Bioinspired Machines

Soft Locomotive Robots

We have caused natural motion in synthetic robots by using organic elastomers (crosslinked polymers above their glass transition temperature) that deform continuously over large ranges of strain.
  • Large shape changes allow easy switching between gaits: walking or undulating.
  • The tough materials create robots capable of sustaining large impact forces without damage.
  • The robots can be scaled for a mission simply by increasing the size of the mold used to cast the rubber and choosing an appropriate elastic modulus for the material.
Relevant Publications:

Bicontinuous Liquid Metal Foams

We have developed a composite of two entangled foams: an elastomer and a low melting temperature metal, that exhibits dynamic shape morphing and shape memory actuation. Additionally, by melting and freezing the metal foam, the composites can both self-heal and be assembled into larger, continuous structures from smaller sub-components. The composite has been embedded into two soft robotic devices to demonstrate the capability for reversible stiffness in soft robots.
Relevant Publications:

Soft Cardiac Assist Devices

We are developing an entirely soft, fluid pumping device. Our pump is comprised of biocompatible materials and leverages elastomer foam in its inflation chambers. When these chambers are inflated with compressed air, an adjacent water-containing chamber is pressurized which generates flow. Our pump design uses two isolated foam inflation chambers. By alternating inflation of the chambers, we observe controlled pulsatile, unidirectional flow. We believe that, with further development, this device could find use as a ventricular assist device (VAD). Though this pump was molded to reflect the geometry of a human heart, it could function equally well in a variety of other shapes.
  • Generates up to 430 ml/min flow.
  • Pumps at physiological pressures (~105 mm Hg) and frequencies (60 – 120 BPM).
Relevant Publications:

Soft Orthotic Actuators

We applied rotational casting as a reliable and effective method for fabricating high force orthotics. We fabricated a wearable assistive device for increasing the force a user can apply at their fingertips. To better improve the functionality of the hand orthotics, we also demonstrated the monolithic integration of solid-state optical light-guides for curvature sensing in them. Besides fabrication and integration, we have also realized feedback control of FEAs using the embedded sensors.
  • Relatively large applied forces at finger tip.
  • Safe human-machine interaction.
Relevant Publications:

High-DOF, 3D-Printed Fluidic Actuators

Using our custom DMP-SL printer, we can quickly fabricate high resolution actuators from soft materials. Inspired by the complex three-dimensional arrangement of muscles in octopus tentacles, we have designed soft machines that incorporate multiple actuators into a monolithic, printed structure. These antagonistic pairs allow the printed tentacle to actuate over a wide range of motion. As shown in the video to the right, multiple antagonistic pairs can be combined to create complex, 3D motions.
  • High-DOF actuators can be quickly prototyped as a monolithic structure.
  • High speed actuation with periods of less than 70ms.
  • Working pressures greater than 345 kPa (50 psi).
Relevant Publications: