Chitin, a remarkable organic polymer prominent in the shells of arthropods and insects, has captured the attention of Associate Professor Javier G. Fernandez and his team. Inspired by the metamorphosis of butterflies and their wings, which showcase the adaptability and structural integrity of chitin, Fernandez has been investigating the potential of chitinous polymers as sustainable materials for engineering applications. Collaborating with researchers from the Singapore University of Technology and Design (SUTD), they have recently published a groundbreaking study in Advanced Materials Technologies that sheds light on the molecular changes and versatility of chitinous materials in response to environmental variations.
Contrary to common belief, chitinous polymers retain their extraordinary capabilities even after extraction from their natural sources. Fernandez and his team have demonstrated that these polymers can integrate various forces, molecular organization, and water content, enabling mechanical movement and even electricity generation without the need for external power sources or control systems. As the second most abundant organic polymer found in nature, chitin can be sourced easily from multiple organisms and even from urban waste, as proven by the SUTD research team. By extracting chitinous polymers from discarded shrimp shells, the researchers successfully produced films that measured approximately 130.5 micrometers in thickness.
To gain a deeper understanding of the behavior of chitinous films, the research team investigated the effects of external forces on their molecular organization, water content, and mechanical properties. Similar to the transformation seen in the unfolding wings of butterflies, stretching the chitinous films led to a reorganization of their crystalline structure. This reorganization resulted in tighter molecular packing and decreased water content, transforming the films from commodity plastics into materials resembling high-end and specialized plastics for engineering purposes. The most remarkable characteristic of these reorganized chitinous films was their ability to autonomously relax and contract in response to environmental changes, mimicking the adaptive behavior observed in certain insects. Thanks to this unique property, the films were able to vertically lift objects weighing over 4.5 kilograms, showcasing their potential for strength and resilience.
To illustrate the engineering applicability of these chitinous films, the research team integrated them into a mechanical hand. By manipulating the intermolecular water of the films through environmental changes and biochemical processes, the team generated sufficient force for the hand to exhibit a gripping motion. Impressively, the gripping force achieved was equivalent to 18 kilograms, surpassing half of the average grip strength of an adult. This biochemical means of generating force opens up possibilities for incorporating chitinous films into biological systems, making them suitable for biomedical applications such as artificial muscles and medical implants.
Moreover, the researchers demonstrated how the chitinous films’ response to changes in humidity could be harnessed to harvest energy from the environment and convert it into electricity. By attaching the films to a piezoelectric material, the mechanical motion induced by humidity changes was converted into electrical currents, capable of powering small electronics. This breakthrough highlights the multifaceted nature of chitinous polymers and their potential for energy harvesting applications.
Fernandez’s proof-of-concept study not only emphasizes the mechanical characteristics of chitin but also underlines its embedded functionalities. This research underscores the promise of chitin in various engineering and biomedical applications. As we strive to shift towards a more sustainable paradigm, Fernandez refers to chitin as the cornerstone of what he terms the biomaterial age. He firmly believes that comprehending and utilizing chitin in its natural form is instrumental in enabling new engineering applications and developing them within a framework of ecological integration and low energy consumption.
The study conducted by Associate Professor Javier G. Fernandez and the research team from the Singapore University of Technology and Design has unraveled the immense potential of chitinous polymers for sustainable engineering. Inspired by the natural adaptability and structural integrity of chitin, the researchers have demonstrated its ability to withstand external forces, retain molecular organization, and generate mechanical movement and electricity. With the possibility of sourcing chitin from various organisms and urban waste, its integration in engineering and biomedical applications opens up new doors for sustainable innovation. As we continue to explore the possibilities of chitin, its role in the biomaterial age becomes increasingly vital in driving ecological integration and minimizing energy consumption.