Fold It! Origami in Science and Its Applications

Helena Dodziuk

© H. Dodziuk

An Interface: Origami Applications

Currently, the most interesting discoveries and fascinating objects are being created on the peripheries of various fields. Biochemistry and biophysics, mathematical modeling applications in different fields, or nuclear radiation and magnetic resonance imaging in medicine illustrate this trend. One such lesser-known intermediary field that has recently witnessed spectacular achievements is the application of origami in modern science and technology. Inspired by the old Far-East art of origami, this approach is useful not only when you want to transport antennae or solar panels, telescopic masts, tanks, and so forth to space stations (and back to earth) by significantly reducing the size of the transported object¹ (Fig. 1). By making use of shape-memory materials², S. Felton³ built a self-assembling robot that folds itself starting from a flat sheet in four minutes and walks away from its starting point.

Among the numerous proposed applications of origami are flexible lithium-ion batteries, in which one can store more energy than in traditional batteries by taking advantage of the folding⁴; stents that unfold inside arteries⁵; automotive crash-absorbing structures⁶; or a microscope Foldscope folded from a piece of paper, equipped with lenses and simple electronics (and costing less than $1), which promises to bring about a revolution in diagnostics of diseases that are devastating the developing world⁷. The development is so exciting that origami-based engineering is seriously contemplated.

Fig. 1. Zhong You folding structures (©Zhong You)

For obvious reasons, the collaboration started between origami and mathematics with mathematicians analyzing the way folds could be performed and devising models to explain the folding process and novel folding patterns. Then, through use of these new algorithms and models, the patterns were optimized for specific purposes, which were then used by scientists and engineers for their structures and devices^{3,
8}. One of the most fruitful was a fold known previously but then rediscovered by Miura, Miura ori. We will present it later.

The Origin of Origami

The word “origami” is, of course, Japanese, in which ori means "folding" and kami stands for "paper". The technique most probably originated in China about 1400 years ago. In its classical form, it consists of bending a square piece of paper to create a spatial figure without cutting, gluing, or any additional adornment. Today, there are origami schools in which sheets of paper—not necessarily square—are cut or decorated.

One of the most popular Japanese origami patterns is the Japanese symbol of happiness and life: the crane (Fig. 2). The first book on this technique (or art form) published in 1797 described 49 methods of crane folding. You can make it by following instructions on Crane.

Fig. 2. Origami crane. © H. Dodziuk

There is a sad story associated with origami cranes (Fig. 2). Sadako Sasaki, who at the age of two was one of the few to survive the nuclear bombing of Hiroshima, fell ill with leukemia at 11 years old. Believing the Japanese legend, she hoped that if she made 1000 paper cranes she would recover. She managed to make only 644. Her friends finished the work and buried her with a thousand of cranes.

Origami Ideas in Folding and Self-Folding Structures^8a^,9

It should be stressed that today origami has been accepted by the scientific community as more than an artistic activity. There are international conferences devoted to this combination of science, technique, and art. The last of these took place last summer in Tokyo¹⁰. The first scientists interested in origami were mathematicians who analyzed folding patterns and developed programs that allowed one to obtain novel desirable three-dimensional objects from flat sheets^{3,
11}. It turned out that the folded structure exhibited interesting mechanical properties; these are presented in a fascinating way in a video Elastic structures by Itai Cohen, Cornell University, Ithaca, NY, USA. Zhong You¹, the inventor of several origami-inspired devices, and Felton and co-workers³ discussed general ideas leading to the manufacture of folded devices from flat sheets and the advantages of this method.

Folding patterns can be created by applying computational origami programs^{3, 11b}. Folding can produce complex shapes and is scalable to various sizes leading to structures with high strength-to-weight ratios^8b. There is a considerable accumulated knowledge on making use of the strength of folded structures. Moreover, the planarity of the starting materials can be easily exploited by numerous fabrication techniques (like photolithography) or by inclusion of system components (like batteries and lenses in the case of the microscope presented later) prior to the folding that can be executed automatically. An exciting area of self-folding has emerged on the basis of various methods. One of them, which makes use of shape-memory materials², has been applied to obtain the self-folding robot mentioned above and discussed below³.

Miura Folding

The fold presented in Fig. 3 was known to origami lovers for a long time but Koryo Miura¹² rediscovered it when studying the mathematical theory of elasticity. Its applications proposed by Miura started with the folding and unfolding of maps. Traditional map folding, so-called orthogonal folding, requires complicated finger movements and is inconvenient when executed in the open air under windy conditions or in the confined space of a car. The process is also disturbed by the instability of the folds, which leads to incorrect folding. Moreover, the stress associated with orthogonal folding results in tears where two folds intersect.

Fig. 3. Miura fold. (© H. Dodziuk)

The Miura folding of a map avoids these drawbacks: it easily folds and unfolds (you can watch it on Miura fold). There is only one, unavoidable disadvantage of Miura map folding: it is that the map cannot be folded partially.

The Miura fold was applied to solar panels for their transport to the experimental Japanese satellite N2, where they were unfolded upon arrival¹³. Its great advantage is that the folding and unfolding can be executed by robots. The Miura fold was also applied in flexible lithium-ion batteries⁴. Thanks to the folding, their storage capacity is typically larger than that of traditional batteries.

Stents

The best-known stents consist of a small mesh tube used to widen narrow or weak blood vessels. More generally, according to Wikipedia, “a stent is a mesh ‘tube’ inserted into a natural passage/conduit in the body to prevent or counteract a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow access for surgery”. Zhong You and co-workers applied the origami technique to build a stent that could be inserted in the folded flat form into a narrowed artery and then inflated and unfolded to support the artery and allow for an undisturbed blood flow⁵. Moreover, stents can be covered with drugs that will be released slowly after insertion.

Fig. 4. Stents developed in the Zhong You laboratory. (© Zhong You)

The unfolding process takes advantage of the Ni-rich TiNi shape-memory alloy². Such alloys were also used in an origami robot, which will be briefly discussed below.

Airbags

Designing airbags that are folded but then supportive after a crash is a typical technical application of origami. Robert J. Lang ^6a and Zhong You^6b worked on such a project. One of the origami-based algorithms developed by Lang has been used in German software simulating the deployment of an airbag. This, in turn, gave manufacturers the first geometrically correct way of airbag folding, which resulted in fewer airbag crash tests.

Foldscope: The Folded Microscope

Manu Prakash, Stanford University, CA, USA, and co-workers¹⁴ used the origami idea to make Foldscope, a general platform for manufacturing origami-based paper microscopes. The devices can operate as bright-field, dark-field, and fluorescence microscopes. They are assembled from an almost flat paper sheet and, although hard to believe, the parts necessary to build it, cost less than one US dollar.

Fig. 5. A folded operating microscope Foldscope (© Manu Prakash)

However, its technical parameters are impressive: 2,000X magnification with submicron resolution (800 nm), a weight less than 10 g, and small enough (70 x 20 x 2 mm³) to fit into one’s pocket. Moreover, Foldscope requires no external power and is very user-friendly. It is also a heavy-duty device. It was not damaged after being dropped from a three-story building or after being stepped on by a person.

Fig. 6 summarizes the costs of the printed polymer microoptics, paper apertures, polymer dye filters, printed condenser lenses, the printed LED, paper micro-flexures, and a watch battery used to assemble Foldscope. It also shows the unfolded device and its side view.

Fig. 6. Summary of the cost of the parts used to build Foldscope (top left), its schematic view from above (top right), and the side view of its operation (bottom). (© Manu Prakash)

As can be seen in Fig. 7, high-resolution images obtained by using a Foldscope enable visualization, and therefore identification, of several bacteria. As pointed out by Manu Prakash and his team, “Its minimalistic, scalable design is inherently application-specific instead of general-purpose gearing towards applications in global health, field-based citizen science, and science education”.

Fig. 7. Microscopic view of the human sickle cell and several bacteria: A) Plasmodium falciparum, B) Trypasonom cruzi, C) Giradia lamblia, D) Dirofilaria immitis, F) human sickle cell, G) Escheria coli and Bacillus. (©Manu Prakash)

At present, Prakash’s team is carrying out a large-scale test of their devices with the help of 10,000 volunteers. The very low cost of the microscope combined with its high resolution provides a diversity of imaging capabilities, and its ability to survive harsh field conditions guarantees it a wide range of applications in science and education, especially in developing countries.

Self-Building Robot

Another fascinating device inspired by the origami technique is the self-folding robot made by Felton et al.³. As mentioned above, the robot consists of an almost flat (with batteries as a nonplanar structural element) multilayered sheet and folds itself by making use of the shape-memory properties of one of its layers. It can also walk a few steps away from the place at which it unfolded. One can watch the full process on Self-assembling robot.

Conclusions

Origami is quite simply fascinating. Today some familiar drugs, for example, aspirin¹⁵, have found new uses through their application in the treatment of illnesses other than those for which they were developed. Similarly, today the ancient Japanese art of origami is being applied in science and technology. It is not possible to describe all of its applications. However, sensors inspired by origami¹⁶^,17,18, microfluidic devices¹⁹, electronic devices²⁰, transparent conducting films²¹ and tested by DARPA (American Defense Advanced Research Projects Agency) foldable plastic telescope lens developed using the origami principles are worth mentioning, too.