An Artificial Motion and Tactile Receptor Constructed by Hyperelastic Double Physically Cross‐Linked Silk Fibroin Ionoelastomer

Abstract

Ionotronic artificial motion and tactile receptor (i-AMTR) is essential to realize an interactive human-machine interface. However, an i-AMTR that effectively mimics the composition, structure, mechanics, and multi-functionality of human skin, called humanoid i-AMTR, is yet to be developed. To bridge this technological gap, this study proposes a strategy that combines molecular structure design and function integration to construct a humanoid i-AMTR. Herein, a silk fibroin ionoelastomer (SFIE) with double cross-linked molecular structure is designed to mimic the composition and structure of human skin, thereby resolving the conflict of stretchability, softness, and resilience, suffered by many previously reported ionotronics. Functionally, electromechanical sensing and triboelectricity-based tactile perception are integrated into SFIE, to enable simultaneous perception of both motion and tactile inputs. By further leveraging the machine learning and Internet of Things (IoT) techniques, the proposed SFIE-based humanoid i-AMTR precisely senses the movement of human body and accurately sortball objects made of different materials. Notably, the success rate for 610 sorting tests reaches as high as 92.3%. These promising results essentially demonstrate a massive potential of humanoid i-AMTR in the fields of sorting robots, rehabilitation medicine, and augmented reality.

3D Printing Silk Fibroin/Polyacrylamide Triple-Network Composite Hydrogels with Stretchability, Conductivity, and Strain-Sensing Ability as Bionic Electronic Skins

“…In this work, silk microfiber (SMF)/regenerated silk fibroin (RSF)/PAM triple-network composite hydrogels exhibiting excellent properties, such as stretchability, conductivity, strain-sensing ability, and 3D printability, were fabricated based on a simple white source curing method. The SF component and the cross-linked RSF hydrogel provide the advantages of good biocompatibility and biodegradability, which make SF one of the ideal natural materials for electronic skins. − The PAM hydrogel has been reported to have excellent stretchability and strain-sensing ability . The addition of negatively charged SMF enhances the mechanical properties, conductivity, and sensing ability of hydrogels due to the interaction between SMF and RSF and the adsorption of cations.…”

Knitting from Nature: Self-Sensing Soft Robotics Enabled by All-in-One Knit Architectures

“…Decades of industrial development and scientific research have led to increasing use of robotics in daily life and engineering tasks. – This field has become extremely active with the recent developments of soft pneumatic robotics that have excellent deformability, adaptability in unstructured environments and safety for human–machine interaction due to their inherent softness. – To further extend the capabilities of these soft robotics, sensorized actuators that can respond to external stimuli and sense self-deformation by mimicking biological systems are desirable. Efforts in self-sensing robotics have combined soft actuators with flexible sensors to either ensure a stable and self-adaptive deformation in response to the surrounding environment or use the information generated by the sensors to accurately regulate the control system for actuation. – However, recent soft robotics have difficulties in ideally matching with conventional add-on sensors, generally suffering from incompatible surface interaction, poor connection, along with possible stress concentration, and manufacturing complexity. – …”

Skin-Inspired Patterned Hydrogel with Strain-Stiffening Capability for Strain Sensors

“…The skin is initially soft but adaptively stiffens by several orders of magnitude to maintain its structural integrity at elevated deformations . This strain-stiffening behavior enables the skin to possess unparalleled combinations of mechanical properties (e.g., low Young’s modulus and high strength), which is attributed to the hierarchical structure of the skin, consisting of rigid collagen fibers for resisting deformation and interwoven elastin fibers for ensuring elastic recoil. , Therefore, mimicking the modulus-contrast hierarchical structure of biological tissues by integrating elastic and stiff domains into the matrix is a straightforward strategy to endow soft materials with strain-stiffening capability. , To date, a variety of biomimetic materials with strain-stiffening capability that were constructed by embedding stiff domains in the soft matrix have been investigated, such as aligned nanofibrillar architectures, , stretchable geometric structures, , semiflexible polymer networks, and segregated microphases. − Despite great advances, there are still certain limitations associated with these biomimetic materials such as Young’s modulus in the initial stage higher than those of most biological tissues or the absence of conductive capability, which further restrict their applications as robust sensing materials.…”