Resumen de Analysis and design of a capillary driven blood plasma separation microfluidic device
Hojjat Madadi
Recently, the emergence of lab-on-a-chip devices has seen in a variety of applications especially in clinical analys is and diagnostics. ln particular the lack of suitable microdevices for separation of plasma from whole blood is a barrier to achieve a reliable lab on a chip (LOC) blood test. In order to address this issue, a novel self-driven high throughput blood plasma separator microchip is introduced as a first step to a miniaturized blood analys is. PDMS (Polydim ethylsiloxane) is utilized as the base material for the microdevice fabrication to ens ure the biocompatibility, the disposability(single-use to avoid contamination) and the low cost ofthe system for the mass-manufacturing. One of the characteristic features ofthe presented m icrodevice is that it needs to work just by capillary pressure eliminating the need of external sources. The requested capillary pressure to drive blood through the microdevice is derived via PDMS modification byanalyzing different surfactants, which are mixed with pre-cured PDMS to achieve a stable hydrophilic character. Furthermore, a diamond microchannel integrated micropillar (dMIMP) pump with high throughput and with a resistance flow 35.5% lower than a circular based micropillar pump (cMIMP) has been developed. For this purpose, the pressure drop and flow resistance of a lam inar flow through low aspect ratio MIMPs with different shapes and geometrical parameters are experim entally, numerica lly and analytically determined. In order to characterize the fabricated microcapillarypumps in PDMS, a novel and simple fabrication technique is introduced to overcome the PDMS deform ation under high-pressure operation. The presented fabrication technique combines the use of stiff PDMS (1 0:2, the ratio between polymer base and cross liking agent) and a thin coating layer of the UV curable thiolene resin as supporter (Norland Optical Adhesive 63) on the fabricated PDMS microchannel. Finally, using all the achieved results in the material property and microcapillary pump design in the last steps, a novel selfd riven high throughput microfluid ic chip for blood plasma separation is designed and fabricated. The presented microdevice can successfu lly separate more than 0.11JL of plasma from a whole human fresh blood drop (51JL) without the need of external forces with high efficiency(more than 90%) and reasonable time (3 to 5 minutes). The achieved plasma volume (0.1 IJL) in 10 1Jm-depth collected channels ofthe presented self-driven microdevice paves the path to integrate this microfluidic circuit in a portable medical point-of-care-testing (POCT) for doing different blood analysis.
