Introduction: What is the Paper About?

• This research is inspired by nature—many animals adapt their shape to survive. Think of lizards shedding their tails or ants linking together to cross gaps.
• Self-amputation (or autotomy) is when an organism deliberately detaches a part of its body to escape danger.
• Interfusion refers to individuals temporarily fusing together, much like ants forming a bridge to overcome obstacles.
• The paper applies these ideas to soft robotics by developing a reversible joint that lets robots “shed” or “fuse” parts as needed.

Materials and Method: How is the Reversible Joint Made?

• The joint is built using a thermoplastic elastomer called SIS, which is softened by mixing with paraffin oil. This makes it flexible and easier to work with.
• A special structure called Bicontinuous Thermoplastic Foam (BTF) is created by infusing the softened SIS into a silicone matrix. This combination allows the material to be both strong and flexible.
• The process is simple: heat the joint above a specific temperature so that the SIS melts into a sticky, viscous liquid. When two heated surfaces meet, the melted SIS fuses them together. Then, as it cools, the connection solidifies.
• Imagine it like melting a piece of cheese between two slices of bread; when it cools, the cheese helps hold the bread together.

Testing and Mechanical Performance

• Tensile tests showed that the joint can withstand a force of around 68.4 kPa at room temperature—meaning it is very strong when needed.
• T-peel tests (a way to measure how much force it takes to peel the joint apart) confirmed that the bond is robust at room temperature but weakens significantly when heated.
• This drop in strength when heated makes it easy to detach the joint when necessary.
• Cyclic tests (repeating the connection and disconnection process) showed that the joint can be reused many times (over 250 cycles are predicted) while still maintaining enough strength for practical use.

Application Demonstrations

• Self-Amputation in a Soft Quadruped Robot:
  • The robot’s limbs are connected to its body with these reversible joints.
  • If a limb gets trapped (for example, under a rock), a built-in copper heater warms the joint.
  • This heating causes the joint to weaken, allowing the robot to “shed” the stuck limb and continue moving on three legs.
• Interfusion in Soft Crawlers:
  • Individual soft crawlers use the reversible joints to connect with each other.
  • When facing a gap that is too wide for one unit to cross alone, several crawlers fuse together, effectively creating a longer, continuous body.
  • After crossing the gap, the joints are heated again to separate the robots so they can continue independently.

Key Insights and Conclusions

• The reversible joint mimics natural adaptations by offering a strong connection when needed and a weak link when detachment is required.
• This design allows soft robots to change their shape dynamically—by “losing” a limb to escape or “joining” together to overcome obstacles.
• It provides a practical approach for developing future modular and adaptive robots that can adjust to unpredictable environments.
• The study emphasizes that combining high strength with easy detachment is key to achieving versatile and resilient robotic systems.

Additional Details from the Experimental Section

• The fabrication process involves plasticizing SIS with paraffin oil, using sugar particles to create a porous (foam-like) structure, and then infusing this with silicone. This ensures the joint is both flexible and strong.
• Mechanical tests such as T-peel and cyclic loading confirmed the joint’s performance, showing it can endure repeated use with only moderate loss in strength.
• Copper heaters are integrated to rapidly heat the joint, making connection and disconnection quick and efficient.
• After heating, the joint cools naturally to room temperature, which causes the melted SIS to solidify and lock the connection in place.

引言：论文主要内容

• 本研究受到自然界的启发——许多动物为了生存，会改变自身的形态，比如蜥蜴主动断尾或蚂蚁联结成桥跨越障碍。
• 自截（或称自割）指的是生物在遭遇危险时，主动断开部分身体以逃生。
• 融合指的是个体之间临时结合，就像蚂蚁合作形成桥梁以克服困难。
• 该论文将这些自然策略应用于软体机器人，开发了一种可逆接头，使机器人可以根据需要“脱离”或“融合”身体部分。

材料与方法：可逆接头的制作

• 接头采用一种名为SIS的热塑性弹性体，通过与石蜡油混合使其变得更柔软、更易于加工。
• 制作过程中构建了一种称为双连续热塑性泡沫（BTF）的结构，将软化后的SIS注入硅胶基体中，形成既强韧又柔软的复合材料。
• 过程非常简单：将接头加热到特定温度，使SIS融化成粘稠的液体；当两个加热后的表面接触时，融化的SIS将它们粘合在一起；随后冷却固化，形成牢固的连接。
• 可以把它想象成把融化的奶酪夹在两片面包中，冷却后奶酪把面包牢牢粘合在一起。

测试与机械性能

• 拉伸测试表明，接头在室温下可承受大约68.4 kPa的应力，显示出很高的强度。
• T形剥离测试用于测量在不同温度下分离接头所需的力，结果显示室温下接头牢固，而加热后强度大幅下降，便于分离。
• 这种在加热时强度迅速下降的特性使得接头在需要时可以轻松断开。
• 循环测试表明，反复连接与断开的过程中，接头能够保持足够的性能，预计可重复使用超过250次。

应用示范

• 软体四足机器人的自截示范：
  • 机器人利用可逆接头将四肢与躯干连接起来。
  • 当某个肢体被卡住（例如被岩石压住）时，内置的铜加热器会加热该接头。
  • 加热使接头弱化，从而使机器人能够“脱离”被困的肢体，继续以三足行走。
• 软体爬行机器人融合示范：
  • 单个软体爬行机器人通过可逆接头相互连接。
  • 当遇到单个机器人无法跨越的宽缝隙时，多台机器人融合在一起，形成一个更长的整体。
  • 跨越障碍后，再次加热接头使机器人分离，各自独立行动。

关键见解与结论

• 可逆接头模仿了自然界中动物自截与融合的动态形态变化，既能在需要时提供高强度，又能在加热后迅速断开。
• 这一设计使得软体机器人可以根据环境变化动态改变自身结构，例如脱离受困部位或联合形成更长的身体以跨越障碍。
• 该研究为未来模块化、适应性强的软体机器人提供了新的思路和方法。
• 整体上，论文强调了高强度与易断开相结合的重要性，以实现多变且可靠的机器人系统。

实验细节补充

• 制造过程：将SIS与石蜡油混合后使其塑化，用糖颗粒制作出多孔结构，再将这种结构注入硅胶中，确保接头既柔软又坚固。
• 测试方法：通过T形剥离测试和循环负载测试验证了接头的性能，证明其在多次使用后依然具备足够强度。
• 加热过程：利用铜制加热器快速将接头加热至断开或重新连接所需的温度。
• 冷却：加热后接头冷却至室温，使融化的SIS固化，从而牢固地连接各部分。