Molecularly-capped nanoparticles have been explored for chemical and biological sensing in a number of significant way. A challenging area is the control of interparticle spatial properties of the nanoparticles in complex sensing environment. This poster describes the findings of a study of the electrical properties of self-assembled thin films of metal nanoparticles on interdigitated microelectrodes. The interparticle spatial properties of the thin film assemblies were engineered by alkyl molecules of different chain length. The electrical properties are systematically examined as a function of chain length, nanoparticle sizes, temperature, and relative humidity. The electrical conductivity is shown to depend on both chain length and particle sizes. The effects of temperature and humidity on conductivity were performed in an environmental chamber. The results have shown that the thin film conductivity is characteristic of thermally-activated semiconductors. A linear relationship between interparticle spacing and the activation energy is revealed for the first time. These findings have provided important insights into the design of nanostructured sensing materials for the construction of novel sensor arrays with high selectivity, sensitivity, and stability.