Scalable Alignment and Selective Deposition of Nanoparticles for Multifunctional Sensor Applications.

Here reported is the layer-by-layer-based advanced manufacturing that yields a simple, novel, and cost-effective technique for generating selective nanoparticle deposition and orientation in the form of well-controlled patterns. The surface roughness of the three-dimensionally printed patterns and the solid-liquid-air contact line, as well as the nanoparticle interactions in dipped suspensions, determine the carbon nanofiber (CNF) alignment, while the presence of triangular grooves supports the pinning of the meniscus, resulting in a configuration consisting of alternating CNF and polymer channels. The polymer/nanoparticle composites show 10 times lower resistance along with the particle alignment direction than the randomly distributed CNF networks and 6 orders of magnitude lower than that along the transverse direction. The unidirectional alignment of the CNF also demonstrates linear piezoresistivity behavior under small strain deformation along with high sensitivity and selectivity toward volatile organic compounds. The reported advanced manufacturing shows broad applications in microelectronics, energy transport, light composites, and multifunctional sensors.