Wednesday, 23 January 2019

A Supramolecular Nanofiber-Based Passive Memory Device for
Remembering Past Humidity

U. Mogera, M. Gedda, S. J. George and G. U. Kulkarni
ACS Appl. Mater. Interfaces, 9, 32065−32070 (2017)

Memorizing the magnitude of a physical parameter such as relative humidity in a consignment, may be useful while maintaining recommended condition over a period of time. Here we fabricate a humidity-responsive device that can memorize the humidity condition it had experienced while being unpowered. The device makes use of supramolecular nanofibers obtained from the self-assembly of donor–acceptor (D-A) molecules, coronene tetracarboxylate salt (CS) and dodecyl methyl viologen (DMV) respectively, from aqueous medium. The fibres tend to develop electrically induced disorder under constant voltage, leading to increased resistance with time. The conducting state can be regained via self-assembly by exposing the device to humidity in the absence of applied voltage, the extent of recovery depending on the magnitude of the humidity applied under no bias. This nature of the fibres has been exploited in reading the humidity memory state which interestingly, is independent of the lapsed time since the humidity exposure as well as the duration of exposure. The device finds use in applications requiring stringent condition monitoring.

Posted by Dr. Umesha Mogera