Context
3D printed conductive polymers can be used for the creation of (embedded) sensors. Where e.g. capacitive sensing is primarily related to geometry changes, piezoresistive sensing is both affected by geometry and the material properties. It has been amply demonstrated that polymer host materials, like Thermoplastic PolyUrethane (TPU) or Poly Lactic Acid (PLA), two popular materials for Fused Filament Fabrication (FFF) 3D printing, doped with carbon black (soot particles of roughly 50 - 500 nm) can be succesfully used for 3D printing of flexible conductive structures. Straining these material will in general lead to a change in resistivity implying that they can be used for piezoresistive sensing.
Goals of the assignment
Despite the many experimental results, a proper description/model for the relatioin between the stress-strain state and the resistivity of these materials is not yet well established. The goal of this BSc assignment is to a) first develop a material model to predict sensitivity as a function of strain, b) to extend this model to predict the resistivity of 3D printed conductors where the traxels (i.e. the 3D printed lines) form meta-materials with anisotropic properties and c) the compare the models with experimental results to test their validity and predictive properties.
Embedding
The assignmet will be part of the work in the NIFTy (Nature Inspired Fabrication and Transduction) group dedicated to Additive Manufacturing of electronic, smart and soft robotic structures, lead by Gijs Krijnen. The assignment will be guided by a PhD for daily guidance and the student will have weekly meetings with the supervisor and the NIFTy group.