In a groundbreaking development that could pave the way for a new era in pressure sensor technology, researchers at the Indian Institute of Science Education and Research Bhopal have successfully crafted a new, flexible organic crystal that holds immense potential for use in highly sensitive pressure sensors.
The team, which collaborated with researchers from the University of Queensland and the Queensland University of Technology, developed a crystal structure that is able to bend and stretch without breaking under mechanical stress. This makes it an ideal component for the future development of pressure sensor technology.
The new crystal, 4-trifluoromethyl phenyl isothiocyanate (4CFNCS), is flexible enough to be bent, twisted and coiled. The team used sophisticated computational techniques and challenging experimental methods such as synchrotron microfocus X-ray diffraction measurements to understand the origin of flexibility in this new type of organic crystal. 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, which 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.
The team also successfully used 4CFNCS to fabricate highly sensitive pressure sensors, by combining it with an electrically conducting polymer, PEDOT: PSS. Piezo-resistive or pressure sensors are devices that respond to pressure or force applied to them by a change in their electrical resistance. The composite developed using 4CFNCS and PEDOT: PSS 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," said Prof. Deepak Chopra, Department of Chemistry, IISER Bhopal.
The team's findings have been published in the prestigious journal Small, in a paper co-authored by Prof. Deepak Chopra, Dr. Mitradip Bhattacharjee, and their research scholars Ms. Avantika Hasija and Mr. Lakhvir Singh from IISER Bhopal along with Dr. Amy J. Thompson, Dr. Jack K. Clegg, Dr. John. C. McMurtrie from The University of Queensland, Australia and Ms. Megha S. N and Ms. Kiran S. R. N. Mangalampalli from SRM Institute of Science and Technology, Kattankulathur, Chennai.
Flexible organic crystal piezo resistive materials such as the one developed by the team are attractive because they are sustainable and easy to work with. 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.