Synthetic gel particle formation for acoustofluidic applications

Abstract

Cancer cell detection by particle sorting systems is a very challenging field which could help to discover cancers at an earlier stage. Acoustophoresis used as a particle sorting system is based on the difference between the acoustic properties of particles and the medium. Using a standing acoustic wave, the particles with the equivalent acoustic properties are focused at the same point in the channel. During the experiments on acoustophoresis systems some parameters can be adjusted such as the flow rate, the concentration, the frequency of the acoustic wave, etc. Microparticles such as silica-based, polystyrene and PMMA particles are mainly used as test particles to replace the cells. Artificial test particles have more defined properties enabling to repeat under the same conditions all experiments and have an easier handling. However, these particles are not reproducing very accurately the acoustic properties of human cells. Ideally, the test particles should have the same size and have acoustic properties as close to the cells that we want to investigate as possible. The work carried out in this project has been oriented around gel particles as a solution to replace the particles found on the market that are used as test particles in acoustofluidic systems. Agarose gel particles within the size range of the human cells have been produced using different microfluidic droplet generator chips. The gel particles was tested in acoustophoresis devices in a water medium and they interacted with the acoustic field. The smallest particles with a diameter of about $7-10$ $\mu m$ were circulating around in the vortices of the acoustic streaming. Some other gel particles had a motion towards the anti-node. Even if a real behavior of the particles in the water buffer has not been determined, it points to a possible way of producing gel test particles for a further use in acoustofluidic systems.

Popular Abstract

Producing gel particles to mimic human cells in an acoustofluidic system.

Acoustofluidics is a promising technique to move particles with a sound wave. This sound wave applies a force to particles in a suspension. This force is directed in the cross section of the channel. This technique is particularly promising for cancer cells detection. Because the particles can be moved in the lateral direction, different outlet at the end of the fluidic chip could allow to increase the concentration of the cancer cells if they are focused in the same place. This increasing concentration could allow to detect some cancers at earlier stage that are not visible with standard techniques because the amount of cancer cells would be too low for the detection. In the development of this technique different particles are used to mimic the cell behavior when the acoustic force is applied to them. No commercially available particles are manufactured for the specific use of mimicking the cell behavior in an acoustofluidic system. The main test particles used are polystyrene beads. However their properties are not fully able to mimic completely the acoustic properties of cells. Indeed, these particles are not soft enough compared to the cells and this hardness implies that they feel a different acoustic force than the cells. The idea of this project is to produce a new type of particles that could mimic the acoustic cell properties and replace the polystyrene beads. This work focused on the production of agarose gel particles. The agarose is a sugar and when it is mixed with water it forms a gel structure. This gel structure is softer than polystyrene and could provide better results regarding the cell mimicking. The agarose gel particles were formed by using a droplet generator chip to get spherical test particles. Once produced these gel test particles were collected and tested in the acoustofluidic system. The gel particles interacted with the acoustic wave and moved in the channel when the acoustic force was applied however further measurements are still needed to investigate if their properties mimic the cells as expected.

• author: Valery, Thibaut
• supervisor: Richard Soller
• organization: Department of Biomedical Engineering
• course: BMEM01 20221
• year: 2022
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: agarose gel particles, acoustofluidics, droplet generation, microfluidic chip
• language: English
• additional info: 2022-19
• id: 9099449
• date added to LUP: 2022-09-09 14:07:32
• date last changed: 2022-09-09 14:07:32