This paper reports the strain sensitivity of flexible, electrically conductive, and nanostructured cellulose which was prepared by modification of bacterial cellulose with double-walled carbon nanotubes (DWCNTs) and multiwalled carbon nanotubes (MWCNTs). The electrical conductivity depends on the modifying agent and its dispersion process. The conductivity of the samples obtained from bacterial cellulose (BNC) pellicles modified with DWCNT was in the range from 0.034？S·cm？1 to 0.39？S·cm？1, and for BNC pellicles modified with MWCNTs it was from 0.12？S·cm？1 to 1.6？S·cm？1. The strain-induced electromechanical response, resistance versus strain, was monitored during the application of tensile force in order to study the sensitivity of the modified nanocellulose. A maximum gauge factor of 252 was found from the highest conductive sample treated by MWCNT. It has been observed that the sensitivity of the sample depends on the conductivity of the modified cellulose. 1. Introduction Recently, sensors based on nanostructured material have attracted considerable attention due to their low power consumption, high sensitivity and selectivity, and prompt response [1, 2]. Conventional sensors are restricted in their application area by their rigidity and fragility. For this reason, development of sensor materials which are flexible and environmentally friendly has received a great deal of attention [3]. Comparing with ceramic and semiconducting materials, sensors which are based on organic nanostructured material have gained in significance due to their attractive properties [3]. It has been reported that such materials can be obtained by the introduction of nanoparticles with promising electrical and mechanical properties into a polymer matrix [4]. Among several nanostructures, carbon nanotubes (CNTs) have attracted a special interest because of their unique electronic, mechanical, and thermal properties which expanded the application field of CNT to nanoelectronics and biomedical devices [5]. Recently, the incorporation of CNT to polymers has been investigated to reinforce the mechanical properties of the polymers [4, 5]; it was shown that the elastic modulus and the ultimate strength of polymer composites increase even with the incorporation of small amounts of CNT. Cellulose, the most abundant natural polymer, is an inexhaustible raw material with fascinating structure and properties [6]. The properties of cellulose allow obtaining of environmentally friendly, biodegradable, and biocompatible products. Recently, research related to cellulose demonstrated its value
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