| Genetics tests and assays have enormous scope of applications in biotechnology and medicine. Implementation of these series of monotonous biochemical reaction steps in microfluidic devices has lead to benefits in time, flexibility of operation, and cost of the reagents and systems. The main objective of this thesis is the development of components and related technologies for the realization of an integrated microfluidic system for these assays. Some of the critical technologies required are: (a) a detector to convey information from the molecular level to user level, (b) microvalves for control and isolation of reagents in the microchip and (c) micropumps for the transport of nanovolumes of the reagents across the chip.; All the three critical areas have been analyzed and developed. An inline electrochemical detector, capable of detecting 14.5 amol of electroactive Ferrocene carboxylic acid (FeAc), has been developed. It uses a novel electrochemical cell and supporting electronics design to eliminate the problem of gas evolution. FeAc was also tagged to calf thymus DNA sample and the DNA detected.; A novel electrokinetic pumping mechanism has also been developed, which uses scaling in microsystems to eliminate pressure flow and allow electrokinetic flow, also eliminating gas evolution normally associated with electrokinetic pumping by using the non-linearities in the system. Pumping velocities of 10 μm/s have been achieved.; An inline microvalve using Paraffin as the microactuation material has been developed. Burst pressures of 23 psig have been demonstrated. The valve is found to fully close at power as low as 35 mW.; While the devices presented here are stand-alone devices, the direction of research has been highly influenced by the goal of incorporating these devices into a complete genetic analysis system. Hence the fabrication techniques used are all low temperature processes; the materials are compatible, plastic-based, and the devices easily integrable. |
