ETH Zurich

Two PhD positions in Biophysics and rheology of bacterial biofilms 100%, Zurich, fixed-term print Drucken The bioMatter Microfluidics Group of Dr Eleonora Secchi at ETH Zurich is seeking two PhD candidates. Our research focuses on uncovering the physicochemical mechanisms that control microbial surface colonisation and biofilm assembly, structure, and rheology. We use a broad spectrum of technologies in materials science, microbiology, and microfluidics, as well as advanced imaging techniques to address our questions. We are a highly interdisciplinary, international, and collaborative team of about 10 members, hosted within the chair of Prof. Roman Stocker in the Institute of Environmental Engineering. Project background The two PhD positions are part of a recently funded SNSF project aimed at systematically investigating nonlinear biofilm rheology, with emphasis on the role of extracellular DNA (eDNA). Biofilms are a ubiquitous form of microbial life with important implications in medicine, industry, and the environment. They are responsible for persistent infections, antibiotic resistance and biofouling, leading to economic costs of billions of dollars annually and thousands of deaths. Biofilms are microbial communities encased in a polymeric matrix that provides mechanical stability and protection from mechanical stresses through its viscoelastic properties. While the linear viscoelastic response under small deformations is well characterised and recognised as a virulence factor, the response to large deformations remains poorly understood. In particular, there is a lack of systematic investigation of the nonlinear regime, where externally applied loads can induce stress-hardening and stiffening of the biofilm matrix. Recent findings from our group suggest that eDNA may play a central role in the stress-hardening of biofilms. We hypothesise that this behaviour arises from the entropic elasticity of the eDNA network, a mechanism well described in polymer physics but largely unexplored in living biofilms. This could enable both short- and long-term adaptation to flow fluctuations. While initial experiments are consistent with this hypothesis, further investigation is required to validate the underlying molecular mechanisms and to determine whether stress-hardening is specific to streamers or constitutes a broader feature of biofilm mechanical adaptation across different morphologies. This project will test these hypotheses through a combination of structural, biochemical, and rheological analyses of the biofilms and mathematical modelling, with the potential to reveal fundamental principles of biofilm resilience. Job description Experimentally investigate nonlinear rheology and stress-hardening in bacterial biofilms with different morphologies using custom microfluidic and rheometry platforms. Quantify the role of eDNA and its interactions with biofilm matrix components using mutant libraries, enzymatic/antibody assays, and controlled physicochemical conditions; assess incorporation of exogenous DNA into biofilms and its impact on morphology and mechanics. Develop and apply advanced fluorescence/confocal imaging approaches to resolve biofilm network structure and eDNA conformation in situ. Contribute to the development of a numerical predictive model of biofilm mechanics. Collaborate within an interdisciplinary team and with external partners; communicate results through publications and presentations. The tasks include wet-lab experimentation, project management, numerical modeling and teaching duties. Position details: Start date: February 1st, 2026, or by agreement Fully funded PhD position (approximately 4 years). Final admission to the doctoral programme follows a successful Aptitude Colloquium at the end of year 1; contracts are extended annually. Profile The ideal candidate holds a Master-s degree in: physics, biophysics, materials science, microbiology or a related field with a strong interest in interdisciplinary research at the interface between soft-matter physics and microbiology Experience in experimental work such as microfluidics, rheology, microscopy, or culturing microbes and familiarity with data analysis and quantitative modelling is highly valued The candidate should be motivated to work both independently and collaboratively within an international research environment and to contribute actively to teaching activities Workplace Workplace We offer Training opportunities Perspectives for career development Support programmes (e.g. mentoring) and networks Your (team) culture and team composition Working environment and employment conditions Your commitment to diversity (e.g. flexible working hours, possibility for part-time work, home office) chevron_right Working, teaching and research at ETH Zurich We value diversity and sustainability In line with our values, ETH Zurich encourages an inclusive culture. We promote equality of opportunity, value diversity and nurture a working and learning environment in which the rights and dignity of all our staff and students are respected. Visit our Equal Opportunities and Diversity website to find out how we ensure a fair and open environment that allows everyone to grow and flourish. Sustainability is a core value for us - we are consistently working towards a climate-neutral future. Curious? So are we. We look forward to receiving your online application by November 30th, 2025 , including the following documents: Curriculum vitae Cover letter (including motivation, research interests and possible start date) Full transcript from undergraduate studies (both Bachelor and Masters) Copy of Master-s or Bachelor-s thesis (PDF) At least two reference letters Applications will be reviewed as they are received. Please note that we only accept applications submitted through our online application portal. Applications sent by email or post will not be considered. For questions regarding the position (but not for submitting applications), please contact Dr Eleonora Secchi (esecchi@ethz.ch). About ETH Zürich ETH Zurich is one of the world-s leading universities specialising in science and technology. We are renowned for our excellent education, cutting-edge fundamental research and direct transfer of new knowledge into society. Over 30,000 people from more than 120 countries find our university to be a place that promotes independent thinking and an environment that inspires excellence. Located in the heart of Europe, yet forging connections all over the world, we work together to develop solutions for the global challenges of today and tomorrow.

PhD Position: Synthetic surrogates to trace microbial transmission in healthcare settings 100%, Zurich, fixed-term print Drucken Hospital acquired infections are a major problem in medical care settings, resulting in prolonged hospital stays, increased treatment costs and in excess deaths. For a long time, HAI were deemed inevitable but nowadays, there is strong evidence that HAI are preventable by complying to hygienic standards. One crucial element to combat the endemic of healthcare-associated infections is being able to trace and track the transmission pathways of pathogens to develop effective interventions. There is a lack of rapid tools to understand and monitor the spread of pathogens. Building on our previous work on DNA tracing technologies, we aim to develop tools and procedures to model and monitor the spread of pathogens without directly employing and measuring pathogens. Project background The goal of this project is to continue the development of synthetic surrogates of common pathogens with comparable physicochemical properties, especially susceptibility towards alcohol disinfection, stability upon desiccation and the ability to be transferred from one surface to another by touch. The use of DNA as a reporter molecule shall allow the use of the ultra-sensitive detection method of quantitative Polymerase Chain Reaction (qPCR). This method of detection will enable us to not only monitor the spread, but to additionally perform validations of hygiene protocols and other means of preventive measures. We have set-up collaborations with major European hospitals to be able to test the synthetic surrogates developed in this project in real world scenarios. Job description Formulating novel pathogen surrogates Comparing the novel surrogate stability and disinfectant susceptibility with real pathogens Discussing surrogate application and testing scenarios with medical professionals Collaborating with medical professionals in exposure scenario testing Develop new understandings on how pathogens spread and act The tasks include wet-lab based experimentation, project management and teaching duties. Position details: Start date: Jan. 1st 2026 or by agreement Funding: Fully funded PhD position (ca. 4 years, final admission to Doctoral Program after successful Aptitude Colloquium after 1.5 years, annual contract extensions) Profile You meet the requirements for a doctoral program at ETH Zurich and have an excellent Master's or diploma in chemical engineering, chemistry, interdisciplinary sciences, biochemistry, biomedicine or a related field. Aside of hiring direct university graduates, we also encourage candidates with up to 3 years work experience in industry to apply. In any case, you already have significant experience working experimentally in a wet-lab, preferably in organic chemistry, biochemistry and/or nucleic acid technologies. You are highly motivated to learn and apply new product design and experimental techniques and collaborating with scientists from other fields (biochemistry, hygiene and medicine). The ability to work independently and excellent communication and writing skills in English complete your profile. Workplace Workplace We offer We offer a full-time position for the duration of your doctoral studies, starting upon agreement. We are providing a supportive environment that fosters professional and personal growth. You will join a dynamic, motivated and interdisciplinary team of researchers with expertise in chemistry, chemical engineering, biotechnology, product design and technology transfer, working collaboratively with research and industry partners. You will work in an inspiring, collaborative environment to address critical medical challenges. It includes opportunities to engage in group discussions and collaborative efforts in understanding how people from various backgrounds imagine the invisible world of pathogens. Our research group has an interdisciplinary, product design, technology transfer and entrepreneurial spirit. We have already commercialized many technologies and spun out several companies, in the medical, diagnostic and other industries. The PhD position provides access to state-of-the-art experimental opportunities enabling impactful research. The position supports the development of critical thinking, data analysis, problem-solving, and project management skills while contributing to the broader academic community through publications in peer reviewed journals. chevron_right Working, teaching and research at ETH Zurich We value diversity and sustainability In line with our values, ETH Zurich encourages an inclusive culture. We promote equality of opportunity, value diversity and nurture a working and learning environment in which the rights and dignity of all our staff and students are respected. Visit our Equal Opportunities and Diversity website to find out how we ensure a fair and open environment that allows everyone to grow and flourish. Sustainability is a core value for us - we are consistently working towards a climate-neutral future. Curious? So are we. We look forward to receiving your online application with the following documents: Curriculum Vitae, max. 2 pages Transcript of records Copy of Master or Bachelor Thesis (pdf) Contact details of min. 1 referee We exclusively accept applications submitted through our online application portal until November 30th 2025. We will not consider applications sent via email or postal services. We will get in touch with you before end of December 2025. Questions regarding the position should be addressed to Prof. Dr. Robert Grass rograss@ethz.ch (no applications, no application documents or inquiries of the application status; we may not respond to your e-mail). Pre-selection is carried out by the responsible recruiters and not by artificial intelligence taking into consideration the fit to the hard skills expertise required for the position. We encourage applications without the use of AI. For further information about the Functional Materials Group, please visit our website. About ETH Zürich ETH Zurich is one of the world-s leading universities specialising in science and technology. We are renowned for our excellent education, cutting-edge fundamental research and direct transfer of new knowledge into society. Over 30,000 people from more than 120 countries find our university to be a place that promotes independent thinking and an environment that inspires excellence. Located in the heart of Europe, yet forging connections all over the world, we work together to develop solutions for the global challenges of today and tomorrow.