Inflatable origami inspired by Mimosa Pudica, the ‘folding plant’

The study of inflatable origami derived from the investigation of the Mimosa Pudica plant, which closes its leaflets when disturbed. The leaves fold inward and droop when touched or shaken, defending themselves from harm, and re-open a few minutes later. When the leaves are folded it makes the plant appear smaller, whilst simultaneously exposing sharp spikes on its stem.

Mimosa Pudica structure
Stimuli which causes Mimosa Pudica leaflets to fold
Change of turgor pressure within cells to cause leaflets to close

The plant folds its leaves as a result of a small change of turgor pressure in the plant cells which regulates the significant movement of the leaflets. In order to investigate this pressure change through modelling, two balloons are used and positioned at the base of the fins, mimicking the pressure change of the Mimosa Pudica. The model displays how a small increase of pressure, in this instance air, can create a more significant movement, acting as a hinge.

To control the angles of the tilt, a balloon has been made from paper using a tailored origami template which tilt the fins forward and inwards, replicating that of the Mimosa Pudica leaf movement. The origami balloon is comprised of two hinges, each one tilting in a different direction. When inflated, the first hinge expands, tilting the connecting fin forwards. When more air is blown into the balloon, the second hinge is inflated, tilting the fin inwards.

Origami balloon inflation sequence

As shown above, the origami balloons can control the desired angles of the tilts. When more air is blown into the balloons, it expands and the origami unfolds to reveal another lock position.

Following from the previous study, a series of balloons are created which combine the hinge movement with a rotational movement; the rotation origami balloon twists when inflated. To investigate the potential lock motions of each variant, the hinge and rotation balloons are combined in angles and stacks to provide alternative movement sequences. Below displays a matrix table, showing the hinge:rotation variables and their outputs.

Origami balloon matrix

Each origami balloon type provides an alternative folding sequence with either 1, 2 or 3 locking positions. These can then be manipulated as required, combining multiple balloons or re-dimensioning to suit their design intent.

One of the two principle origami balloon types is the hinge. When inflated, the balloon has the ability to tilt associated planes, creating a significant movement from a small inflation. The diagrams below show the digital simulation of the
movement, created in Grasshopper. Hinges can be combined with rotation origami balloons and other hinge balloons to create a sequence of tilting, rotational movements.

The second principle origami balloon types is the rotation. When inflated, the balloon has the ability to rotate, which can subsequently rotate any associated planes.

Rotation origami balloon

In order to create the grasshopper simulation, each origami balloon must be evaluated to extract each point of the shape. Once the points have been determined, they are allocated a series of values which determine the folding motion of the origami. The script must be programmed to prompt specific points to fold into one another.

Grasshopper hingepoints

Each origami model has a unique template which determines the angles of rotation and tilt. The templates are a combination of mountain and valley folds, each one carefully designed to ensure that when inflated, the balloon expands in the desired motion.

Origami templates

The origami system is then translated into a field array to study how the balloons can operate simultaneously.

1

To create the array below, a sequence of fins have been assigned to each balloon in over-lapping arrangement which can be used to parametrically open and close the panelised surface.

The next array acts similarly to a shutter system, displaying how a series of fins can be associated to one another to create a sequence of movements. The more inflated the balloon, the more vertically the associated fin will be, pulling each connecting fin towards it and thus retracting the series of panels.

Following from this, examples of the origami balloon field array mapped to a shape are studied, providing an insight as to how the array could be applied to an object. In the field map below, the panels are more open towards the top of the shape and are closed at the sides. In practice, this could be a result of the balloons inflating to further locking positions towards the top of the structure as a result of more exposure to sunlight /air flow which could increase the expansion of the origami balloon.

Origami balloon field mapped to shape

The below panelised field map displays the sequence of an interlocking array. The surface is more closed where the uninflated origami balloons are located. The interlocking sequence becomes more open once the origami balloons have inflated further, showing how the balloons can be manipulated to determine the transparency of a plane.

Origami balloon field mapped to surface

The origami balloon studies thus far have focused on individual balloons with separate associated end-effectors. To develop the scope of the origami balloons, a series of balloons connected by tubes has been constructed. Each origami balloon in the sequence shares the same air input system, and as a result develops a sequence of movements.

Physical origami balloon linkage model
Digital origami balloon linkage model

The creation of origami models lead to the study of paper as a material, and its position within the environment. Research into the paper manufacturing industry uncovered how masses of water and deforestation takes place as a result of paper manufacturing, with 14% of global deforestation solely for paper production. This prompted the investigation of recycled paper.

Paper industry statistics

The process I undertook to make the recycled paper required shredding old, disused paper found around the studio and recycling bins. The shredded paper is then mixed with water and blended to break down the fibers, converting the material into a pulp. The pulp is then laid onto a frame, the dimensions of which determine the sheet size. The pulp is removed from the frame, sponged and dried to create a new usable paper sheet.

Recycled paper making process
Paper is coated with wax to seal
Matrix of paper sheets, with varied recycled paper compositions and weights

Oil can be used to coat the sheet which increases the transparency of the paper. Once the oil is completely dried, the paper remains transparent. Image above shows the same two sheets of hand-made recycled paper, with the one on the right coated in oil.