Stimuli-Responsive Polymer-Nanoparticle Inks for Printed Sensor Arrays

Human machine interfaces rely on devices that connect humans to the virtual world, and robotics to the physical one. To provide robotic devices with real-time information about their environment, easy-to-manufacture, lightweight and customizable electronic sensors that can map physical stimuli such as temperature and pressure are required. Advances in both manufacturing techniques (such as 2D and 3D printing) and materials have enabled small, flexible, sensors to be rapidly fabricated on a variety of substrates. This presentation will focus on my research group’s efforts to engineer printable, nanomaterial-polymer composites that can sense physical stimuli including temperature, humidity, and pressure, and to integrate these materials into multi-layer devices – including arrays of flexible sensors – on thin, polyimide substrates. In the first part of the presentation, I will describe the formulation of printable polymer-nanoparticle composites tailored to selectively respond to specific physical stimuli. These include temperature-response piezoresistive poly(lactic acid)-reduced graphene oxide (PLA-rGO) composites, humidity responsive hydrogel-silver microflake composites, and piezoelectric polyvinylidene fluoride (PVDF)-nanomaterial composites. These materials are formulated for patterning using direct ink writing, in which a viscous, shear-thinning ink is dispensed through a pressurized syringe onto a moving substrate. The effect of processing parameters on the crystallinity and dispersion of the resulting composites will be described. In the second part of the presentation, I will describe the use of laser-micromachining to ablate vias in polyimide substrates, allowing multilayer arrays to fabricated by printing on either side of the substrate. Data is collected from these arrays using a multiplexer to interrogate each individual sensor in the array. These materials and devices are strong candidates for integration with functional, customizable e-skins.