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Numerous applications in biology and medicine requires efficient and reliable separation of cellular or sub-cellular components from blood for disease diagnosis, genetic analysis, drug screening, and therapeutics. However, analyzing undiluted whole human blood is challenging due to its complex composition of hematopoietic cellular populations, plasma and sub-cellular components such as nucleic acids, metabolites, and proteins. In addition, current state-of-art for blood fractionation relies on multi-step density-based centrifugation or flow cytometry which are manual, time-consuming and unable to process whole blood. In this dissertation, we aim to demonstrate a multi-functional, low-cost microfluidic acoustic streaming platform to enrich and characterize cellular components from whole blood and utilize blood’s sub-cellular components for simultaneous detection of multiple infections. First, we present Lateral Cavity Acoustic Transducers (LCATs) that enables (1) the sorting of undiluted donor whole blood into its cellular subsets (platelets, RBCs, and WBCs), (2) the enrichment and retrieval of breast cancer cells (MCF-7) spiked in donor whole blood at rare cell relevant concentrations (10/ml), and (3) on-chip immunofluorescent labeling for the detection of specific target cellular populations by their known marker expression patterns. Our approach thus demonstrates a compact system that integrates upstream sample processing with downstream separation/enrichment, to carry out multi-parametric cell analysis for blood-based diagnosis and liquid biopsy blood sampling. Second, we integrated a passive (spiral inertial microfluidic device) and an active device (LCAT) for high-throughput separation, enrichment and release of specific target cellular population (such as larger side-population (SP) of DU-145 cells from tissue biopsy or larger monocytic cell population from blood sample). After optimization with particles spiked in blood, this platform removed >90% of the smaller cells, such as RBCs in a blood sample or smaller cancer cells in a heterogeneous cell line, and provided 44,000x enrichment from remaining sample within 5 minutes of device operation. Third, since whole blood comprises not only cellular subsets, but also sub-cellular components, we utilized the antibodies in both blood serum and saliva for the multiplexed screening of HIV, HPV and HSV within 17.5 minutes. We integrated this acoustic microstreaming platform with a protein microarray and verified reactivity of patient antibodies with HIV, HPV and HSV antigens. This integrated microfluidic protein array platform is the basis of a potent strategy to delay progression of primary infection, reduce the risk of co-infections and prevent onward transmission of infections by point-of-care detection of multiple pathogens.

In this work, a new passive on-chip blood cell/plasma separator using self-assembly of microspheres as a physical filter and a smart on-chip dynamic blood cell/plasma separator based on a series of pressure pulses in microchannel have been proposed, developed, and successfully characterized for as a part of the disposable polymer lab-on-a-chip point-of-care testing (POCT) clinical diagnostics.A method for self-assembly crystallization of silica microspheres has been investigated for the application as a physical filter. Combination of the vertical deposition method using capillary forces on a hydrophillic substrate with plasma polymer surface modification is used for developing selectively deposited self-assembled microspheres over a specific site of a microchannel. The developed 3D self-assembled silica microspheres over the filter region of the microchannel with their uniform porosity and structure have been fully characterized for separating blood cell/plasma in microchannel. Secondly, a new pulse-assisted dynamic separation technique has been introduced and developed for the application of blood cell/plasma separation without physical filters. The dynamic separation has been attained from the differential forces exerted by applying high amplitude, short duration pressure pulses to the blood sample in microchannels. In addition, the motion of the particles in liquid suspension solution in microchannel experienced by both various forces on particles and pressure pulses on suspension solution has been simulated to validate the principle and to optimize performance by computational analysis and parametric study. The developed pulse-assisted dynamic separator has been successfully developed and characterized on blood cell/plasma from human whole blood sample in microchannel.An on-chip pressure actuator for transporting a fixed-volume of the biofluid sample into a desired site in a lab-on-a-chip or mTAS has been investigated and implemented. A new solid energetic material and its thermolysis by localized heat output from an infrared (IR) source is used for producing non-toxic and biologically inert nitrogen gas to deliver the fixed-volume of sample on demand. A solid energetic material has been explored and fabricated on the chip with simple and cost-effective method.

In this work, an on-chip magnetic bead separator in an aqueous solution has been implemented on a plastic substrate. The technique has been successfully characterized in separating magnetic microspheres of 4.1 µm diameter from a suspension solution in DI water. µTAS (Micro Total Analysis System) frequently need to deal with bioparticle suspensions in solution. Separation of certain bioparticles is often desirable. Traditionally, methods like physical filtration have been used to separate biomolecules from suspension solutions. These methods, though well-established are not suited for integration on to mass-fabricated plastic lab-on-a-chip devices. The method developed in this work relies on the differential force exerted by application of high amplitude, short duration pressure pulses on a suspension solution, resulting in separation of suspended particles. From a dispensed volume of 500 nl of the suspension solution, up to 300 nl, or 60 % of volume has been cleared of particles.