Robust Soft-Matter Robotic Materials

Emerging applications in wearable computing, human-machine interaction, and soft robotics will increasingly

rely on new soft-matter technologies. These soft-matter technologies are considered inherently safe as

they are primarily composed of intrinsically soft materials—elastomers, gels, and fluids. These materials provide a method for creating soft-matter counterparts to traditionally rigid devices that exhibit the mechanical compliance and versatility of natural, biological systems. However, these soft-matter counterparts often rely on power and data communication tethers, limiting their use outside of a controlled laboratory environment. Furthermore, these soft-matter counterparts are increasingly susceptible (as compared to their rigid counterparts) to varying forms of mechanical damage such as cutting, tearing, or puncture that can result in operational failure. This thesis presents two new rapid (<3 hrs) fabrication methods that addresses current challenges of integrating surface mount microelectronics for signal processing, wireless communication, and power with soft and stretchable circuit interconnects. In addition, a new material architecture is introduced for creating soft and highly deformable circuit interconnects that are capable of autonomous electrical selfhealing to maintain electrical functionality when damage occurs. Finally, this material architecture can be

used as an artificial nervous tissue to electrically detect, localize, and respond to detrimental damage events

within soft-matter inflatable structures and robotic systems.

To enable soft-matter technologies to be useful outside of a controlled laboratory environment, the necessary

circuit components for signal processing, wireless communication, and power must be integrated.

Systems integration raises unique challenges in materials compatibility, multi-scale fabrication, and electrical

and mechanical interfacing. Here, a unifying, deterministic adhesive transfer approach was developed,

enabling precision multi-layer assembly of conductive and insulating thin films with surface mount integrated

circuits (Chapter 2). This method was demonstrated by fabricating two highly customizable wearable

devices that directly adhere to the skin. In addition, an anisotropic, Z-axis conductive film was developed

for interfacing liquid-phase interconnects with surface mount components (Chapter 3).

A major obstacle to the adaption of soft-matter technologies in more complex, natural environments outside laboratories is their fragility. Whereas natural biological tissue can quickly detect and adapt to

injuries, current soft-matter technologies often cannot circumvent even minor damage. Here, we introduce

a material architecture and framework for creating soft, stretchable circuit interconnects that are electrically

stable under typical operational loading conditions but capable of instantaneous electrical self-healing under

multiple, extreme damage events (Chapter 4). Circuits produced with this hybrid composite remain fully and

continuously operational even when the traces are severed, torn, punctured, or the material is completely

removed.

The ability of biological organisms to autonomously detect, communicate, and respond to damage of soft tissue presents an intriguing opportunity for compliant, engineered systems. Here, an artificial nervous

tissue has been developed for detecting and localizing mechanical damage events (Chapter 5). When coupled

with computation, communication, and actuation, this soft and highly deformable biomimetic composite presents new opportunities to autonomously identify damage, calculate severity, and respond to prevent

failure within robotic systems.