Printable Hydraulics: A Method for Fabricating Actuated 3D-printed Assemblies


This technology is a novel multi-material 3D printing process for fabricating functional robots using 3D inkjet-based printers. This new printing capability enables complex hydraulically actuated robots and robotic components to be automatically built, with no assembly required, which allows for the fabrication of complex actuated structures that, assembled manually, would be inconvenient or impossible to produce.

Problem Addressed

Building robots is a time-consuming process as multiple discrete materials with long assembly times must be assembled sequentially. The mass-production of robots is impractical due to the costs of repeated design iterations and optimization steps. Multi-material additive manufacturing techniques, such as 3D printing, have emerged as a compelling method to fabricate robots. This approach allows materials with diverse mechanical properties to be placed at arbitrary locations within a structure, enabling the rapid fabrication of multi-part design iterations. The Inventors have developed one such multi-material 3D printing process that can fabricate functional, hydraulically actuated robotic structures in a single step.  


Printable Hydraulics is a novel fabrication process that simultaneously prints solid and liquid materials, depositing both photopolymers and a non-curing liquid concurrently to fabricate complex, pre-filled fluidic channels. The printable hydraulic parts are functional, hydraulically actuated assemblies that employ non-solidifying liquids as a force-transmitting component. These parts are printed in a single step using a multi-material inkjet printer that simultaneously fabricates solid and liquid regions within a structure. The printer deposits individual droplets of material in a layer-by-layer build process, wherein individual layers can contain one or more material types. Solids with varying stiffness are used to modulate the flexibility of various portions, enabling prescribed strain in response to applied fluid pressure. Supporting layers are provided either via removable curing support material or by non-curing liquid.


  • Solid and fluid regions are fabricated together, dramatically reducing fabrication times
  • Process enables complex geometries that are infeasible with other 3D printing methods
  • Simple control of complex hydraulic assemblies, relative to systems based on pneumatics
  • Printed hydraulics offer low-friction, low-backlash, and high force-transmission compared to other active 3D assemblies