Desktop fabrication of monolithic soft robotic devices with embedded fluidic control circuits

Most soft robots are pneumatically actuated and fabricated by molding and
assembling processes that typically require many manual operations and
limit complexity. Furthermore, complex control components (for example,
electronic pumps and microcontrollers) must be added to achieve even
simple functions. Desktop fused filament fabrication (FFF)
three-dimensional printing provides an accessible alternative with less
manual work and the capability of generating more complex structures.
However, because of material and process limitations, FFF-printed soft
robots often have a high effective stiffness and contain a large number of
leaks, limiting their applications. We present an approach for the design
and fabrication of soft, airtight pneumatic robotic devices using FFF to
simultaneously print actuators with embedded fluidic control components.
We demonstrated this approach by printing actuators an order of magnitude
softer than those previously fabricated using FFF and capable of bending
to form a complete circle. Similarly, we printed pneumatic valves that
control a high-pressure airflow with low control pressure. Combining the
actuators and valves, we demonstrated a monolithically printed
electronics-free autonomous gripper. When connected to a constant supply
of air pressure, the gripper autonomously detected and gripped an object
and released the object when it detected a force due to the weight of the
object acting perpendicular to the gripper. The entire fabrication process
of the gripper required no posttreatment, postassembly, or repair of
manufacturing defects, making this approach highly repeatable and
accessible. Our proposed approach represents a step toward complex,
customized robotic systems and components created at distributed
fabricating facilities.