Self-healing crystals for sensors, implantable biomedical devices
doi:10.1038/nindia.2021.103 Published online 21 July 2021
Materials scientists in Kolkata have prepared organic crystals that, when fractured, could recombine in a fraction of a second with precision1.
The crystals, they found, could autonomously self-heal without the need of external stimuli such as heat, light or solvent.
The researchers, from the Kolkata-based Indian Institute of Science Education and Research (IISER), said the crystals could potentially be used for fabricating organic electronic devices such as transducers, sensors, energy harvesters and even implantable biomedical devices.
The IISER scientists, collaborating with peers from the Indian Institute of Technology in Kharagpur, synthesised crystals of tetramethyl bipyrazole using methanol solution at ambient conditions. The team, led by C. Malla Reddy and Nirmalya Ghosh, then subjected single crystals to a bending test that generated fractures, giving rise to linear cracks in the crystals.
On withdrawing the force, the two fractured pieces self-propelled and rejoined in the blink of an eye, aided by a strong attractive force created by the opposite charges on the two broken ends.
A single crystal could undergo multiple cycles of crack generation and self-healing. In contrast to other self-healing materials, the fractured pieces in this crystal could also recombine even when physically separated, within a certain threshold distance.
The crystals self-healed perfectly, showing no sign of cracks, even when examined using sophisticated imaging techniques.
Insights from this research might be useful in shedding light on the self-healing processes of bones, muscles and collagen, said lead author Surojit Bhunia.
1. Bhunia, S. et al. Autonomous self-repair in piezoelectric molecular crystals. Science. 373, 321-327 (2021) Doi: 10.1126/science.abg3886