Interdisziplinäres Zentrum für Materialwissenschaften

[Master Thesis Physik/Medizinphysik]
Micro-/Nanostructuring Controlled Porous Glasses
(PD. Dr. Alexander Sprafke, M.Sc. Davy Tesch)
Controlled Porous glasses (CPGs) are widely in pharmaceutical, chemical, and biological applications. Usage examples include filtering, transdermal drug-delivery systems, chromatographic separation, and many more. This is attributed to its morphological features that seem disordered but yet can be tuned in a large window of parameters.
Despite these applications, the optical potential of CPGs has been scarcely explored. Their high surface area and tunable disorder make them promising candidates for optical sensing. Their high adsorption capacity and ability to act as carriers for liquids allow for tuning of their optical response: adsorbed molecules modify the effective refractive index of the porous matrix, thereby altering its overall scattering characteristics. By structuring them on the micro- or nanoscale, in this project interaction with light shall be further engineered, enabling selective detection of analytes or enhancement of weak optical signals such as Raman scattering.

[Master Thesis / Bachelorarbeit]
Light transport properties of Controlled Porous Glasses
(PD. Dr. Alexander Sprafke, M.Sc. Davy Tesch)
Controlled Porous glasses (CPGs) are glasses with interconnected pore structures and their fabrication offers precise control of the mean-pore width, porosity and other quantities. This is of particular interest for mechanical and biological studies involving tensile strength, diffusion of liquids and drug delivery. However, the optical properties of CPGs are much less explored, particularly on micrometer-scale thicknesses. At this length-scale, optical effects become more pronounced due to the CPGs unique morphology. This thesis will focus on experimentally studying light transport in CPGs to shed light on its optical properties.
This thesis focuses on experimentally characterizing light transport in thin CPG membranes. Samples will be prepared via polishing or FIB-sectioning and analyzed using SEM and optical spectroscopy.

[Master Thesis Physik/Medizinphysik]
Artificial Neural Networks for predicting light scattering from disordered media
(Dr. Prerak Dhawan, PD. Dr. Alexander Sprafke)
Computational analysis of light scattering in disordered media (here: disordered arrays of identical particles) has long remained a challenging task due to the large degree of freedom in the spatial arrangement of particles. Researchers have often used approximate solutions for this problem, namely the Born’s first approximation. When the spatial correlations among the particles are not intuitively known, tailoring light scattering for a certain objective, like focusing of light or suppression of reflection, can be cumbersome since typical approaches involve either tuning the individual particle properties or tuning their spatial arrangement but rarely a combination of both simultaneously. Simultaneous optimization of both is typically done for periodic arrangements but rarely for a disordered arrangement.
The thesis involves training an artificial neural network (ANN) to predict the optical response of individual scatterers with varying parameters. After validating the ANN against known Mie solutions, it will be applied to optimize complex disordered arrangements for targeted scattering properties.

[Bachelorarbeit Physik/Medizinphysik]
Inverse design of disordered media for tailored light scattering
(Dr. Prerak Dhawan, PD. Dr. Alexander Sprafke)
The thesis involves computational studies of disordered media. The overall system consists of identical particles spatially arranged in a disordered manner. An existing in-house code — currently limited to spatial optimization — shall be extended by enabling simultaneous optimization of the particle’s physical properties for a defined optical objective, such as light-localization or anti-reflection. For simplicity, the approach here would use spheres as the scattering particles since light scattering from a single isolated sphere is analytically described byMie Theory.

[Orientierungspraktikum Physik-Master - IZM]
Simulated Annealing for 3D Microstructures
(PD. Dr. Alexander Sprafke)
This internship focuses on generating porous microstructures via simulated annealing based on defined statistical properties. The code will be implemented in Python and benchmarked against reference structures generated from differential equation models. Candidates with experience in Python Programming, Optimization methods and mathematical modelling background are encouraged to apply.