A Pneumatic Artificial Muscle Manufactured Out of Self-Healing Polymers That Can Repair Macroscopic Damages

Abstract

Pneumatic muscles are mostly constructed out of flexible membranes and are implemented in a wide range of robotic applications. In these soft materials, perforations are often caused by overpressuring of the muscles and wear. In many cases this leads to limited numbers of actuation cycles. In this paper, pleated pneumatic artificial muscles were developed, whose membrane is constructed out of self-healing polymer. This allows for the complete healing of microscopic and macroscopic damages through a mild heat treatment. Two prototypes were designed, manufactured and experimentally characterized. The self-healing was validated by repairing relatively large cuts in the muscle membrane completely. Even when repeatedly damaging and healing the muscles, the mechanical properties were recovered in a reversible and repeatable fashion through the self-healing procedure.

Additive Manufacturing for Self-Healing Soft Robots

“…There are several ways the gelation (solidification) of the DA materials can be improved. In this study, a six-functional furan compound (FT5000) is used, which has a lower gel conversion x gel than the four-functional compound used in previous studies 16,17 and thus has a higher T gel and solidifies faster. Keeping all constraints in mind, the self-healing DA material DPBM-FT5000 in stoichiometric ratio (R ¼ n maleimide n furan ¼ 1) was selected for this application.…”

“…14,15 In prior study, the authors developed the first demonstrators of selfhealing soft robotics, including soft grippers, soft hands, and artificial muscles. 16,17 These actuators have shown a recovery of up to 98% 16 after severe damage, leaving no weak spots.…”

Autonomous self-healing hydrogel with anti-drying properties and applications in soft robotics

“…Thus, SHAP was used for the development of a pneumatic artificial muscle (PAM) [42] because, as previously mentioned, the main advantages of this material are: (i) its stability under ambient conditions, since the hydrogel remains soft over time without drying; (ii) its viscoelastic properties; (iii) its self-healing ability under ambient conditions without the need for an external stimulus. This last feature is a crucial advantage when compared, for instance, to the healable material reported by Terryn et al, [75] who presented a variant of PAM muscle made of Diels-Alder polymer that was able to self-heal on applying heat, i.e., an external stimulus is required for the self-healing process to be initiated (non-autonomous self-healing material).…”

Self-Healing and Damage Resilience for Soft Robotics: A Review

“…The 3D printing process trapped liquid resin in the elastomer; when the robot was punctured, the excess resin was able to seal up the holes if given sufficient UV stimulus (such as direct sunlight). Terryn et al (2015Terryn et al ( , 2017a have taken a different approach to resilient pneumatic actuators by shaping self-healing polymers into inflatable chambers. In their early work, they molded a single, thin-walled cube out of a thermally responsive self-healing polymer and demonstrated its inflation capacity, even after catastrophic failure (Terryn et al, 2015).…”

“…Most recently, Terryn et al (2017b) demonstrated that by patterning these cubes adjacent to one other, the extended system could be utilized as a soft robotic bending actuator capable of grasping objects. In another recent work, the researchers utilized this same self-healing material to create a pneumatically actuated artificial muscle that can contract over 10% of its length (Terryn et al, 2017a).…”