IISER Bhopal researchers develop organic crystalline materials for highly sensitive pressure sensors

NEW DELHI: The Indian Institute of Science Education and Research (IISER) Bhopal researchers have successfully developed a new, flexible organic crystal that shows great potential for use in highly sensitive pressure sensors. The understanding of the response of these crystals to mechanical deformation was done in collaboration with researchers from the University of Queensland and the Queensland University of Technology.

The device fabricated with this material has a high sensitivity to pressure, when compared to existing materials, making it a promising component for the future development of the technology of pressure sensors.

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There is a growing interest in the use of organic materials for electronic applications. The flexibility of organic materials makes them ideal for creating flexible electronic devices such as displays and sensors that can be bent or curved, providing a new level of design freedom. Organic crystals, in particular, have immense potential in the field of electronics, due to their few defects and minimal grain boundaries.

The researchers from IISER Bhopal and the University of Queensland have developed a new organic crystal – 4-trifluoromethyl phenyl isothiocyanate (4CFNCS) which is flexible enough to be bent, twisted, and coiled.

Speaking about the research, Professor Deepak Chopra, Department of Chemistry, IISER Bhopal, said, “We thoroughly analyzed 4CFNCS using sophisticated computational and challenging experimental techniques such as synchrotron microfocus X-ray diffraction measurements to understand as to why these are so flexible.”

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The in-depth analysis of the crystal structure showed that the way the atoms of this molecule are arranged in solids allows it to bend and stretch without breaking when subjected to mechanical stress. This helps to keep the crystal structure intact even under high pressure and impact. The slippage of molecules in multiple directions enables complex coiling motion in crystals.

Not only have the researchers uncovered the origin of flexibility in this new type of organic crystal, but they have also successfully used it to fabricate highly sensitive pressure sensors. The team combined 4CFNCS with an electrically conducting polymer, PEDOT: PSS, to make the piezo-resistive sensor.

“The composite developed using the researchers exhibited efficient piezo-resistive response, even at high-pressure ranges, resulting in at least 1.6-times improvement in sensitivity for medium pressure range, and at least 5 times in the high-pressure range across a wide range of pressures, over other known piezo-resistive materials," Professsor Deepak Chopra further added.

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Dr Mitradip Bhattacharjee, Assistant Professor, Electrical Engineering and Computer Science, IISER Bhopal, said, “These materials can be made without harmful chemicals or high-energy conditions, making them better for the environment. Apart from the applications of touch screens, such materials will be of great use in the design of flexible electronic devices, such as those used in healthcare, intelligent systems, wearable devices, and self-powered devices.”