Folding robots and metamaterials The same principles used to make origami art can self-assembling tunable metamaterials—artificial materials engineered have properties that may not be found in nature (see the Perspective by You). Felton et al. made complex self-folding from flat templates. Such could potentially sent through a collapsed building or tunnels then assemble themselves autonomously into their final functional form. Silverberg created mechanical metamaterial was folded tessellated...

Self-folding microscale origami patterns are demonstrated in polymer films with control over mountain/valley assignments and fold angles using trilayers of photo-crosslinkable copolymers a temperature-sensitive hydrogel as the middle layer. The characteristic size scale folds W = 30 μm figure merit A/ (2) ≈ 5000, here represent substantial advances fabrication self-folding origami.

Origami and kirigami have emerged as potential tools for the design of mechanical metamaterials whose properties such curvature, Poisson ratio, existence metastable states can be tuned using purely geometric criteria. A major obstacle to exploiting this property is scarcity identify program flexibility fold patterns. We exploit a recent connection between spring networks quantum topological origami with localized folding motions at boundaries study them both experimentally theoretically....

Patterning deformation within the plane of thin elastic sheets represents a powerful tool for definition complex and stimuli-responsive 3D buckled shapes. Previous experimental methods, however, have focused on that access limited number shapes pre-programmed into sheet, restricting degree dynamic control. Here, we demonstrate on-demand reconfigurable buckling poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM) hydrogel network films containing gold nanoparticles (AuNPs) by patterned...

We use numerical simulations to probe the dynamics of concentrated suspensions spherical microswimmers interacting hydrodynamically. Previous work in dilute limit predicted orientational instabilities aligned for both pusher and puller swimmers, which we confirm computationally. Unlike previous work, show that isotropic swimmers are also always unstable. Both types initial conditions develop long-time polar order, a nature depends on hydrodynamic signature swimmer but very weakly volume...

Origami-based design holds promise for developing materials whose mechanical properties are tuned by crease patterns introduced to thin sheets. Although there have been heuristic developments in constructing with desirable qualities, the bridge between origami and physics has yet be fully developed. To truly consider structures as a class of materials, methods akin solid mechanics need developed understand their long-wavelength behavior. We introduce here lattice theory examining...

Significance Shape-programmable structures have recently used origami to reconfigure using a smooth folding motion, but are hampered by slow speeds and complicated material assembly. Inspired natural systems like the leaves of Venus flytraps hummingbird beaks, we use curved creases imbue elastic shells with programmable fast “snapping” motion. This deformation between preprogrammed states can be tuned either continuously foldable or snap discontinuously. Our results provide purely...

Confinement and wall effects are known to affect the kinematics propulsive characteristics of swimming microorganisms. When a solid body is dragged through viscous fluid at constant velocity, presence increases drag, thus net force required maintain speed has increase. In contrast, recent optical trapping experiments have revealed that generated by human spermatozoa decreased boundaries. Here, we use series simple models analytically elucidate boundary on passively actuated filaments model...

Microrheological studies of phospholipid monolayers, bilayers, and other Langmuir monolayer systems are traditionally performed by observing the thermal fluctuations tracers attached to membrane or interface. Measurements this type obtain surface moduli that orders magnitude different from those obtained using macroscopic active techniques. These large discrepancies can result uncertainties in tracer's coupling local disruption tracer. To avoid such problems, we perform a microrheological...

Significance Cell shapes are related to their biological function. More generally, membrane morphology plays a role in the segregation and activity of transmembrane proteins. Here we show geometric implications regarding how cellular mechanics localizing thermal fluctuations on membrane. We theoretically that certain features curved shells control spatial distribution undulations. experimentally verify this theory using discocyte red blood cells find geometry alone is sufficient account for...

Abstract Patterning deformation within the plane of thin elastic sheets represents a powerful tool for definition complex and stimuli‐responsive 3D buckled shapes. Previous experimental methods, however, have focused on that access limited number shapes pre‐programmed into sheet, restricting degree dynamic control. Here, we demonstrate on‐demand reconfigurable buckling poly( N ‐isopropylacrylamide‐ co ‐acrylic acid) (PNIPAM) hydrogel network films containing gold nanoparticles (AuNPs) by...

Journal Article A rubber œsophagus Get access Arthur Evans, O.B.E. Surgeon Westminster Hospital, London Search for other works by this author on: Oxford Academic Google Scholar British of Surgery, Volume 20, Issue 79, January 1933, Pages 388–392, https://doi.org/10.1002/bjs.1800207904 Published: 09 December 2005

A non-contact microrheological technique to probe the mechanics of air/water interface is explored. Polystyrene spheres dissolved in water are trapped with an optical tweezer near free surface water, allowing response functions particles be measured as a function distance from interface. These measurements show that at surface, imaginary part increases by approximately 30% Stokes value bulk. As particle moved away via trap, returns bulk value. The method tested comparing rigid wall theory...

We investigate the dynamics of a dilute suspension hydrodynamically interacting motile or immotile stress-generating swimmers particles as they invade surrounding viscous fluid. Colonies aligned pusher are shown to elongate in direction particle orientation and undergo cascade transverse concentration instabilities, governed at small times by an equation that also describes Saffman-Taylor instability Hele-Shaw cell, Rayleigh-Taylor two-dimensional flow through porous medium. Thin sheets...

When a flexible filament is confined to fluid interface, the balance between capillary attraction, bending resistance, and tension from an external source can lead self-buckling instability. We perform analysis of this instability provide analytical formulae that compare favorably with results detailed numerical computations. The stability long-time dynamics are governed by single dimensionless elastocapillary number quantifying ratio stresses. Complex, folded configurations such as loops,...

The capillary assembly of stimulus-responsive hydrogel particles with programmed multipolar interactions defined by their prescribed three-dimensional (3D) shapes is demonstrated.

Wrinkling of thin films and membranes can occur due to various mechanisms such as growth and/or mismatch between the mechanical properties film substrate. However, physical origins dynamic wrinkling in soft are still not fully understood. Here we use milk skin a tractable experimental system investigate physics wrinkle formation thin, poroelastic film. Upon heating milk, micron-thick hydrogel denatured proteins fat globules forms at air-water interface. Over time, observe an increase total...

Significance Red blood cells are soft and pliable, which allows them to deform through small capillaries. We have found that red cells, if dispersed in a synthetic liquid crystal, squeezed into complex shapes via the viscoelastic environment created by crystal. The strained exhibited individual crystals reveal cell mechanical properties unmask high level of cell-to-cell variation across population cells. sharing strain between mammalian is general provides approaches for quantifying...

Microrheology relies on tracking the thermal or driven motion of microscopic particles in a soft material. It is well suited to study materials that have no three-dimensional realization, which makes them difficult using macroscopic rheometer. For this reason, microrheology becoming an important rheological probe Langmuir monolayers and membranes. Interfacial microrheology, however, has been reconcile quantitatively with more traditional approaches. We suggest uncertainties accounting for...

We present a theory of flexural wave propagation on elastic shells having nontrivial geometry and develop an analogy to geometric optics. The transport momentum within the shell itself is anisotropic due curvature, as such complex classical effects birefringence are generically found. determine equations reflection refraction waves at boundaries between different local geometries, showing that totally internally reflected, especially regions positive negative Gaussian curvature. verify these...

Motivated by recent advances in vesicle engineering, we consider theoretically the locomotion of shape-changing bilayer vesicles at low Reynolds number. By modulating their volume and membrane composition, can be made to change shape quasi-statically thermal equilibrium. When control parameters are tuned appropriately yield periodic changes which not time-reversible, result is a net swimming motion over one cycle deformation. For two classical models (spontaneous curvature coupling),...