Micro total analysis systems (μTAS) promise wide applications in biology and chemistry for manipulating samples in small quantities to achieve highresolution, fast, and low-cost analysis and synthesis. There has been great progress in this field in the past decade [1]–[3]. However, large-scale applications and commercialization of μTAS have been very limited due to many challenges presented in the integration of individual microfluidic components and functionalities to complete a sample-to-answer, lab-on-a-chip system. Despite the commonly encountered tasks of integrating micropumps and microvalves in a system for fluid routing, there are great challenges in sample sorting, concentration, and manipulation for upstream sample preparation and back-end detection. In particular, these include but are not limited to: how to sort and purify molecules and cells and how to move and concentrate these materials in a micro- or nanofluidic environment. Consider an example of sample-to-answer μTAS for pathogen detection from a blood sample using DNA microarray technology (see Figure 1). A drop of blood sample was first loaded into a chip. Then one needs to perform cell sorting to capture and purify target cells (cell isolation) and wash away nontarget cells. The next step is to perform cell lysing using thermal or chemical means to get the genomic DNA contents out of the cell. After lysing, one can either purify the DNA first or go straight for a DNA amplification step to duplicate the specific genes associated with the target pathogen using polymerase chain reaction (PCR). Once the PCR is done, the PCR products may now be pumped into a chamber of DNA microarray for hybridization. The hybridization signal may be read out by an optical or electronic detection platform. The overall concept of a sample-to-answer μTAS delineated here is equally applicable in detecting and analyzing biological agents in biodefense, biomedical research, environmental, and food industry applications.