In-situ laser sintering for the fabrication of fully 3D printed electronics composed of elastomeric materials

In-situ laser sintering can be used to locally sinter conductive inks in an uninterrupted process, enabling the embedding of printed electronics within 3D printed structures. In this work we apply a laser sintering method to create highly conductive silver features (50–125 $\mu\Omega$ cm) on top of and embedded within thermosensitive polymers printed by fused deposition modelling (FDM). We exploit this method to locally sinter silver inks deposited by direct ink writing (DIW) without external processing. Furthermore, we perform this while thermally preserving the 3D printed thermoplastic polyurethane (TPU) substrate which has a low glass transition temperature. By analyzing the effect of the process for both small and large shapes of conductive features, we show the importance of the transmitted power and sintering time. Lastly, we apply the developed method to produce flexible conductors and sensors. These include pressure and bending sensors that could find their way into cost-effective and customized soft electronic devices.