From mimosa pudica to responsive panels for architecture, the research at MaBa.SAPERLab

The mimosa pudica’s journey is a long one. This evergreen plant, native to Central America, landed in the DABC MaBa.SAPERLab – Department of Architecture, Built Environment, and Construction Engineering – where Fabio Bazzucchi, first as a visiting researcher from MIT in Boston (where he was as a Postdoctoral Fellow Marie Skłodowska-Curie at the Senseable City Lab) and now as a researcher at the university, under the guidance of the department’s scientific coordinator, Ingrid Paoletti, is studying the properties of this unique plant for the design of dynamic and responsive architectural elements.

Mimosa pudica (aka sensitive plant) is truly unique and has fascinated researchers and scholars in every field for centuries: from Charles Darwin to Robert Hooke, father of Hooke’s law of elasticity. The reason for this interest can be found in the plant’s name: indeed, it is called ’sensitive’ because it folds back its leaves if a foreign body comes close to it and, if touched, it closes them following a precise pattern, in pairs – and even, in extremis, instantaneously fully closes them if, for example, it is dropped. These reactions are unexpected in a plant organism and many different interpretations have been suggested, all valid but so far none conclusive: the first that comes to mind, of course, is that it is a self-defence mechanism, of which, moreover, the plant appears to retain a memory.

These observations, before this research got underway, were the premises of the co-authored article published in 2023 by Bazzucchi and Ingrid Paoletti, who had previously discussed their respective studies and mutual interest in mimosa pudica. «The current state of the art of this plant’s description does not take into account the snap hypothesis. Instead, Professor Paoletti and I began to study whether, at the macro level, the movement could be considered a snap, that is, a loss of stability – a transition between two states of equilibrium. In our article, we discussed whether this could be taken as an interpretative model of its movements. I am a civil engineer, my doctoral thesis dealt with issues linked to very slender structures, close to the mechanics of materials, and Professor Paoletti was keen to understand if these systems could have practical implications for architecture. So, during our research, we focused on the mechanics of the plant itself. We began with a mathematical study that we used in the following phase of the study: we devised a model in which we imagined that the plant’s “intelligence” resides in its material organisation, in how it grew and developed, and above all, adapted. Its tissues are arranged in such a way that it can be intelligent in its environment. And since the MaBa.SAPERLab laboratory studies materials in their broadest sense, we are attempting to explore how materiality and intelligence can somehow merge. Because our brain also has a shape, folds, that are functional to its purpose, so the key to interpreting the capabilities and intelligence of the plant, whose tissues we are now studying, lies in the arrangement of the material. The idea is to create architectural elements that are responsive or sensitive to the environment, so-called smart materials that respond, like mimosa pudica, to stimuli such as light, heat, shock, touch».

So how could the materials obtained in this way be used? «We imagined surfaces that change shape rapidly, panels whose surface or texture can rapidly change their configuration. This could be useful for tactile experiences, but also to create acoustic, visual or perceptual comfort in general. Because static shapes and geometries are very stressful for the human brain, like being in an environment where nothing ever changes, which is anything but natural. At the start we devised a sound-absorbing, responsive panel, because snap systems are often used for shock-absorbers, i.e. systems that absorb a shock through successive snaps. But the possibilities are endless».

The next step is the 3D printing of a module prototype: «The mathematical studies were carried out with a view to understanding if an interpretative model involving a snap could be used to understand and reproduce it – continues Bazzucchi – A snap is a tuned mechanism, it is a system that passes from one configuration to another, while a gradual movement is as if it were stable at every point. Using this mechanism, the surfaces we are attempting to develop can undergo a sudden, immediate change; the next goal is not to achieve a simple on-off position like that of the plant, but to create surfaces that could perhaps have even up to 10 configurations, and we are working on patents in this regard».