Abstract: Provided is an ink for a 3D printing system having excellent pseudoplasticity. The ink for a 3D printing system includes: silk nanofibers; and a natural polymer and/or a synthetic polymer.

Abstract: Described herein is a flexible piezoresistive switch sensor responding only to a minimum threshold compression deformation force. The switch sensor comprises a non-porous housing that separates an external environment from an internal environment; one or more decoupled electrodes comprising or formed of a flexible conductor; a non conductive insulating spacer layer enforcing the one or more decoupled electrodes in bending or twisting forces, while allowing electrode coupling due to compression; a piezoresistive layer decoupled from the electrodes via the insulating spacer layer; and an elastomeric polymer layer comprising one or more buckling or spring elements configured to separate a minimum required compression force on the piezoresistive layer and the non-conductive insulating layer.