Materials Chemistry and Physics 276 (2022) 125371 Available online 23 October 2021 0254-0584/© 2021 Elsevier B.V. All rights reserved. Development of conductive thin flms as piezoresistive strain sensor Brijesh Prasad, Ph.D. a, b, * , Ibrahim M. Alarif, Ph.D. c , Fateh Singh Gill, Ph.D. d , Vikas Rathi, Ph. D. e , Varij Panwar, Ph.D. e a Department of Mechanical Engineering, Graphic Era Deemed to Be University, Bell Road, Clement Town, Dehradun, 248001, Uttarakhand, India b Institute of Advanced Materials, IAAM, Ulrika 59053, Sweden c Department of Mechanical & Industrial Engineering, College of Engineering, Majmaah University, P. O. Box: 66, Al-Majmaah, 11952, Saudi Arabia d Department of Allied Science (Physics), Graphic Era Deemed to Be University, Bell Road, Clement Town, Dehradun, 248001, Uttarakhand, India e Department of Electronics and Communication Engineering, Graphic Era Deemed to Be University, Bell Road, Clement Town, Dehradun, 248001, Uttarakhand, India HIGHLIGHTS • Development of cost-effective piezoresistive strain sensor. • Change in phase from non-polar to polar (Electrically active) to obtain high sensitivity. • The developed CNTFs showed improved fexibility and sensitivity. • High gauge factor and sensing ability compared to metal strain sensors. • CNTFs can also be applied for conducting substrate applications. A R T I C L E INFO Keywords: Conducting Nanocomposite Piezoresistive Strain sensor ABSTRACT Carbon nanocomposites are looked as the future smart materials for the applications of sensor transducers, ac- tuators and soft electronic devices. In the present work, we have developed conductive nanocomposite thin flms CNTFs using polyvinylidene fuoride (PVDF) dielectric polymer and vapour grown carbon nanofbers (VGCNF) conductive fller in varying 5, 10, 15 wt% concentration after optimization using solvent casting technique. VGCNF played a crucial role in developing conducting network as well as in enhancing the mechanical per- formance. The conducting behaviour was used for strain sensing and the mechanical behaviour helped in providing the fexibility for strain sensing application. The sample with 10 wt% of VGCNF showed best results for high conductivity 1.3 × 10 3 s/m and elongation of 5.8 × 10 3 mm. Moreover, the developed CNTFs showed a gauge factor around 2.88 which is higher to metal-based piezoresistive strain sensors and showed high fexibility. The developed thin flms can be looked for the application of human health and structural health monitoring for determining the change in electrical signals with respect to deformation. 1. Introduction CNTFs are the advance smart materials developed by infltrating the conducting fllers in the elastomer matrix [1]. The outstanding proper- ties of carbon-based conducting fllers like high surface area, high af- fnity to charges, high charge transportation, sensing make it a promising material with the piezoresistive materials. Moreover, it is well known that the combination of different compounds showing excellent electronic properties leads to new composite materials having great technological interest in recent years. The addition of a second phase can signifcantly improve the electronic properties of the resulting com- posite material [2,3]. PVDF is an important polymeric piezoelectric material widely used for transducer applications [4]. The high dielectric behaviour of PVDF showing multifunctional properties with nano- composites are very much in demand for biological, mechanical, elec- trical, soft robotic and smart energy applications [5–7]. PVDF carbon fllers in the form of piezoresistive strain sensor is one of the polymer transducer applications showing change in resistance in response to mechanical deformation. PVDF is highly recommended for the sensing application due to its * Corresponding author. Graphic Era Deemed to be University, Bell Road, Clement Town, Dehradun, India. E-mail addresses: prasadbrijesh10@gmail.com (B. Prasad), i.alarif@mu.edu.sa (I.M. Alarif), drfatehs@gmail.com (F.S. Gill), vikas.rth@gmail.com (V. Rathi), varijpanwarcertain@gmail.com (V. Panwar). Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys https://doi.org/10.1016/j.matchemphys.2021.125371 Received 26 August 2021; Received in revised form 16 October 2021; Accepted 20 October 2021