Flow Lithography (Flow Lithography (Lectures and Exercises))

Structured microparticles, with unique shapes, customizable sizes, multiple materials, and spatially-defined chemistries, are leading the way for emerging ‘lab on a particle’ technologies. These microparticles with engineered designs find applications in multiplexed diagnostics, drug delivery, single-cell secretion assays, single-molecule detection assays, high throughput cytometry, micro-robotics, self-assembly, and tissue engineering. In this course, we will learn about the state-of-the-art particle manufacturing technologies based on flow-assisted photolithography performed inside microfluidic channels. Important physiochemical concepts will be discussed to provide a basis for understanding the fabrication technologies. These photolithography technologies will be compared based on the structural as well as compositional complexity of the fabricated particles. Particles will be categorized, from 1D to 3D particles, based on the number of dimensions that can be independently controlled during the fabrication process. After discussing the pros and cons of the individual techniques, important applications of the fabricated particles will be covered.
Course topics:
1 Introduction to flow assisted lithography
2 Important physio-chemical concepts
2.1 Polymerization inside microfluidic channels
2.2 Single-phase flows in microfluidic channel
2.3 Microchannel material
2.4 Multi-phase flow in microfluidic channel
2.5 Particle-templated droplet formation
3 Categorization based on particle dimensions
3.1 1D, 1.5D, 2D, 2.5D, and 3D particles
4 Flow-assisted particle fabrication techniques
4.1 1D particles: droplet microfluidics lithography…
4.2 1.5D particles: non-spherical lithography…
4.3 2D particles: continuous flow lithography…
4.4 2.5D particles: hydrodynamic flow lithography…
4.5 3D particles: inertial flow lithography…
5 Applications of particles
5.1 Particle-templated droplet formation
5.2 Cell-laden hydrogels (tissue scaffolds)
5.3 Diagnostics assays
5.4 Cell culture on the particles (cell-carrier)

After participation in this course, the student is able to:
1. compare various continuous and stop flow lithography techniques for microparticle fabrication
2. describe fabricated particles based on the dimensional complexity from 1D to 3D
3. distinguish the fabrication techniques based on their ability to fabricate complex particles
4. understand the use of these customizable particles in various biomedical applications

'Advanced Microfluidics (lectures and exercises)' course and 'Advanced Microfluidics Simulations (practical)' course are recommended.

The module will comprise lectures with integrated exercises (4SWS). The lectures will introduce the students to a range of microfluidic fabrication techniques, from very basic to very advanced. The course will provide an overview of the field of flow assisted lithography to the students and would help them incorporate some of the acquired knowledge in their research projects in the future. During the exercise, the students will discuss and solve problems associated with microparticle fabrication systems. This will help the students to achieve a deeper understanding of the topics, and to apply the taught concepts to practical tasks. This will help the students to acquire the teaching goals, which are listed above.

PowerPoint presentations will be used during the lectures, and made available via Moodle after each lecture.

Reference book:
1. Chu, L.-Y. & Wang, W. Microfluidics for Advanced Functional Polymeric Materials. Microfluidics for Advanced Functional Polymeric Materials (Wiley-VCH Verlag GmbH & Co. KGaA, 2017). doi:10.1002/9783527803637
Reference review articles:
2. Tian, Y. & Wang, L. Complex three-dimensional microparticles from microfluidic lithography. Electrophoresis 41, 1491–1502 (2020).
3. Li, W. et al. Microfluidic fabrication of microparticles for biomedical applications. Chemical Society Reviews 47, 5646–5683 (2018).
4. Choi, A. et al. Recent advances in engineering microparticles and their nascent utilization in biomedical delivery and diagnostic applications. Lab Chip 17, 591–613 (2017).
5. Zavada, S. R. et al. Radical-Mediated Enzymatic Polymerizations. Int. J. Mol. Sci. 17, (2016).
Additional literature in terms of peer reviewed articles will be shared.

Written exam: 100%
Duration of the exam: 90min
In the written exam, the students demonstrate their knowledge of the microfluidics-based lithography processes for particle fabrication and their use in various applications by answering short questions.