Internship Projects in 2015
Training proposals (3 months) at Laboratory for Nanotechnology (LNT)

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Project 1: System design of a chlorination and distillation process for TiCl4 production in titanium refining (2 students)

The LNT is developing a project in which titanium sponge and titanium ingot are produced through a refining process from TiCl4 by the Kroll process. The Kroll process produces metallic titanium from TiCl4 as an intermediate.

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Project 2: Design and fabrication of  recirculating water filtration system (1 student)

The LNT is developing a recirculating water filtration system using filtration membrane loaded with nanomaterials (nanosilver, nano titanium oxide...) in combination with UV light and ozone. Water from fish ponds can be pumped continuously through this system. In the filtration system, wastes mixed in water should be trapped whereas nanomaterials, UV light and ozone will kill dangerous bacteria and viruses which can cause fish diseases. Water coming out of the system and returning to the pond should be completely clean.

The trainee will have the task of designing such a water filtration system based on the individual components available.

Tutor: DOAN Duc Chanh Tin (ddctin@vnuhcm.edu.vn)
Language: English

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Project 3: Design of the mechanical frame for imprint lithography (1 student)

Imprint lithography is a relatively recent but growing technique for the patterning of surfaces with dimensions down to nanoscale. The LNT is in the process of developing this technique for obtaining patterns in the micrometer range and above as a mean of cheap surface structuring. Among the different options for implementing this technique is the pressing of a mold with the required shape onto a flat surface, the substrate, covered with a thin film of material sensitive to ultraviolet light, so called photoresist.
For that purpose, there is the need to design a mechanical tool which can ensure 2 functions:
• To place the mold in front of the substrate and press both surfaces in a very parallel way as the thin film thickness has a thickness in the range of 1 to few tens microns and the final pattern should be homogeneous; and
• To place the resulting stack into the lithography tool of the LNT to expose it to ultraviolet light which will cure the photoresist. This implies that a transparent window will need to be included in the mechanical tool, thick enough to stand the pressure to mold the thin polymer film.

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4.    Design of the mechanical frame of an optical bench (1 student)

The LNT has obtained the budget to buy the components of the optical bench it is developing for the characterization of inkjet printing. Through 2 previous internships a first level mechanical design was developed which is illustrated in the following figure. These designs allowed exploring the design space and constraints which led to a better understanding of the specifications.

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Project 5: .Building setup with sensor probes and data-logger to measure water quality parameters (1 student)

The LNT is developing a setup with sensor probes and data logger to measure water quality parameters such as pH, dissolved oxygen, salinity, temperature, conductivity, ammonia... The characterization bench includes a tank receiving the water sample with several probes and data-logger connected with PC to record the measurement data.

The trainee will be tasked to place as well as connect the probes to the data-logger and PC. A user interface will then be developed to allow the automatic record of the measured parameters.

Tutor: DOAN Duc Chanh Tin (ddctin@vnuhcm.edu.vn)
Language: English

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Project 6: Physical and software interface for a gas bench (1 student)

The LNT is engaged for some years on research in RFID sensors (Radio-Frequency Identification). A sensor was developed 2 years ago to measure the evolution of meat and cheese in situ without the need for a specific sensing part, i.e. the RFID tag itself acts as a sensor. The current development targets an RFID sensor with a sensitive material in order to gain specificity to a particular target gas. At first the focus is on ammonia sensing.
To test this sensor, a specific gas bench is set up which should be transparent to electromagnetic waves. In this case the bench is made of glass (schematic below). In the last part of the design of this bench it is necessary to properly wire the ammonia sensor, 2 mass flow meters, a Vector Network Analyzer (VNA) and an RFID reader to enable a central command of the bench.

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Project 7: Design of the control electronics of an optical bench (2 students)

Thanks to 2 previous internships, the design of the control electronics of the optical bench that the LNT is developing reached a good level. It is represented in the schematic below. For the time being it however has several limitations:
•    The signal generated by the MBED is only able to control one nozzle at a time;
•    The signal is limited to 3.3V while the printhead needs up to 40V for a proper ejection of the droplets; and
•    It is lacking a friendly user interface.

The trainees will get acquainted with the inkjet printing process and the current design of the control electronics of the optical bench. As the first control design is now developed, the topic expanded and it is divided in 2 topics:
-    The first is related to the design of the control of the printhead as schematically described above,
-    The second topic is related to the design of the synchronization of the printhead, the lighting system and the camera.

1.    The trainee will perform the measurement of the current drawn by one nozzle when fired at 40V, directly in the printer following the procedure developed previously. He/she will then study options to achieve the required control based on programmable components available on the market. The same will be done to provide the necessary amplification on both channels.
2.    The trainee will review the existing constraints on the propagation delay in the connecting wires of the bench in order to ensure the ability to achieve a 100ns delay resolution. This will include the measurements of the propagation delays in available components. A model will be proposed with all known delays, including switching delays of electronic components. A first design of a printed circuit board will be proposed which will include recommendations on interconnecting cables to be used to reach an overall control of the bench. If time allows the trainee will specify and search for a stroboscopic lighting system compatible with the printhead.
Such fast phenomenon observations are democratizing thanks to gradually decreasing cost of high speed cameras. The challenges brought out from a control of a high speed observation system will allow the trainees to explore solutions for reaching a working bench.

Tutors: DANG Thi My Dung (dtmdung@vnuhcm.edu.vn), Eric Fribourg-Blanc (fberic@vnuhcm.edu.vn)
Language: French & English