I was born and raised in Geneva, Switzerland, where I attended school until the end of collège (high school) in 2013. I then pursued an undergraduate Master's degree in Chemistry at the University of Nottingham. During my third of four years I spent an integrated year at the University of Hong Kong, before returning to the UK for my final year. In 2017 I started a DPhil (PhD) in Physical and Theoretical Chemistry at the University of Oxford. I graduated in 2023 and started post-doctoral research at Empa in St. Gallen, Switzerland.
I am specialised in surface force measurements, and more particularly in the surface force apparatus (also known as the surface force balance). My current work pertains to understanding near-surface forces on thin plasma polymer films.
EDUCATION
DPhil Physical and Theoretical Chemistry, University of Oxford, 2017-2023
Undergraduate MSci Chemistry, University of Nottingham, 2013-2017
Maturité cantonale, Collège Jean Calvin, 2009-2013
RESEARCH, TEACHING, or OTHER INTERESTS
Physical and Theoretical Chemistry, Surfaces, Coatings and Films, Materials Chemistry
5
Scopus Publications
45
Scholar Citations
3
Scholar h-index
2
Scholar i10-index
Scopus Publications
Potential and Challenges to Replace PFAS Coatings Considering Safe and Sustainable by Design Aspects: Review and Perspectives Dirk Hegemann, Astrid Southam, Manfred Heuberger, Paula Navascués Plasma Processes and Polymers, 2026 Per‐ and polyfluoroalkyl substances (PFAS) are widely used due to their unique properties combining liquid repellency with low friction and high thermal, mechanical and chemical stability. PFAS coatings, however, contribute to the release of long‐lasting chemicals, components of which break down very slowly over time. They are thus increasingly detected as environmental pollutants, and some are linked to negative effects on human health. Therefore, alternative coating materials and technologies are required, meeting PFAS properties for specific applications. Most of all, plasma technology offers a promising and green way to deposit ultrathin, fluorine‐free coatings firmly bond to material surfaces with adjusted chemical and nanostructural properties, while considering safety and sustainability of the entire lifecycle of the used materials.
Hydrophilic nano-porous model surfaces suitable for direct force measurements Michał Góra, Paula Navascués, Mohammad Alinezhadfar, Astrid Southam, Dirk Hegemann, Manfred Heuberger Applied Surface Science, 2025 • Hydrophilic PPFs exhibit high stability under different hydration conditions. • Surface forces of PPFs are analyzed using direct measurement techniques. • DPE-PPFs show expected force behavior in water and KNO3 of varying concentrations. • NPC-PPFs show complex repulsive force in liquids. • DPE-PPFs serve as a model system for direct force measurements. Molecular-level understanding of liquid–solid interfaces is key to the development of many physical, biological and chemical systems. In this context, functional plasma polymer films (PPFs) offer tunable surfaces ranging from hydrophilic to hydrophobic behavior. In this study, smooth hydrophilic PPFs with average surface roughness below 0.3 nm were fabricated from hexamethyldisiloxane (HMDSO) precursor by varying the substrate-plasma separation. The reference method consisted of direct plasma exposure (DPE) of mica and silicon substrates, while an alternative near-plasma chemistry (NPC) approach allowed film formation at a controlled distance, filtering out high-energy ions. Secondary ion mass spectroscopy revealed chemical and structural differences between the PPFs. Despite these, both films exhibited similar negative zeta potential in aqueous solution at neutral pH. The interfacial interactions at the PPF-liquid interface were accessed at different length scales using atomic force microscopy, colloidal probe microscopy, and the extended surface force apparatus. Both deposited films exhibited a degree of porosity and exceptionally low adhesion in water. DPE-PPF interactions were consistent with electrostatic double-layer theory, supporting its suitability as a model system for fundamental surface force studies. In contrast, NPC-PPF surfaces exhibited additional repulsive forces at 20 ± 10 nm in water, suggesting an additional mechanism beyond ordinary double-layer repulsion.
Integrated accuracy enhancement for the Fabry-Pérot interferometer: The multi-parameter approach series (MPAS) Michał Góra, Astrid Southam, Urs Schütz, Peng Zhang, Manfred Heuberger Review of Scientific Instruments, 2025 Fabry–Pérot white light interferometry is at the heart of the surface force apparatus (SFA). One of the applications of SFA is the measurement of properties of sub-nanometer-confined fluids. For the determination of the properties of a confined fluid, the absolute accuracy of SFA is directly linked to the accuracy of the parameters describing the optical layers of the interferometer, particularly the micrometer thick mica spacer layers. During the measurement of nano-confined films, most of the optical path occurs within these mica spacer layers, which are thus identified as the major accuracy-limiting factor. This work describes an integrated accuracy enhancement method, the so-called multi-parameter approach series (MPAS), which is especially designed to determine the mica thickness and its dispersive refractive index in situ at enhanced accuracy, without the use of the conventional mica–mica contact calibration. We show how the proposed procedure increases the absolute instrumental accuracy by increasing spectral correlation. The proposed MPAS algorithm provides a significant accuracy enhancement and concurrently reveals the need to assess the elasto- and opto-mechanical properties of mica for any further accuracy improvements.
The surface force balance: direct measurement of interactions in fluids and soft matter Hannah J Hayler, Timothy S Groves, Aurora Guerrini, Astrid Southam, Weichao Zheng, Susan Perkin Reports on Progress in Physics, 2024 Over the last half-century, direct measurements of surface forces have been instrumental in the exploration of a multitude of phenomena in liquid, soft, and biological matter. Measurements of van der Waals interactions, electrostatic interactions, hydrophobic interactions, structural forces, depletion forces, and many other effects have checked and challenged theoretical predictions and motivated new models and understanding. The gold-standard instrument for these measurements is the surface force balance (SFB), or surface forces apparatus, where interferometry is used to detect the interaction force and distance between two atomically smooth planes, with 0.1 nm resolution, over separations from about 1 µm down to contact. The measured interaction force vs. distance gives access to the free energy of interaction across the fluid film; a fundamental quantity whose general form and subtle features reveal the underlying molecular and surface interactions and their variation. Motivated by new challenges in emerging fields of research, such as energy storage, biomaterials, non-equilibrium and driven systems, innovations to the apparatus are now clearing the way for new discoveries. It is now possible to measure interaction forces (and free energies) with control of electric field, surface potential, surface chemistry; to measure time-dependent effects; and to determine structure in situ. Here, we provide an overview the operating principles and capabilities of the SFB with particular focus on the recent developments and future possibilities of this remarkable technique.
A 3-mirror surface force balance for the investigation of fluids confined to nanoscale films between two ultra-smooth polarizable electrodes C. D. van Engers, M. Balabajew, A. Southam, S. Perkin Review of Scientific Instruments, 2018 We present a new technique, based on the Surface Force Balance (SFB), for the direct measurement of surface forces between two ultra-smooth and polarizable gold electrode surfaces across thin fluid films. Combining the direct interferometric measurement of surface separation and contact geometry with smooth electrode surfaces has proved challenging in the past, and for this reason, previous measurements with the SFB typically involved two insulating mica surfaces, or one mica surface and one electrode surface, or an alternative less direct measure of the surface separation. Here, we demonstrate that a 3-mirror interferometer can overcome these difficulties: the setup involves two ultra-smooth electrode/mirror surfaces between which the fluid is confined and a third mirror to allow for interferometric detection of the liquid thickness with nanometer resolution and at thicknesses much smaller than the diffraction limit of the light. We conclude with a proof-of-concept measurement across dry nitrogen gas. The technique should prove useful for studying the properties of fluids confined at the nanoscale inside a slit-pore of controlled electrical potential or subject to applied electric fields.
RECENT SCHOLAR PUBLICATIONS
Potential and Challenges to Replace PFAS Coatings Considering Safe and Sustainable by Design Aspects: Review and Perspectives D Hegemann, A Southam, M Heuberger, P Navascués Plasma Processes and Polymers 23 (1), e70125 , 2026 2026.0 Citations: 4
Hydrophilic nano-porous model surfaces suitable for direct force measurements M Góra, P Navascués, M Alinezhadfar, A Southam, D Hegemann, ... Applied Surface Science 708, 163776 , 2025 2025.0 Citations: 1
Integrated accuracy enhancement for the Fabry–Pérot interferometer: The multi-parameter approach series (MPAS) M Góra, A Southam, U Schütz, P Zhang, M Heuberger Review of Scientific Instruments 96 (8) , 2025 2025.0
The surface force balance: direct measurement of interactions in fluids and soft matter HJ Hayler, TS Groves, A Guerrini, A Southam, W Zheng, S Perkin Reports on Progress in Physics 87 (4), 046601 , 2024 2024.0 Citations: 18
The behaviour and charging dynamics of concentrated electrolytes in confinement under potential control A Southam University of Oxford , 2022 2022.0
A 3-mirror surface force balance for the investigation of fluids confined to nanoscale films between two ultra-smooth polarizable electrodes CD van Engers, M Balabajew, A Southam, S Perkin Review of Scientific Instruments 89 (12) , 2018 2018.0 Citations: 21
Absence of Long-range Hydrophobic Surface Forces on Stable Plasma Polymer Films A Southam, M Gora, P Navascués, U Schütz, P Rupper, D Hegemann, ... Available at SSRN 5472182 , 0 Citations: 1
MOST CITED SCHOLAR PUBLICATIONS
A 3-mirror surface force balance for the investigation of fluids confined to nanoscale films between two ultra-smooth polarizable electrodes CD van Engers, M Balabajew, A Southam, S Perkin Review of Scientific Instruments 89 (12) , 2018 2018.0 Citations: 21
The surface force balance: direct measurement of interactions in fluids and soft matter HJ Hayler, TS Groves, A Guerrini, A Southam, W Zheng, S Perkin Reports on Progress in Physics 87 (4), 046601 , 2024 2024.0 Citations: 18
Potential and Challenges to Replace PFAS Coatings Considering Safe and Sustainable by Design Aspects: Review and Perspectives D Hegemann, A Southam, M Heuberger, P Navascués Plasma Processes and Polymers 23 (1), e70125 , 2026 2026.0 Citations: 4
Hydrophilic nano-porous model surfaces suitable for direct force measurements M Góra, P Navascués, M Alinezhadfar, A Southam, D Hegemann, ... Applied Surface Science 708, 163776 , 2025 2025.0 Citations: 1
Absence of Long-range Hydrophobic Surface Forces on Stable Plasma Polymer Films A Southam, M Gora, P Navascués, U Schütz, P Rupper, D Hegemann, ... Available at SSRN 5472182 , 0 Citations: 1
Integrated accuracy enhancement for the Fabry–Pérot interferometer: The multi-parameter approach series (MPAS) M Góra, A Southam, U Schütz, P Zhang, M Heuberger Review of Scientific Instruments 96 (8) , 2025 2025.0
The behaviour and charging dynamics of concentrated electrolytes in confinement under potential control A Southam University of Oxford , 2022 2022.0
