Indian scientists make breakthrough discovery of material that repairs itself

Scientists have developed piezoelectric molecular crystals that repair their own mechanical damage without the need for any external intervention, the Department of Science and Technology (DST) said on Saturday.

Piezoelectric crystals are a class of materials that generate electricity when it undergoes a mechanical impact.

Devices that are used daily often break down due to mechanical damage, forcing users either to repair or replace them. This decreases the life of the equipment and increases maintenance costs. In many cases, like in a spacecraft, human intervention for restoration is not possible.

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"Keeping such necessities in mind, researchers from the Indian Institute of Science Education and Research (IISER) Kolkata, in collaboration with IIT Kharagpur, have developed piezoelectric molecular crystals that repair themselves from mechanical damages without need for any external intervention," the DST said in a statement.

Called bipyrazole organic crystals, the piezoelectric molecules developed by the scientists recombine following mechanical fracture without any external intervention, autonomously self-healing in milliseconds with crystallographic precision, it said.

In these molecular solids, due to the unique property of generating electrical charges on mechanical impact, the broken pieces acquire electrical charges at the crack junction, leading to attraction by damaged parts and precise autonomous repair.

This research, supported by the DST through its Swarnajayanti Fellowship to CM Reddy and Science and Engineering Research Board (SERB) grants, has been published in the journal 'Science' recently.

This methodology was initially developed by the IISER Kolkata team led by professor C M Reddy, a recipient of Swarnajayanti fellowship (2015), professor Nirmalya Ghosh of IISER Kolkata, a laureate of the Society of Photo-Optical Instrumentation Engineers (SPIE) G.G. Stokes Award in Optical polarisation 2021, used a custom-designed state-of-the-art polarisation microscopic system to probe and quantify the perfection of the piezoelectric organic crystals, the statement said.

These materials with perfect internal arrangement of molecules or ions are called 'crystals' which are abundant in nature.

In the IIT Kharagpur's team, professor Bhanu Bhusan Khatua and Sumanta Karan studied the performance of the new materials for fabricating mechanical energy harvesting devices, it added.

The material may find application in high-end micro-chips, high precision mechanical sensors, actuators, micro-robotics. Further research into such materials may eventually lead to the development of smart gadgets that self-repair cracks or scratches.