Laser synthesized gold nanoparticles for high sensitive strain gauges

Recently, the conduction properties of nanoparticle films have received great deal of attention due to their unique properties attributed to quantum tunneling effect. Quantum tunneling effect, highly dependent on quantum barrier height and width, is very attractive for sensor applications. Resistive strain gauges based on gold nanoparticle (Au-NP) films show high strain sensitivity. These strain gauges are applicable for miniature applications because of its size. In addition, this nanoparticle films could be also used for various applications such as pressure and vapor sensors. Clean surfaces of laser generated Au-NPs provide high tunneling decay constant. Therefore, these films are promising for high sensitive sensor applications. In our study, the Au-NPs were directly synthesized in deionized water by nanosecond laser ablation method. The clean surface, size and aggregate clusters of Au-NPs offer advantages for high sensitivity strain sensor. We prepared Au-NPs films on flexible PDMS substrate by using hands-on drop-cast method. To obtain high gauge factor, we also investigated the nanoparticle concentration on the thin films. Laser-generated AuNPs films demonstrated gauge factor of ∼300 for higher than 0.22% strain and ∼80 for the strain lower than 0.22%, which is favorably comparable to reported sensitivities for strain sensors based on Au-NPs. Mechanical characterizations for the prolonged working durations suggest long term stability of these strain sensors. We discuss several models describing conductance of Au-NP films in low and high strain regimes. To the best of our knowledge, the conduction of laser generated Au-NP films has not been studied up to date, and it is the first study that shows high strain sensitivity of these films. Au-NP films may be promising for sensor applications.