Laser Sintering of Aerosol Jet Printed Conductive Interconnects on Paper Substrate

Growing demand for wearable and disposable electronics leads to a need for cost effective and compact sensor designs and fabrication. Most of the devices are multi-layered and require a carrier substrate to hold the sensors. Paper substrates have gained attention since they have the potential to act as both the sensor and the substrate itself. Paper-based printed sensors have been demonstrated and shown functional. However, device fabrication on paper is challenging because of the surface roughness, bleeding, and incompatibility with high temperature sintering processes needed to achieve high conductivity. The conductivity of the interconnects is therefore usually relatively low and imposes performance limitations. Here we report, for the first time, highly conductive silver nano-particle interconnects printed on a paper substrate and sintered with a continuous wave laser. The printing process was identified and the laser sintering parameters were optimized to achieve a conductivity of approximately 67% of the bulk material. As an example of application, interdigitated electrodes were printed and laser sintered. The leakage current was monitored while aging at 50°C /85% RH conditions and exposing to water and artificial sweat.