The research anticipated that several of the technologies developed from this research - i.e., the PCR-microchip, the particle counter microchip, the molecular beacon labeling protocols, and the LDR-SERS techniques - would be integrated into a unified portable biosensor that would perform the preparation, amplification, and multiplexed optical detection of DNA. A fully portable testing platform was developed for demonstrating the PCR-based detection microchip technology. After 4 months of testing using a variety of forensic DNA samples, subsequent work developed a multiplexing instrument that featured spectral optics and multiplexed molecular labels; and two additional platforms were explored in order to achieve higher multiplexing capability. In addition, researchers developed novel microfabricated fluid pumps that are driven by low voltages and can be readily integrated into lab-on-a-chip devices. These novel pumps promise to eliminate all reagent handling duties currently performed by the end user. This work will enable portable biosensors that accept disposable cartridges preloaded with reagents. One additional platform developed was a fluorescence-activated particle counter microchip for multiplexed scoring of DNA targets. Much of the work performed focused on the use of quantum dots as molecular probes, specifically the use of quantum dots as molecular beacons. Further, the researchers developed a new approach to SNP detection through the application of Surface Enhanced Raman Scattering (SERS) to the Ligase Detection Reaction (LDR). This technique avoids the problem of spectral overlap that limit's the number of reactions conducted in parallel by fluorescence-based systems. 33 figures, 3 tables, and an 82-item bibliography