PhD defence by Anders Frem Wolstrup

Abstract

Imagine being able to 3D print electronic devices like sensors that track force, pressure, or strain, without needing expensive, specialized materials. This thesis investigates how a concept called “constriction resistance” can turn ordinary, low-conductivity 3D-printable plastics into practical sensors. Constriction resistance arises when electric current flows through a few tiny contact points in rough surfaces, adding extra resistance. By leveraging this effect, the sensor’s behavior depends primarily on the printed shape rather than on any special electrical qualities of the material itself. In other words, advanced sensing can be built from everyday composite plastics simply by controlling how the parts are printed.

Because the main problem with typical conductive filaments is that they aren’t especially conductive, these 3D-printed sensors are best suited for low-power setups. Yet, the project shows that well-designed structures, using multi-material printing, ironing to smooth surfaces, and precise control over how each line of plastic is laid down, can yield sensitive and reliable sensors. These devices plug straight into common electronics without a lot of extra circuitry, making them ideal for applications in everyday devices, from wearable monitors to robotic arms. Although the method faces challenges in large-scale manufacturing, for example, variations in print quality can affect results, the work offers solutions like drying the filament or carefully programming the print path to improve consistency. As 3D printing technology and materials evolve, this constriction-resistance approach may help bring custom, low-power sensor arrays to a wide range of fields, including wearable tech, robotics, and infrastructure monitoring.

Supervisors

• Main Supervisor: Associate Professor Gabriel Zsurzsan, DTU Electro, Denmark.
• Co-supervisor: Professor Michael A. E. Andersen, DTU Electro, Denmark.
• Co-supervisor: Professor Jon Spangenberg, DTU Construct, Denmark.

Assessment committee

• Professor Per Lynggaard, DTU Electro, Denmark (chair).
• Professor Ravinder Dahiya, Northeastern University, USA.
• Associate Professor Francisco Molina-Lopez, KU Leuven, Belgium.

Master of the Ceremony

• TBA