Cells are the smallest living units and together they form all living organisms on earth. The cells are not only the building blocks of all living things, they also possess the most important information about life. A deeper understanding of these units may reveal hidden secrets about difficultly cured diseases, memory and learning, among others. Today’s techniques have problems such as low sensitivity, lethal preparation steps for the cells and overlaps in result spectra. Microfluidics has shown to be a useful tool allowing improved dynamic control, high throughput and sensitivity in nanoliters. The aim with this project is to design a microfluidic system for future integration with photonic sensors. Three different designs were developed, one design with the aim to integrate with photonic sensors and two for cell trapping only. Simulations and analytical calculations were performed to verify the requirements of single cell trapping. Simulation and analytical calculation results consorted, except for the ladder design. Moreover, strength calculations were performed for the sensor, to verify that it could handle the high pressures. A fabrication process was developed and an OSTE polymer was chosen as a suitable material. The transparency of the OSTE for fluorescent signals was studied. Results from the fabrication show proper lithography and molding as well as flow through channels. However, bubbles tend to appear in the channels. A rough surface of the chip appeared to primarily come from defects and filth on mask and mold. Three different connector solutions were tested, but they could not stand the high pressures. The work in this project has taken the development one step closer to the final goal to integrate photonic biosensors with a microfluidic system enabling single cell sensing.

This work presents detailed numerical calculations of the dielectrophoretic force in octupolar traps designed for single-cell trapping. A trap with eight planar electrodes is studied for spherical and ellipsoidal particles using an indirect implementation of the boundary element method (BEM). Multipolar approximations of orders one to three are compared with the full Maxwell stress tensor (MST) calculation of the electrical force on spherical particles. Ellipsoidal particles are also studied, but in their case only the dipolar approximation is available for comparison with the MST solution. The results show that the full MST calculation is only required in the study of non-spherical particles. / Singapore-MIT Alliance (SMA)