While detection of species using biochips has progressed a lot, the separation and enrichment of bio-particles from biofluids is an unaddressed need in bioanalytical applications. Examples include the purification of nucleic acids from human fluidics such as serum for next-gen sequencing or for detecting infectious diseases, complex extraction steps for protein purification or the isolation of exosomes for diagnosing cancer. Bio-particles include nucleic acids, proteins, extracellular vesicles, viruses and bacteria. Current technologies such as filtering, centrifugation, or liquid chromatography can separate or enrich bio-particles, but they are difficult to integrate in small microfluidic devices. The difficulty of bio-particle separation is a major bottleneck that prevents many microfluidic techniques from being widely used in commercial applications. The focus of this PhD is to develop an electro-capturing method and device that can separate and enrich biomolecules in a microfluidic format.
The electrical properties of bio-particles, such as charge or dielectric constant, allow them to be effectively manipulated directly by electric fields. This can be combined with indirect manipulation through electrokinetically generated flows (electroosmotic and electrothermal). Electrical bio-particle manipulation provides many potential advantages over existing techniques such as simple structure, low fabrication complexity, less fluidic transfer steps, programmable operations, etc. One successful example in literature is dielectrophoresis where relatively big particles (such as cells) can be polarized and actuated in AC electric field. Recent efforts also indicate that DNA dielectrophoresis is possible. However, (di)electrophoresis of small bio-particles such as extracellular vesicles or proteins are less studied nor clearly understood. A few fundamental questions are still to be answered: what determines the electrical polarization of bio-particles? Is it possible to control the bio-particle polarization so as to separate different bio-particles? How many physical effects may participate in electrical bio-particle capturing as the particle size scales down?
To answer these questions, the electrical properties of bio-particles and the consequential behavior will be studied in this PhD by theoretical modelling and experimental verifications. Analytical bio-particle modelling and possibly finite element modelling will be used for theoretical understanding of the bio-particle electrical characteristics. For experimental verifications, the candidate will perform hybrid electrical and microfluidic design and fabrication in imec's cleanroom. The device will be characterized and used for bio-particle capture measurements. This topic will be supervised and supported by a team of physicists, biochemists and engineers in the imec life sciences department.
Required background: physics, electrical engineering
Type of work: 10% literature study, 40% data analysis and modelling, 50% device fabrication and characterization
Supervisor: Liesbet Lagae
Daily advisor: Wim Van Roy, Chengxun Liu
The reference code for this position is 2020-087. Mention this reference code on your application form.
Chinese nationals who wish to apply for the CSC scholarship, should use the following code when applying for this topic: CSC2020-46.