Blood Extraction and Cell Sorting Integrated on Single MEMS Device

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$Document biologie : Blood Extraction and Cell Sorting Integrated on Single MEMS Device$ biologie

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publié le 17/03/2008

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Résumé

Lab-on-chip using mems fabrication technology concepts have been the focus of many different research groups in the past decades. This research topic has been investigated extensively for the many advantages that a lab-on-chip device can potentially offer to the medical field. mems devices stand to reduce the sampling sizes required to perform medical analysis, which in turn will minimize the impact biological sampling will have on patients [1]. Because lab-on-chip devices are portable, unlike most traditional lab systems, they will reduce chances of contamination and human error, and increase turn around time of medical analysis.

The research done in this area has produced many promising advances in the extraction of biological tissues and fluids and the analysis of these tissues and fluids. However, one important aspect remains fairly uninvestigated; how to bridge the gap from direct extraction to analysis, taking raw samples and converting them into useable specimens for analysis [2]. cellular analysis using mems devices typically uses presorted, prestained, or precultured samples. The processing to do these preliminary steps is done with traditional lab equipment. A lab-on-chip device will prove to have the greatest efficiency and greatest usefulness if the entire system is integrated onto one single device. The following proposed research presents a complete lab-on-chip system, integrating two previously designed mems devices. These two devices will perform the extraction and the separation of white blood cells from blood. Additionally, this device has been designed to be flexible and easily packaged so that incorporation of additional analysis tools with this device will be straightforward.

blood consists of several different components. Plasma is the fluid in which blood cells are suspended. Within plasma, there are red blood cells, white blood cells, and platelets. Red blood cells are the most numerous components of blood, with approximately 4 million red blood cells in each cubic millimeter of blood [2]. White blood cells, or leukocytes, are the body’s main defense against disease and infection, which makes the examination of white blood cells important for many different aspects of medical treatment and research. Typically, there are somewhere between 5000-7000 white blood cells per cubic millimeter of blood [2]. Because the concentration of white blood cells is much less than red blood cells, separating white blood cells from the remaining content of blood is needed before adequate examination of white blood cells can be performed. In a lab setting, this is typically done by performing centrifuging. This process produces less than ideal results because of low yield and damaged cells.

The preliminary design laid out in the following proposal consists of a microneedle designed to pierce the skin and penetrate a vein. Using micropumps, blood is drawn from the vein at a controlled rate. blood is forced into a chamber that effectively separates the white blood cells from the rest of blood’s content. This method of separation is performed by emulating a natural biological process that occurs regularly in humans and other mammals [3].

Sommaire

Physiological sorting process
1. Leukocyte capture in a biological system
2. Cell adhesion research
Design of cell sorting chamber
1. Previous work in MEMS
2. Proposed design of cell sorter
Microneedle design
1. General design
2. Force analysis
Fabrication
Basic microneedle/cell sorter use procedure
Proposed work and developments for the future