Fabrication of 1D particle structures outside a liquid environment using electric and capillary interactions: From fundamentals to applications

Assembling microparticles into one-dimensional (1D) particle structures formed outside a liquid environment is challenging. This greatly hinders possible applications of such structures and the development of new materials. Herein, we demonstrate a simple, efficient, and easy-to-implement method for fabricating one particle–thick chain-like structures. Electrically conductive particles, initially dispersed in a nonpolar and weakly conductive liquid, are pulled out of the liquid using an electric field supported by capillary action. We study in detail how capillary and electric interactions, viscosity and ionic conductivity of the dispersing phase, particle shape, size and density, and pulling rate affect the general performance of our method. Our experimental results reveal that different types of microparticles can be assembled within seconds to form long chains. We found that capillary forces help aligning particles and creating single particle–resolution structures. The results show that dispersing liquids with large viscosity and low ionic conductivity are preferred as they reduce the negative effect of ionic screening. In the second part of our research, we investigate the physical properties of the produced beaded structures that we deem intriguing for both fundamental and applied research. We finally demonstrate that 1D particle structures can be used to design electrically conductive micropaths.