Semester Projects (can be adapted to Bachelor or Master level)
Microfabrication of electrodes for in situ TEM
Closed cell electron microscopy is rapidly gaining popularity as it enables to study many processes in its native liquid or gaseous environments. Incorporation of microelectrodes within the imaging region the cell allows us to study electrochemical processes, such as a function of catalyst in operation. Goal of this project is to optimize fabrication of microelectrodes within a MEMS device. Majority of the project will be conducted in a CMi cleanroom facility. Student will be introduced to photolithography and thin film deposition techniques.
Contact: Mr. Jan Vavra
Simulation of electric field distribution within micro-electrochemical systems
Electrochemical chips are used for in situ analysis of materials’s electrochemical progress within volatile solution for transmission electron microscopy studies. The confined environment may have critical impacts on the samples at micro- or nano-scale. As such, COMSOL simulation can be a practical way to clarify the configuration that induces environmental variations. The goal of this project is to compare the liquid environment within the liquid chamber sealed on the electrochemical chip with different configurations and under various experimental conditions through modelling. The student will correlate the simulated conditions to the obtained experimental observations.
Contact: Ms. Jing Hou
MEMs-based chips for in situ TEM applications
The aim of this project is to fabricate MEMS-based chip for in situ TEM applications such as biasing, heating, and electrochemistry. The student will be introduced to MEMS technologies such as photolithography, etching process, thin film deposition, etc. The process of the chip fabrication will take place in cleanroom at the Center of Micronanotechnology (CMi). The student is expected to understand the fundamentals of MEMS technologies and obtain hands-on experience with semiconductor processing. The MEMS processing skills obtained after this project are highly transferable especially in semiconductor industries. Previous hands-on experience in cleanroom is preferred for this project.
Contact: Mr. Tzu-Hsien Shen
ALD infiltration to enhance contrast in Nanotomography
FIB-SEM is a powerful tool to understand the 3D structure of materials at the nanoscale, since it can provide reliable information down to a voxel size of less than 10 nm; however, the 3D reconstruction of porous materials is often affected by artefacts due to the lacks of contrast between the materials and its pores. The aim of this project is to enhance the electron microscopy contrast of porous materials taking advantage of Atomic Layer Deposition (ALD) technique to fill the pores of the network with a contrasting medium. The student will find a recipe for Atomic Layer Deposition infiltration and use it to characterise porous materials having application in Fuel Cells and Li-ion battery fields. The transferable skills obtained in this project include experience in image processing.
Contact: Mr. Michele Bozzetti
Design and precision 3D printing of custom liquid cell enclosures
To better understand processes within a thin liquid layer inside a MEMS device for closed cell environmental electron microscopy, it is beneficial to correlate the TEM data with other analytical techniques such as optical microscopy or synchrotron x-ray absorption and fluorescence methods. However, each method has specific requirements in terms of sample mounting and positioning. Goal of this project is to design custom enclosures for these devices in Catia or Solidworks. The enclosures concentrate liquid channels and electrical contacts to an area of several mm2 and make a reliable interface to the MEMS device. Prototypes will be precision 3D printed and their function evaluated.
Contact: Mr. Jan Vavra
Modelling of the temperature distribution of the heating MEMS devices
Specialized silicon based MEMS devices are used for the in situ heating experiments in the transmission electron microscope. Heating of the device and the sample is achieved by passing current through molybdenum heating coil (~150 nm thick). Measurement of the temperature is done by measuring the resistance of the coil. Therefore, measurement is not done directly on the sample, but in the vicinity of it. The student will create models of two different MEMS device designs and use COMSOL for the calculations. Calculations will include heat loss terms due to thermal radiation, therefore temperature difference between heating coil and the sample position is expected to be temperature dependant. The main aim of the project is to assess the expected temperature difference between the measurement through the resistivity and the actual temperature on the sample.
Contact: Mr. Reinis Ignatans
Calculation of the oxygen K edge absorption spectra in the metal oxides
Metal oxide oxygen K edge spectrum gives information not only about the oxygen, but on he metal atom orbitals, which hybridize with the oxygen. Complete analysis of the absorption spectrum (electron energy loss spectrum), requires modelling. In simple cases (for example, alkali and alkali earth metal oxides) oxygen K absorption spectra is calculated relatively easy. On the other hand, transition metal oxides require more attention due to the highly correlated nature of the d-shell electrons. The student will do oxygen K edge calculations on the simple transition metal oxides and compare calculated spectra with the ones found in the literature and in the databases. Special attention will be paid to the Hubbard U value (corrective term for the correlated behaviour of the d-shell electrons).
Contact: Mr. Reinis Ignatans
Flow profile analysis
Flow profiles in a thin liquid layer inside an in-situ electrochemical cell for TEM will be investigated with the use of particle imaging velocimetry. Goal of this project is to analyze time series images of a tracer fluorescent nanoparticle and enable statistical processing of these variables, which would help understand the complex interplay of externally driven and electroosmotic flow in sub 200 nm water layers. The student will be introduced to particle imaging velocimetry and is expected to write a script using a programming language of his/her choice. Basic programming skills are required.
Contact: Mr. Jan Vavra
Ex situ electrochemical oxygen reduction reaction for identical location TEM studies of Pt/C electrocatalyst degradation
Proton Exchange Membrane Fuel Cells (PEMFCs) are one of the most promising technology for consumer use, but still face challenges regarding catalysts activity loss over time. Understanding the degradation mechanism of catalyst during operation is essential in order to design mitigation pathways and improve their long time efficiency and real-life applicability. This project aims at performing oxygen reduction reaction using a microfluidic electrochemical cell designed for in situ TEM in order to study catalytic activity variations over time. The student will optimise conditions for Pt/C nanocatalysts deposition on a microscale electrode, and will perform electrochemical characterisation of the system using cyclic voltammetry (CV). Ultimately, the cell could be brought to the TEM in order to study the degradation of a single particle over repeated cycles. The project involves gaining skills and knowledge on energy conversion systems characterisation and microscale electrochemistry.
Contact: Mr. Robin Girod