Ultrasensitive strain sensor based on graphite coated fibrous frameworks for security applications

The increasing demands of low cost, flexible, foldable and disposable electronic devices have directed the attentions of researchers towards applications of paper substrates. Here, we report the fabrication of strain sensor based on graphite-on-paper strategy. Graphite coating is applied on cellulose paper by direct drawing method. SEM and EDS analyses of the graphite electrodes are performed which respectively inform about the morphological features and elemental composition of the samples. Moreover, XRD, FTIR spectroscopy and UV-visible spectroscopy of the graphite electrodes are performed to investigate their structural and optical features. A device is fabricated using the graphite electrode which acts as strain sensor. The sensor responds to applied bending strain by showing changes in its relative resistance. The response of sensor towards applied strain is linear with linearity as 0.997. The sensor responds differently for applied inward and outward bending strains. An exceptional sensitivity of 122,701 is recorded for outward strain and 4,021 for inward bending strain. The response time of the sensor is measured as 0.59 s, while that of recovery time as 0.69 s. The sensor is applied on a door at its axis of motion for which it responds when the door is opened or closed. The results show that the demonstrated sensor could be worthful for advanced security applications.