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Empa is the research institute for materials science and technology of the ETH Domain and conducts cutting-edge research for the benefit of industry and the well-being of society.

Empa’s Laboratory of Biomimetic Membranes and Textiles is offering a

PhD position titled: Electrohydrodynamics for drying of soft, heat-sensitive materials

Our laboratory. Empa’s Laboratory of Biomimetic Membranes and Textilesaims to develop materials and systems for the protection of the human body and its health. The products developed in collaboration with industry are used in the fields of occupational safety, sport, medical applications and health-tech.

. The principle behind electrohydrodynamic (EHD) drying is that airflow is generated by means of corona discharge, so-called ionic wind. This ionic wind enhances heat and mass transfer from any wet material that is placed in this airflow field. As electrohydrodynamic drying is a non-thermal technology, it is particularly attractive to dehydrate soft, heat-sensitive products, such as several foods. Compared to conventional convective drying, EHD drying has been reported to reduce drying time, reduce product shrinkage, increase rehydration capacity, improve (soften) texture, and preserve color and flavor better. It is also found to preserve better the nutritional content (vitamins). Several of the physical processes that occur in electrohydrodynamic drying are also relevant for electrospinning processes. This technology is used at our lab to spin micro- and nano-fibrous, functionalized membranes for tissue engineering and drug delivery.

.The first aim is to increase our insight in the EHD drying process and the electrospinning process via multiphysics modelling of the electrostatics, the ion flow, the resulting EHD-generated airflow and, finally, the material drying process. This mechanistic modeling approach should complement the current experimentally-based knowledge. The second aim of this project is to design, build and optimize an advanced, lab-scale experimental setup for electrohydrodynamic analysis of drying of soft materials. With this unique experimental setup, we aim to better quantify the contribution of the different drivers behind the drying process.

Your tasks

  • Develop a computational multiphysics model for electrohydrodynamics for drying of soft materials. This includes hygrothermal transport in the material during drying, evaporation of liquid water at the surface, convective exchange with the environment, electrostatics, ion flow and thermally-driven biochemical changes within the material during drying.
  • Use the simulation-based approach to better understand and steer electrohydrodynamic-driven processes, including EHD drying and electrospinning.
  • Designing, building and operating a lab-scale experimental setup for electrohydrodynamic analysis of drying of soft materials. Typical measurement methods include air speed measurements, thermal measurements, electrical power quantification

Your profile

. A project duration of 3 years is envisaged to carry out the above research tasks in the form of a PhD thesis. The project is supported by Empa under the supervision of Thijs Defraeye, but involves a joint affiliation with a Swiss federal or cantonal university. The candidate will perform his research at Empa in St. Gallen. Desired starting date is 1st of July 2019 or upon mutual agreement.

For further information about the position please contact Thijs Defraeye, thijs.defraeye@empa.ch and visit our websites https://www.empa.ch/web/det and www.empa.ch/web/s401 and Empa-Video.

We look forward to receiving your online application including a letter of motivation, CV, diplomas with transcripts and contact details of two referees. Please upload the requested documents through our webpage. Applications via email will not be considered.

Empa, Esther Zürcher, Human Resources, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland.