Why a box of office staples may point to the buildings of the future

A handful of office staples does not look like the raw material of tomorrow’s engineering revolution. Yet compress them into a dense clump and something remarkable happens: the bundle starts to behave less like a pile of separate objects and more like a coherent material. Pull it apart and it resists. Shake it in the right way and the mass suddenly loosens, flowing back into individual pieces. Engineers at the University of Colorado Boulder have turned that everyday oddity into a serious materials question: can geometry alone create substances that are strong, adaptable and reversible?

The answer, so far, appears to be a hesitant ‘yes’. The Colorado team has been studying “entangled” particles – small components that mechanically hook into one another rather than being glued, welded or chemically bonded. Their work suggests that the shape of a particle can transform a loose granular material into something with an unusual combination of tensile strength, extensibility and toughness. In simulations and physical “pick-up” tests, the researchers found that a simple two-legged particle, shaped rather like a staple, produced especially strong interlocking behaviour. Change the geometry of the particle and the bulk material changes its character too.

Boosting tensile loads

That is significant because ordinary granular materials such as sand are excellent under compression but notoriously poor in tension. Sand grains can press against each other, but they do not reliably latch together. Staple-like particles react in a similar way. The Colorado group’s modelling indicates that tensile loads in these entangled materials are carried through a small number of dynamic force chains, which continually break and reform as the structure is stressed. In other words, the material is not rigid in the traditional sense. It is more like a constantly renegotiated truce between many tiny hooks. That gives it a curious dual nature: it can be resistant and load-bearing, yet it is still capable of being reconfigured.

The most intriguing feature may be that the material can be switched between more solid-like and more fluid-like states using vibration. Gentle mechanical agitation can encourage particles to settle into stronger entanglement, while stronger or differently tuned vibrations can make the structure unravel. This places the material in an interesting category between conventional solids and loose grains. It is not a liquid, but it is not a fixed solid either. Instead, it is a mechanically programmable assembly, with properties that depend on history, movement and particle architecture.

Creating a sustainable construction industry

The obvious question is what such a material might be good for? One possibility is sustainable construction. Imagine temporary walls, arches or shelters assembled from entangled particles that can later be taken apart without demolition and reused in a different form. Another is impact management, where a structure might need to be stiff in one situation and energy-dissipating in another. There is also a robotics angle. The Colorado researchers themselves have raised the possibility that many small units could one day lock together to perform a task and then separate again when it is complete – an idea that sounds theatrical, but which sits squarely inside several active fields of engineering research.

That broader context is where Canadian research becomes especially relevant. At McGill University, researchers working on architected metamaterials have been developing shape-shifting structures inspired by kirigami and origami. In one 2025 advance, the team showed how carefully designed cuts and internal geometries can produce metamaterials that morph into different stable shapes rather than merely stretching uniformly. The same group has also highlighted applications spanning deployable structures, soft robotics and adaptive mechanical systems. The common theme with the Colorado staples is that function is being engineered through shape and arrangement, not simply through the chemistry of the base material.

McGill’s work goes further still. Publications from Damiano Pasini’s group describe “entangled multistable origami” with reprogrammable stiffness amplification and damping, as well as curved origami shells with reprogrammable rigidity. These are different systems from the staple-like particles, but philosophically they belong to the same family: materials designed to move between states, store mechanical information and change behaviour under controlled loading. Together they suggest that the future of materials science may involve making matter less static and more computational – built not just to bear loads, but to respond, adapt and transform.

Connecting Canadian robotics

Canada is also active on the robotics side of the equation. The University of Toronto has long-running work in swarm robotics, including its modular mROBerTO platform for studying collective behaviour in many small robots. The university’s Microrobotics Lab is pushing similar ideas at much smaller scales, developing miniature wireless robots for applications in manufacturing and medicine. These are not entangled staple-materials, but they show that the notion of many simple units combining into a useful larger system is already an engineering reality. The leap from “robot swarm” to “material swarm” is no longer a purely speculative one.

There is even a particularly close Canadian parallel in granular behaviour. A recent McGill thesis examined how dry granular materials can be locally fluidised using vibration for robotic applications, including adaptive manipulation. That work touches the same conceptual nerve as the Colorado study: how can a material be made to switch, on demand, from jammed and load-bearing to mobile and easily reconfigured? Such switching behaviour is central to soft gripping, locomotion and morphing devices, and it provides a plausible bridge between basic granular physics and future machines.

None of this means that cities will soon be built from giant boxes of smart staples. Scaling, manufacturing, fatigue, control and long-term reliability remain major challenges. But the larger message is harder to dismiss. Materials science is moving beyond the idea that a material should have just one fixed identity. The more compelling prospect is of matter that can be assembled, strengthened, softened, reshaped and reused by design. In that sense, the humble staple may have pointed researchers towards something bigger: a world in which materials behave less like passive substances and more like systems with options.