Semester Projects

Metallic nano-objects and their arrays exhibit peculiar functionalities that can be exploited in several scientific fields. Such constructs can indeed be used as catalysts for arrays of semiconducting nanowires, in light trapping and extraction systems, as efficient transparent electrodes for optoelectronic devices, and in sensing and biological applications. Their fabrication remain however difficult and costly, especially over large area substrates. In this project we propose to investigate a novel fabrication approach of these nano-structures that is simple and scalable. The objective is to demonstrate a 2D and a 3D ordered array of nano-objects using simple nano-imprint and thin-film processing approaches.

Pressure-sensing flexible systems have drawn a lot of attention due to their wide applications in touch displays, electronic skin, health care and biomonitoring (such as pulse wave monitoring), etc. Several approaches have been proposed in recent years, such as microstructured polydimethylsiloxane films which are integrated into the gates of an array of organic field-effect transistor ^[1,2] and artificial skin^[3]. However, these approaches are complex and costly, and especially hard to realize over large scales. In this project, we propose a novel, high efficiency, and low-cost strategy to fabricate large scale fiber devices that can be sensitive to pressure. Thermal drawing will be a preferred method to fabricate the fibers and different kinds of materials, such as metal, polymer and carbon materials will be combined to achieve the targeted functionalities. The main aim of this project is to optimize the fiber devices with respect to its structure, the material selection and processing parameters. Students will learn about pressure-sensing devices design, fiber fabrication methods as well as structural and electronic characterization tools.

Experimental and modelling tools:

• Multi-material preform fabrication and thermally drawn technique
• Electronic characterization
• Mechanical properties characterization (viscosity, etc.)
• Materials characterization (Optical Microscopy, SEM)

[1] S.C.B Mannsfeld, et al. Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers. Nat Mater, 9(2010) 859.

[2] G. Schwartz, et al. Flexible polymer transistors with high pressure sensitivity for application in electronic skin and health monitoring. Nat Commun, 4(2013) 1859.

[3] D. Kim, et al. Epidermal electronics. Science, 333(2011)838.

Non-linear second or third harmonic light generation is of significant relevance in many integrated optical circuits today. Efficient signal conversion can open up new possibilities in optical computation or supercontinuum generation.

Controlled dewetting provides an interesting and efficient way to obtain ordered nanostructures of various optical materials. This process can be an efficient platform to enhance second or third order harmonics  for strong incident light beams. Beyond dewetted structures, this project will also focus on non linear light generation in particular monocrystalline systems.

Experimental :

• Thermal Evaporation
• Nanoimprint techniques
• Optical Characterization

Basic but no advanced knowledge in optics is required at the start of this project.

Soft materials and architectures that conform to and create an intimate matching with soft and non-planar body surfaces offer intriguing opportunities in biology and medicine. In the domain of shape-morphing, magnetic soft machines are highly desirable for diverse applications in minimally invasive medicine, wearable devices, and soft robotics[1,2]. Scaled up thermal drawing manufacturing process will allow to optimally design ferromagnetic domains in soft, thermoplastic materials encoded with complex programmed shapes. Different architectures inside the magnetic soft fibers will be manufactured which will provide an overview of the design capabilities with sensing integration. This project is focused on manufacturing scaled-up ferromagnetic, multi-material fibers towards building intelligent surgical tools, smart textiles for actuation and sensing[3-5].

Experimental and modeling tools:

• Multi-material perform fabrication and thermally drawn technique
• Mechanical properties characterization (rheology, mechanical testing, etc.)
• Materials characterization (Optical Microscopy, SEM)
• Engineering Design
• Signal Processing
• Motion Tracking

References:

1. Qu, Yunpeng, et al. “Superelastic multimaterial electronic and photonic fibers and devices via thermal drawing.” Advanced Materials 30.27 (2018): 1707251.

2. Kim, Yoonho, et al. “Ferromagnetic soft continuum robots.” Science Robotics 4.33 (2019).

3. Kim, Yoonho, et al. “Printing ferromagnetic domains for untethered fast-transforming soft materials.” Nature 558.7709 (2018): 274-279.

4. Alapan, Yunus, et al. “Reprogrammable shape morphing of magnetic soft machines.” Science advances 6.38 (2020): eabc6414.

5. Kim, Yoonho, et al. “Telerobotic neurovascular interventions with magnetic manipulation.” Science Robotics 7.65 (2022): eabg9907.

Thermal drawing is a powerful technique to realize fibers incorporating a variety of materials into intricate structures. A few years ago, our group demonstrated the thermal drawing of thermoplastic elastomers, paving the way to new types of applications, in particular in soft robotics and wearable devices[1,2]. Based on these elastomers, several soft composites have also been developed and integrated into thermally drawn fibers to create soft actuators[3] or soft mechanical sensors[4]. However, one class of materials remains unexplored: soft semiconductors.
In this project, we propose to study the feasibility and potential of soft semiconductors in thermally drawn fibers.

Experimental tools:

• Material and preform preparation (solution mixing, spin coating, hot pressing…) 
• UV-Vis Spectroscopy
• Mechanical properties characterization (rheology, tensile test…)

References:

[1] Y. Qu, T. Nguyen-Dang, A. G. Page, W. Yan, T. Das Gupta, G. M. Rotaru, R. M. Rossi, V. D. Favrod, N. Bartolomei, F. Sorin, Advanced Materials 2018, 30, 1707251.
[2] A. Leber, C. Dong, S. Laperrousaz, H. Banerjee, M. E. M. K. Abdelaziz, N. Bartolomei, B. Schyrr, B. Temelkuran, F. Sorin, Advanced Science 2023, 10, DOI 10.1002/advs.202204016.
[3] H. Banerjee, A. Leber, S. Laperrousaz, R. La Polla, C. Dong, S. Mansour, X. Wan, F. Sorin, Advanced Materials 2023, 35, DOI 10.1002/adma.202212202.
[4] A. Leber, S. Laperrousaz, Y. Qu, C. Dong, I. Richard, F. Sorin, Advanced Science 2023, DOI 10.1002/advs.202207573.