3D Printing Electrical Impedance Tomography - Multi-electrode Impedance Measurements

BSc assignment

With the widespread adoption of 3D printing and especially Fused Filament Fabrication techniques, the need for the development of robust monitoring methods to ensure print consistency and product quality has arisen.
Currently, most (consumer grade) FFF 3D printers do not feature movement and or process sensing abilities, operating by purely following instructions without verification of their correct execution. Monitoring of the printer through its motion/extrusion system, printhead/bed/filament temperatures, printhead acceleration and vision algorithms have been proposed as possible solutions with varying success.
Our group is in the midst of developing a methodology that can directly measure the properties of the produced part as it is being printed. Through the use of Electrical Impedance Tomography (EIT) in combination with conductively doped polymers, an image of the produced part and inter-layer adhesion can be derived.

Given the complex geometries allowed by 3D printing, the location of the measurement electrodes has a great influence upon the ability to detect and locate defects with the impedance tomography technique. Measuring across printbed electrodes would allow for observation of warping and inter-layer adhesion problems, where nozzle to bed electrode measurements would allow for observation of the deposition process as well as bridging defects.

This BSc assignment will focus on characterizing the various possibilities for multiplexing the impedance measurement across a selection of electrodes. Key issues such as timing, switching speeds and crossover talk between electrodes should be addressed as well as the feasibility with commercially available equipment. The location and quantity of electrodes for an optimal measurement will also be addressed, given the large geometry dependence of electrical impedance measurements.