Butterfly flight inspires researchers to explore new ways to create force and electricity

It all has to do with a material called chitin.
Loukia Papadopoulos
A butterfly's flight.jpg
A butterfly's flight.


Scientists at the Singapore University of Technology and Design (SUTD) have managed to produce gripping force and electricity by taking inspiration from a butterfly’s first flight.

This is according to a press release by the institution published on Tuesday.

An exciting phenomenon

They described the phenomenon as follows:

“The wings of a butterfly are made of chitin, an organic polymer that is the main component of the shells of arthropods like crustaceans and other insects. As a butterfly emerges from its cocoon in the final stage of metamorphosis, it will slowly unfold its wings into their full grandeur. During the unfolding, the chitinous material becomes dehydrated while blood pumps through the veins of the butterfly, producing forces that reorganize the molecules of the material to provide the unique strength and stiffness necessary for flight. This natural combination of forces, movement of water, and molecular organization is the inspiration behind Associate Professor Javier G. Fernandez’s research.”

In their latest work, the research team explored the adaptability and molecular changes of chitinous materials in response to environmental changes.

“We’ve demonstrated that even after being extracted from natural sources, chitinous polymers retain their natural ability to link different forces, molecular organization, and water content to generate mechanical movement and produce electricity without the need for an external power source or control system,” said Assoc Prof Fernandez.

Chitinous from discarded shrimp shells

The researchers sourced chitinous polymers from discarded shrimp shells to create films that are about 130.5 micrometers thick. They then were able to observe that similar to the unfolding wings of butterflies, stretching the chitinous films reorganized the crystalline structure into a material that could autonomously relax and contract resulting in an ability to lift objects weighing over 4.5 kilograms.

The research team then assembled these new films in a mechanical hand that could be controlled through environmental changes and biochemical processes. The end result was a gripping hand with a force equivalent to 18 kilograms—more than half the average grip strength of an adult. 

In another demonstration, the team showed that the response of the material to humidity changes could be used to harvest energy from environmental changes and convert it into electricity.

“Chitin is used for many complex functions in nature, from making the wings of insects to forming the hard protective shells of molluscs, and has direct engineering application. Our ability to understand and use chitin in its native form is critical to enable new engineering applications and develop them within a paradigm of ecological integration and low energy,” said Fernandez.

The study was published in Advanced Materials Technologies.

Study abstract:

Passive actuation is the production of movement or deformation without external power sources or control systems. This phenomenon has been gaining significant attention in the engineering community due to its potential use in energy-efficient systems, in which part of the functionality is programmed in the material composition to reduce overall cost and complexity. Biological organisms, formed through millennia of evolution in a paradigm of limited resources and energy and at a multiscale equilibrium with their environment, have developed a myriad of outstanding materials and strategies for integrating complex functionalities into their multiscale structural design. In this study, the arthropod exoskeleton's chitinous composition and manufacturing strategies are used to reproduce its complex relations with external forces and water-driven molecular rearrangement and use them to produce electricity and actuate a mechanical hand. The proposed technology is unique in combining the generation of strong forces and the integration of the principles and materials of biological organisms, leading to significant advances in the design and performance of passive solutions integrated into biological systems for a wide range of applications, such as biorobotics, medical devices, and energy harvesting.