Implementation of Multifrequency AFM for Open Science
Material engineering requires knowledge of the structure at the nanometric scale. Multifrequency Atomic Force Microscopy is a technique which offers the ability to get simultaneously topography, nanomechanical, electrical (and more) properties at high rates with high sensitivity. In this mode, a lock-in amplifier is used to excite the AFM cantilever at, at least, its two first resonance frequencies and to detect changes in the cantilever oscillations. In the scope of our open-hardware project, you would implement this AFM mode in our existing controller.
In this project, you will:
- understand how a lock-in works
- learn how to program a FPGA with Labview
- apply signal processing algorithms
- test the controller on polymer/biological samples.
Required: that you like programming
Contacts: Charlène Brillard, Georg Fantner
References D. Forchheimer, R. Forchheimer, D.B. Havilland, Improving image contrast and material discrimination with nonlinear response in bimodal atomic force microscopy, Nature Communications (2015), 6, 627  C.A. Amo, A.P. Perrino, A.F. Payam, R. Garcia, Mapping Elastic Properties of Heterogeneous Materials in Liquid with Angstrom-Scale Resolution, ACS nano (2017), 11 (9), 8650  A.P. Nievergelt, J.D. Adams, P.D. Odermatt, G.E. Fantner, High-frequency multimodal atomic force microscopy, Beilstein Journal of Nanotechnology (2014), 5, 2459-2467
Design and fabrication of a quadrature interferometric detection for video rate material atomic force microscopy on ultra-small cantilevers
Atomic force microscopy relies heavily on the calibration of the used cantilever probes. Traditionally the cantilever motions are detected by optical beam deflection. Using an interferometric detection scheme the cantilever motion is directly compared to the wavelength of light, enabling an extremely low noise detection at a bandwidth of multiple megahertz. Additionally, the spot can be made extremely small allowing for the readout of arbitrary MEMS and NEMS cantilevers. Using this, highly accurate nanoscale mechanical property measurements are enabled.
In this project you will:
- Learn about state of the art optical systems and design of optics assemblies.
- Gain experience in designing and manufacturing mechanical parts using computer aided design.
- Get introduced to modern high-frequency atomic force microscopy techniques for mechanical characterization at the nanoscale
Contacts: Santiago Andany, Georg Fantner
Bacteria analysis with atomic force microscopy
Master or Semester project
Using a developed microfluidic device for the immobilization of bacteria, the goal will be to analyze rod-shaped bacteria under the influence of different environmental conditions. In particular, by mimicking conditions in the gastrointestinal tract, bacteria (e.g. Escherichia coli and Bacillus subtilis) will be exposed to specific antibiotics. With the atomic force microscope (AFM) we will observe the changes on the surface of bacteria (and mechanical properties if master project). The experiment setup consists of an atomic force microscope with an inverted fluorescence microscope. The final goal is to determine whether there are and how much in particular, the conditions in the gastrointestinal tract influence the bacterial susceptibility to antibiotics (e.g. antimicrobial peptides).
- Basic knowledge in microbiology
In this project you will:
- Gain experience with AFM imaging on biological samples
- Use a microfluidic system together with a fluorescence microscope and AFM
- Use the obtained data for advanced analysis of bacteria under specific conditions
Georg Fantner, Mélanie Hannebelle
Microfluidic chip for selective delivery of bacterial cells
Design and implementation of a microfluidic device that sorts and delivers bacterial cells on demand. For the design, standard cleanroom fabrication technology will be used. The devices are made on silicon wafers using photolithography and dry etching. The final device will be out of soft polymer (e.g. PDMS). Similar devices have already been fabricated ; the goal will be to implement this into an already existing microfluidic system. You will be in charge of the design and fabrication of the microfluidic chip. After the fabrication, you will use polymer beads and yeast cells for the proof of principle of the cell sorting architecture of the microfluidic chip. The final goal will be to sort and selectively deliver rod-shaped bacteria on a microfluidic chip assembly for atomic force analysis.
- Basic knowledge in cleanroom fabrication
- Basic knowledge in CAD design
In this project you will:
- Design a microfluidic chip (with e.g. CleWin)
- Fabricate the microfluidic chip using standard cleanroom fabrication techniques
- Design the interface to the microfluidic chip with CAD software (e.g. Solidworks)
- Test the fabricated microfluidic chip setup with biological samples
 Monolithic microfabricated valves and pumps by multilayer soft lithography, Unger M et al., Science, 2000.
Fabrication of nm-resolution and μm-range position sensor
Many companies and research groups are interested in fabrication of sensitive, low noise, high bandwidth and compact position sensors. Such a strain sensor has several applications in research and industry where positioning with nm-resolution is required. Recently sidewall doped piezoresistor has shown attractive properties upon their fabrication techniques and applications.
We offer a project for students for both semester and master projects in the filed of micro-engineering. The proposed project is linked to our ongoing development of strain sensors. The student task will be to further develop these novel sensors in collaboration with our industrial partner. We are looking for a motivated student who wants to learn multidisciplinary skills. At the end of this project you will learn micro-fabrication skills like lithography, dry/wet etching, thin film deposition, etc. as well as measurement techniques. A successful completion will serve as a template for future experiments and can be applied to different aspects of MEMS fabrication.
In this project you will learn:
- Clean room fabrication skills like photolithography, dry/wet etching, thin film deposition, etc.
- Low noise measurement techniques
- Implementation of the closed loop systems
 Hosseini, N., et al. “A monolithic MEMS position sensor for closed-loop high-speed atomic force microscopy.” Nanotechnology 27.13 (2016): 135705.