper is assembled for grasping and manipulating targets with different shapes, sizes, rigidity, and weight, including playing card, unshelled raw egg, grapes, and unscrewing the bottle cap. It can successfully lift a dumbbell weighing 1460 g with a 7.6 load/weight ratio through a two-mode switch.

中文翻译：

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一种受人启发的具有可变刚度机制的双模式变形的软手指

在不影响柔顺性和灵活性的情况下提高刚度是软手指应用的一个关键问题，尤其是对于有关节的手指。受人类手指的启发，提出了一种通过主动/被动可变刚度实现双变形的多关节软手指。制造的软手指重 27.4 克。导电热塑性淀粉聚合物 (CTPS) 像生物指骨一样分段嵌入 U 形关节气动软执行器中。它们的刚度可以利用定制的热机械特性独立调整。吉村折纸模仿韧带可以被动匹配关节的变形和刚度。通过CTPSs的电热激活，手指可以实现双独立关节变形：用于灵巧操作和重载的僵硬指骨（模式1），用于大变形接触和轻载荷的软化指骨（模式 2）。对方式一和方式二的主动和被动刚度调节进行了弯曲角度、输出力和刚度对比实验，结果表明采用方式一的手指的输出力和刚度可以提高两倍以上和 5 倍，其使用模式 2 的顺应性与纯软模式相比几乎相似。为了进一步展示双模变形的性能，组装了一个三指夹持器，用于抓取和操纵不同形状、大小、刚度和重量的目标，包括扑克牌、带壳生鸡蛋、葡萄和拧开瓶盖。它可以通过双模式开关以7.6的负载重量比成功举起一个重达1460克的哑铃。