This thesis describes a series of processes and devices, which have been developed to improve the functionality and ease of manufacture of micro-fluidic systems, such as labon-a-chip devices.
A novel fabrication technique has been developed for the production of large
multilayer travelling wave electrode arrays without the use of via-holes thus
significantly improving the device reliability. Also described are new processes, which have been developed for the accurate fabrication of micro-fluidic channels from low cost materials such as glass and polymers.
Both capacitive and resistive based sensors were designed and incorporated into
lab-on-a-chip style devices for the measurement of fluid flow and the detection of individual particles or particle suspensions within the channel. With an aim to using
these sensors in disposable devices, the complexity of the sensing element and interface electronics were minimised where possible. Through innovative electrode design, temperature compensation was incorporated into the sensor itself eliminating the need for additional components.
Continuing the desire for disposability and integration, simple device imaging
systems were developed. To aid incorporation of these systems into lab-on-a-chip devices the optical components, if any, were fabricated as part of the device structure. This integration produced good quality images allowing useful measurements to be taken.
A key area of investigation in micro-fluidics is sample preparation. Computer
simulation tools were used to aid in the design of a micro-fluidic system capable of automating the labour intensive process of sample conductivity reduction. This is achieved through improvements to the basic H-filter design, so facilitating the significant drop in the conductivity of whole blood necessary for dielectrophoretic measurements. The final design was tested and there was good agreement between the experimental and computational results