Compliant Buckled Foam Actuators and Application in Patient-Specific Direct Cardiac Compression

Abstract

We introduce the use of buckled foam for soft pneumatic actuators. A moderate amount of residual compressive strain within elastomer foam increases the applied force ∼1.4 × or stroke ∼2 × compared with actuators without residual strain. The origin of these improved characteristics is explained analytically. These actuators are applied in a direct cardiac compression (DCC) device design, a type of implanted mechanical circulatory support that avoids direct blood contact, mitigating risks of clot formation and stroke. This article describes a first step toward a pneumatically powered, patient-specific DCC design by employing elastomer foam as the mechanism for cardiac compression. To form the device, a mold of a patient's heart was obtained by 3D printing a digitized X-ray computed tomography or magnetic resonance imaging scan into a solid model. From this model, a soft, robotic foam DCC device was molded. The DCC device is compliant and uses compressed air to inflate foam chambers that in turn apply compression to the exterior of a heart. The device is demonstrated on a porcine heart and is capable of assisting heart pumping at physiologically relevant durations (∼200 ms for systole and ∼400 ms for diastole) and stroke volumes (∼70 mL). Although further development is necessary to produce a fully implantable device, the material and processing insights presented here are essential to the implementation of a foam-based, patient-specific DCC design.

Bio‐inspired Design and Additive Manufacturing of Soft Materials, Machines, Robots, and Haptic Interfaces

“…[146,148,149] Since soft robots have as imilar elastic modulus as many biological tissues,t hey can also be built to safely and effectively assist or even replace human tissues. [92,94,[150][151][152][153] Thef ield of bio-inspired soft robots keeps advancing as our understanding of physiology and functional morphology increases. [154] Moreover,nature produces complicated designs of organisms at so little cost of energy.…”

“…[152] with permission from Wiley.e)Direct cardiac compression (DCC) based on ab uckled foam actuator.R eproducedfrom Ref. [153] with permission from Mary Ann Liebert, Inc. publishers. f) Prosthetic hand with ahigh force and high speed enabled by 3D printed elastomeric passive transmissions (EPTs).…”

“…[153] Thes ame group improved the design by buckling the foam before sealing with elastomer, and achieved augmented actuation in aventricular assist device for direct cardiac compression (DCC;F igure 7e). [153] This system shows important features for aD CC device that had not been achieved before:p atient-specific design with programmable local compression, which eliminates the potential adverse compression of coronary arteries. Molded out of a3 Dp rinted CT-reconstructed heart model, the DCC device realizes this function with little increased fabrication complexity and cost:the active DCC area (where the DCC device contacts the ventricle exterior) is patterned with inflatable foams,a nd the passive area (where the DCC device contacts the coronary artery) is coated with an inextensible polyurethane elastomer.…”

Bioinspiriertes Design und additive Fertigung von weichen Materialien, Maschinen, Robotern und haptischen Schnittstellen

“…B. Cephalopodententakel und Elefantenrüssel) . Da weiche Roboter einen ähnlichen Elastizitätsmodul wie viele biologische Gewebe aufweisen, können sie auch konstruiert werden, um menschliche Gewebe sicher und effektiv zu unterstützen oder gar zu ersetzen . Das Gebiet der bioinspirierten weichen Roboter schreitet im Zuge der immer tieferen Einblicke in die Physiologie und Funktionsmorphologie stetig weiter voran…”

“…Abdruck aus Lit. , mit Genehmigung von Mary Ann Liebert, Inc. publishers. f) Prothesenhand, die durch mittels 3D‐Druck hergestellte EPTs eine große Kraft und eine hohe Geschwindigkeit erreicht.…”