Master’s student

Interferometric Scattering Microscopy of Particles in Multilayered Nanofluidic Channels

Ref. 2022_013


Interferometric Scattering Microscopy (iSCAT) has emerged in the past two decades as a powerful imaging technique, allowing for label-free, high-speed and high-resolution imaging of biological nanoparticles, down to the size of single proteins. In its typical implementation, the particles are imaged at a water-glass interface. The light scattered by the nano-objects interferes with the light reflected at the glass-water interface and can be detected as a contrast. The contrast thereby depends critically on both amplitudes of scattered and reflected fields (Es and Er), as well as on the phase difference Δφ between them:

C = |Es|/|Er|* cos(Δφ)      (1)

In our group at IBM Research, we have developed a set-up called the Nanofluidic Confinement Apparatus (NCA), a tool allowing us to set nanometer-precise nanofluidic gaps between a cover glass and a substrate with a tilt accuracy of +/- 1 nm per 10 um lateral distance. This allows us to dynamically confine nanoparticles and use substrate materials and surface topographies that are challenging to access in a typical chip-based nanofluidic system. We have demonstrated controlled transport and precise sorting of nanoparticles, among others.

In this Master’s Thesis project, we would like to explore how multilayers coated on the confining walls of a nanofluidic slit can be used to optimize the contrast of freely diffusing, dielectric and biological particles. The choice of the multilayer system, in combination with the tunability of our nanofluidic gap, gives us several free parameters to optimize the quantities of equation (1). The effect of different layer structures on the scattered field distribution, the reflected light intensity and on the phase difference Δφ will be investigated. Comparing the results to an optical model will allow us to suggest optimal surface layers and predict the optical contrast of diffusing particles in a nanofluidic system.

The student will gain insights in micro-/nanofabrication in a state-of-the art cleanroom facility, learn to work on an optical set-up, perform experiments and process data (image processing, particle tracking, data analysis), as well as rationalize his results with different simulation techniques.

The academic supervision will be ensured by the Photonics Laboratory at ETH Zurich.


IBM is committed to diversity at the workplace. With us you will find an open, multicultural environment. Excellent flexible working arrangements enable all genders to strike the desired balance between their professional development and their personal lives.

How to apply

If you are interested in this position, please submit your application below.

For information on technical questions, please contact Philippe Nicollier, .