Katia Bertoldi

Katia Bertoldi
Harvard University | Harvard · School of Engineering and Applied Sciences

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255
Publications
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14,866
Citations

Publications

Publications (255)
Article
Full-text available
Inflatable structures have become essential components in the design of soft robots and deployable systems as they enable dramatic shape change from a single pressure inlet. This simplicity, however, often brings a strict limitation: unimodal deformation upon inflation. Here, multistability is embraced to design modular, inflatable structures that...
Article
Full-text available
Living cilia stir, sweep and steer via swirling strokes of complex bending and twisting, paired with distinct reverse arcs1,2. Efforts to mimic such dynamics synthetically rely on multimaterial designs but face limits to programming arbitrary motions or diverse behaviours in one structure3–8. Here we show how diverse, complex, non-reciprocal, strok...
Article
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The locomotion of soft snake robots is dependent on frictional interactions with the environment. Frictional anisotropy is a morphological characteristic of snakeskin that allows snakes to engage selectively with surfaces and generate propulsive forces. The prototypical slithering gait of most snakes is lateral undulation, which requires a signific...
Article
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Across fields of science, researchers have increasingly focused on designing soft devices that can shape-morph to achieve functionality. However, identifying a rest shape that leads to a target 3D shape upon actuation is a non-trivial task that involves inverse design capabilities. In this study, a simple and efficient platform is presented to desi...
Article
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Topology optimization is used to design phononic bandgap materials that are tunable by mechanical deformation. A periodic media is considered, which due to the assumption of length scale separation, allows the dispersion relations to be obtained by analyzing a single unit cell subjected to Floquet-Bloch boundary conditions. A finite macroscopic def...
Article
Locomotion of soft robots typically relies on control of multiple inflatable actuators by electronic computers and hard valves. Soft pneumatic oscillators can reduce the demand on controllers by generating complex movements required for locomotion from a single, constant input pressure, but either have been constrained to low rates of flow of air o...
Article
In recent years, the ability to propagate topological solitons in mechanical metamaterials has unlocked unpaved paths towards potential applications in wave propagation, mechanical logic, and shape morphing. Here, we demonstrate how a multistable metamaterial can harness topological solitons with coupled rotational and translational components and...
Article
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Architected materials typically maintain their properties throughout their lifetime. However, there is growing interest in the design and fabrication of responsive materials with properties that adapt to their environment. Toward this goal, a versatile framework to realize thermally programmable lattice architectures capable of exhibiting a broader...
Article
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Porous materials with well-defined periodicity are commonly encountered in biological and synthetic structures and exhibit a wide range of behaviors, ranging from negative Poisson’s ratios, to high energy absorption and acoustic damping. Recently, the response of these systems has been shown to be enhanced by mechanical instabilities that lead to s...
Preprint
Full-text available
Recently, inflatable elements integrated in robotics systems have enabled complex motions as a result of simple inputs. However, these fluidic actuators typically exhibit unimodal deformation upon inflation. Here, we present a new design concept for modular, fluidic actuators that can switch between deformation modes as a response to an input thres...
Article
Full-text available
Inflatable robots are becoming increasingly popular, especially in applications where safe interactions are a priority. However, designing multifunctional robots that can operate with a single pressure input is challenging. A potential solution is to couple inflatables with passive valves that can harness the flow characteristics to create function...
Article
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Geometric reconfigurations in cellular structures have recently been exploited to realize adaptive materials with applications in mechanics, optics, and electronics. However, the achievable symmetry breakings and corresponding types of deformation and related functionalities have remained rather limited, mostly due to the fact that the macroscopic...
Article
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Programmable Anisotropic Transformations In article number 2105024, Joanna Aizenberg, Katia Bertoldi, and co-workers report that by programming independently anisotropy at the molecular and structural levels, unprecedented director-determined symmetry breaking can be realized in microcellular structures made of liquid crystalline elastomers (LCEs)....
Article
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From the discovery of functionally graded laminated composites, to near-structurally optimized diagonally reinforced square lattice structures, the skeletal system of the predominantly deep-sea sponge Euplectella aspergillum has continued to inspire biologists, materials scientists and mechanical engineers. Building on these previous efforts, in th...
Article
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Fluidic actuation in soft robots traditionally requires a complex assemblage of pumps, regulators, valves, and sensors, often resulting in large and bulky support systems. This added bulk can often hinder a robot's ability to be untethered, perform complex tasks, or bring challenges when it comes to maintenance or upgradeability. To address these l...
Article
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Inspired by the recent success of buckling-induced reconfigurable structures, a new class of deployable systems that harness buckling of curved beams upon a rotational input is proposed. First, experimental and numerical methods are combined to investigate the influence of the beam's geometric parameters on its non-linear response. Then, it is show...
Article
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Deployable Structures In article number 2101144, Martin Bechthold, Katia Bertoldi, and co‐workers present a system of curved beams that leverage material elasticity and out‐of‐plane buckling to deploy from flat to diverse 3D configurations with a simple rotational input. The platform provides opportunities for the generation of functional, deployab...
Article
Flexible mechanical metamaterials are compliant structures engineered to achieve unique properties via the large deformation of their components. While their static character has been studied extensively, the study of their dynamic properties is still at an early stage, especially in the nonlinear regime induced by their high deformability. Neverth...
Article
Biological systems have a remarkable capability of synthesizing multifunctional materials that are adapted for specific physiological and ecological needs. When exploring structure–function relationships related to multifunctionality in nature, it can be a challenging task to address performance synergies, trade-offs, and the relative importance of...
Article
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Nonreciprocity can be passively achieved by harnessing material nonlinearities. In particular, networks of nonlinear bistable elements with asymmetric energy landscapes have recently been shown to support unidirectional transition waves. However, in these systems energy can be transferred only when the elements switch from the higher to the lower e...
Article
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From stadium covers to solar sails, we rely on deployability for the design of large-scale structures that can quickly compress to a fraction of their size1–4. Historically, two main strategies have been used to design deployable systems. The first and most frequently used approach involves mechanisms comprising interconnected bar elements, which c...
Article
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Jamming is a structural phenomenon that provides tunable mechanical behavior. A jamming structure typically consists of a collection of elements with low effective stiffness and damping. When a pressure gradient, such as vacuum, is applied, kinematic and frictional coupling increase, resulting in dramatically altered mechanical properties. Engineer...
Article
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The fundamental topology of cellular structures—the location, number and connectivity of nodes and compartments—can profoundly affect their acoustic1–4, electrical⁵, chemical6,7, mechanical8–10 and optical¹¹ properties, as well as heat1,12, fluid13,14 and particle transport¹⁵. Approaches that harness swelling16–18, electromagnetic actuation19,20 an...
Preprint
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The quest for an advanced soft robotic actuator technology that is fast and can execute a wide range of application-specific tasks at multiple length scales is still ongoing. Here, we demonstrate a new design strategy leveraging the concepts of miniaturisation and fibre-reinforcement to realize high-speed inflatable actuators exhibiting diverse mov...
Article
Mechanical deformation has recently emerged as a promising platform to realize optical devices with tunable response. While most studies to date have focused on the tuning of the focal length, here we use a combination of experiments and analyses to show that an applied tensile strain can also largely reduce spherical aberration. We first demonstra...
Article
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The predominantly deep-sea hexactinellid sponges are known for their ability to construct remarkably complex skeletons from amorphous hydrated silica. The skeletal system of one such species of sponge, Euplectella aspergillum, consists of a square-grid-like architecture overlaid with a double set of diagonal bracings, creating a chequerboard-like p...
Article
Flexible mechanical metamaterials have been recently shown to support a rich nonlinear dynamic response. In particular, it has been demonstrated that the behavior of rotating-square architected systems in the continuum limit can be described by nonlinear Klein-Gordon equations. Here, we report on a general class of solutions of these nonlinear Klei...
Article
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Multi-welled energy landscapes arising in shells with nonzero Gaussian curvature typically fade away as their thickness becomes larger because of the increased bending energy required for inversion. Motivated by this limitation, we propose a strategy to realize doubly curved shells that are bistable for any thickness. We then study the nonlinear dy...
Article
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Domain walls, commonly occurring at the interface of different phases in solid-state materials, have recently been harnessed at the structural scale to enable additional modes of functionality. Here, we combine experimental, numerical, and theoretical tools to investigate the domain walls emerging upon uniaxial compres- sion in a mechanical metamat...
Article
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Gas turbine blades are subjected to unusually harsh operating conditions—rotating at high velocities in gas streams whose temperature can exceed the melting temperature of the blade. In order to survive these conditions, the blade must efficiently transfer heat to an internal cooling flow while effectively managing mechanical stresses. This work de...
Preprint
Full-text available
Nonreciprocity can be passively achieved by harnessing material nonlinearities. In particular, networks of nonlinear bistable elements with asymmetric energy landscapes have recently been shown to support unidirectional transition waves. However, in these systems energy can be transferred only when the elements switch from the higher to the lower e...
Article
Full-text available
Kirigami, the Japanese art of paper cutting, has recently enabled the design of stretchable mechanical metamaterials that can be easily realized by embedding arrays of periodic cuts into an elastic sheet. Here, kirigami principles are exploited to design inflatables that can mimic target shapes upon pressurization. The system comprises a kirigami s...
Article
Full-text available
In article number 2001863, Katia Bertoldi and co‐workers fabricate the first programmable kirigami balloons: soft devices that can be automatically designed to morph into a target shape upon inflation. This work provides a new platform for shape‐morphing devices that could support the design of innovative medical tools, actuators, and reconfigurabl...
Article
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Falls and subsequent complications are major contributors to morbidity and mortality, especially in older adults. Here, by taking inspiration from claws and scales found in nature, we show that buckling kirigami structures applied to footwear outsoles generate higher friction forces in the forefoot and transversally to the direction of movement. We...
Preprint
Kirigami, the Japanese art of paper cutting, has recently enabled the design of stretchable mechanical metamaterials that can be easily realized by embedding arrays of periodic cuts into an elastic sheet. Here, we exploit kirigami principles to design inflatables that can mimic target shapes upon pressurization. Our system comprises a kirigami shee...
Article
Fluidic soft actuators are enlarging the robotics toolbox by providing flexible elements that can display highly complex deformations. Although these actuators are adaptable and inherently safe, their actuation speed is typically slow because the influx of fluid is limited by viscous forces. To overcome this limitation and realize soft actuators ca...
Article
We investigate experimentally and numerically the response of hinged shallow arches subjected to a transverse midpoint displacement. We find that this simple system supports a rich set of responses, which, to date, have received relatively little attention. We observe not only the snapping of the arches to their inverted equilibrium configuration,...