Integration of 3D printing with acoustic-assisted assembly of nanomaterials for tunable strain sensors

Abstract

This study reports a novel methodology for the development of tunable strain sensors by leveraging 3D printing for structural designs and nanomaterial assembly for functional layer coating. We utilized material extrusion (MEX) to print sensor substrates using composite ink of polydimethylsiloxane (PDMS) and silica nanoparticles. MEX allows us to create a non-uniform strain distribution of the sensor substrate by designing alternating wide and thin strips with different mechanical properties along the stretching direction. Then, we assembled nanometer-thick graphene flakes on the surface of the substrate using an acoustic-assisted dip-coating method to construct strain sensors. The graphene network on the narrow strips will experience large deformation leading to significantly increased resistance. By fixing the width of wide strips and tailoring the width ratio of the wide strip over narrow strips (r), the gauge factor can be controlled from 8.53 (r = 1:1) to 33.15 (r = 16:1). Also, by printing the narrow strips with softer PDMS, the sensitivity of the sensor can be further increased. The research pioneers the integration of 3D printing and nanomaterial assembly for strain sensors. More importantly, it paves the way for the generic design of flexible electronics and other hybrid systems of polymer and nanomaterials.