Strain Sensors Based On Cr Nanoparticle Arrays

The electronic properties in this metal nanoparticle arrays is different from the classic Ohmic transport mechanism. In a film based on closely spaced metallic nanoparticles, quantum transport is the dominant electronic conduction mechanism. In this transport mode, we demonstrate that the conductance of the nanoparticle arrays is dominated by the quantum transport between the closely spaced nanoparticles. The conductance of the nanoparticle based films has a direct bearing on the percolation morphology of the nanoparticle array. According to this feature, we can fabricate high sensitive strain sensors by depositing metal nanoparticles between silver interdigital electrodes coated on the substrate of flexible plastic material like polyethylene terephthalate.The main work of this paper is fabricating and studying the sensitivity coefficient of strain sensor.After the fabrication of strain sensor, we measure the change of the conductance correlating with the variation of the inter-particle spacing in the nanoparticle arrays and get the typical value of the gauge factor g=(△R/R)/ε (here ε means the applied strain and AR/R means the relative variation of the electrical resistance induced by the strain).In the experiment of tensile test, the results show that the gauge factor g has reached 6.1, the relationship between △R/R and ε is a linear relationship. In the experiment of 2-D bending test, the sensor can show the pressure change of several pa when under a high pressure which is close to 105pa. In the experiment of bending test, we find that the resistance response increases with the applied strain exponentially. The device can make proper response without crack even with an applied strain as high as 3%, with a maximum relative resistance change as large as 2500%. The dynamic range of the device is more than one order of magnitude larger than that of the semiconducting strain gauges, which is normally limited to a strain of around 0.3%. With small applied strains, ε～0-0.16%, g is a reasonable approximation. From this approximation, a gauge factor g=40 can be estimated for the device, which is one order of magnitude larger than the gauge factor g=2 of the metal foil gauge.This paper also discuss the effect of surface coverage of nanoparticles, showing that the less the coverage is, the more sensitive sensors we can get.The sensor elements show a high sensitivity, and can easy to be scaled down, which are feasible for MEMS and NEMS applications.