Progress and Roadmap for Intelligent Self‐Healing Materials in Autonomous Robotics

Abstract

self-repair in order to survive and thrive. Soft to hard tissues can self-regenerate when injured, including the skin and bones. [6] Some of the living tissues, such as nails and bones, can even continuously remodeling themselves, removing the damaged tissues unintentionally and replaced by newly grown tissues. However, unlike regenerative and remodeling capabilities in nature, robots are made from nonliving synthetic materials such as polymers and metals. Hence, as we develop robots to have greater autonomy and capabilities, having the ability to self-heal or self-repair is becoming more critical, if not, essential, especially from an environmental sustainability point of view. [2,[7][8][9][10][11] The term self-healing materials, also often referred to as self-mending or selfrepairing materials, are materials that can regain some or most of its original material properties when damaged. In synthetic materials, the self-healing materials repair their damage without regenerative origins. As these selfhealing materials undergo self-repair, they regain their original intended functions through the recovery of the desired material properties, without an increase in original mass.As the number of self-healing materials is growing at a rapid clip, we first establish a brief history in this review to help the reader gain a broader perspective on self-healing materials. We emphasize on self-healing materials that recover their mechanical properties, because mechanical properties often dictate the possible applications. Figure 1 highlights the various selfhealing materials from high modulus to low modulus materials that can be used for robotic applications.There are two broad classifications for self-healing materials: a) autonomic versus nonautonomic self-healing materials; b) intrinsic versus extrinsic self-healing. [8] These self-healing materials can recover their properties either autonomously, i.e., without significant external intervention, much like human tissues; or they can also heal with external intervention, such as when some external environment changes cause temperature increment or via various triggers such as mechanical stimuli. Intrinsic self-healing materials do not need external healing agents, while extrinsic self-healing materials contain external healing agents for the healing of the matrix materials. In addition to those classifications, we will provide new insights on classifying these materials further into this review.In Section 2, we discuss various types of smart biomimetic robots where self-healing materials can be beneficial. Section 3 Robots are increasingly assisting humans in performing various tasks. Like special agents with elite skills, they can venture to distant locations and adverse environments, such as the deep sea and outer space. Micro/nanobots can also act as intrabody agents for healthcare applications. Self-healing materials that can autonomously perform repair functions are useful to address the unpredictability of the environment and the increasing drive toward the autonom...

Smart Table Tennis Racket with Tunable Stiffness for Diverse Play Styles and Unconventional Technique Training

“…Xuefeng Zhou, Lijuan Wang, Dongyang Huang, Yudai Liang, Quan Shi, Hong Yaying, Mengying Zhang,* Huayan Pu, Weijia Wen, and Jinbo Wu* DOI: 10.1002/admt.202100535 have been made from smart materials, assisting humans in performing various tasks and even replacing their organs. [6][7][8] Table tennis is a worldwide known sport for more than 100 years appearing not only in public life but also in international events. [9,10] In daily exercise, as individual power, speed and style change with ages, the requirement for table tennis rackets with racket face of different hardness cannot be met by one or two rackets.…”

Composites of functional polymers: Toward physical intelligence using flexible and soft materials

“…Common methods to synthesize self-healing materials include incorporating monomers that are released and react at the site of fracture and synthesizing networks that contain reversible covalent bonds. Many self-healing polymers that incorporate reversible covalent bonds into the polymer network require heating for full and/or fast healing [112]. Active heating and healing (e.g., at higher temperatures) can be achieved by a single material when self-healing polymers are processed as composites.…”

Processing of Self‐Healing Polymers for Soft Robotics

“…Recently, the solution has been proposed to make soft robots out of self-healing polymers. [20][21][22][23][24] These self-healing polymers [25] have the intrinsic ability to heal microscopic and macroscopic damage and recover their functional performance, either fully autonomously, without the need of any external intervention, or by means of an external stimulus, for example, heat or light. Researchers have proven that this self-healing concept in soft robotics is not only useful in pneumatic, [26,27] electrostatic, [28] tendon driven, [29] or even passive actuators, [30] but also in their electronics [31] and sensors.…”