|dc.description.abstract||Disease detection is of utmost importance for initiating appropriate treatment and efficient preventative measures. Therefore, providing an inexpensive, fast and robust alternative to the current detection techniques, whilst still upholding the selectivity and sensitivity levels, are highly sought after. The integration of a microfluidic sample delivery system to a biomedical diagnostic device could help realize this.
In this work we have developed microfluidic channels capable of integration with miniaturized biomedical diagnostic devices for improved performance. A two-layer passive mixing channel was developed as a fluid delivery system to an optical biosensor. The passive mixing structures were embedded in the ceiling of the channel and increased the mixing and surface homogenization process otherwise limited by diffusion.
The microfluidic devices developed herein were fabricated using maskless photolithography and PDMS soft lithography, enabling rapid prototyping of many different channel designs. Thus, the evaluation of the mixing enhancement when varying several geometrical parameters was possible. Confocal microscopy was implemented to observe the mixing of the fluid flow at several different sections throughout the channels. This provided information regarding the rate of mixing for the bulk fluid and at the fluid layer closest to the surface opposite the mixing structures.
Microfluidic channels can also be used as the main device for inducing deformation of cell shapes. There are several ways in which this can be performed, where one is to include a constricted section within the device. This constriction is typically smaller than the cell dimensions, thus inducing deformation as the cell flows through this section. The level of cell deformation is a label-free, mechanical signature indicating the health of the cell and can be used as a marker for disease detection. These devices can provide rapid analysis of the mechanical state for a large number of cells from a micro-liter sample volume. Such a channel was fabricated as a high-throughput device capable of inducing deformation to red blood cells, providing information regarding the mechanical properties.
Overall, this work provides insight into different uses of microfluidic channels for miniaturized biomedical diagnostic devices, utilizing PDMS as the channel material. The work indicates that appropriate channel designs has potential for improving biosensor performance, as well as the possibility to act as a key component in imposing cell deformation as a label-free diagnosis basis. The focus on microfluidic channels for biomedical diagnostics stems from their capability of handling small sample volumes and increasing sensitivity whilst reducing overall cost, contributing to the development of efficient diagnostic devices.||en_US