Volume fraction profile and a simple model of erythrocyte sedimentation.

<p>The height of the liquid column <i>h</i> remains constant in the process of sedimentation. The height of the plasma zone <i>h</i>_<i>p</i> and the volume fraction at the bottom of the blood column both increase. The velocity of the boundary between the zones changes with time. (A) Experimental observation of variation of volume fraction profile during sedimentation. Suspension of washed erythrocytes in pure plasma, initial hematocrit = 38.5%. (B) Simplified model of erythrocyte sedimentation.</p

Time-dependent changes in blood conductivity during sedimentation.

<p>Three samples of washed erythrocyte suspensions in pure plasma were prepared at hematocrit (HCT) = 35, 45, and 55%. (A) The conductivity of blood increased slightly during the first minute of observation and then decreased for more than 1.5 h. The conductivities of the disaggregated erythrocyte suspension were <i>σ</i> = 0.588, 0.468, and 0.355 S/m, at HCT = 35, 45, and 55%, respectively. The conductivity of the deposit on the bottom of the chamber was approximately 0.175 S/m at the end of the sedimentation, regardless of the initial HCT. (B) Initial changes in blood conductivity at HCT = 35%. The maximum value of the initial increase in conductivity was about 0.036 S/m at 18s. (C) The maximum value of the initial increase in conductivity was 0.028 S/m at 31 s (HCT = 45%). (D) The maximum value of the initial increase in conductivity was 0.027 S/m at 60 s (HCT = 55%).</p

Erythrocyte sizes and electrical properties.

<p>Erythrocyte sizes and electrical properties.</p

On-Chip Parylene‑C Microstencil for Simple-to-Use Patterning of Proteins and Cells on Polydimethylsiloxane

Polydimethylsiloxane (PDMS) is widely used as a substrate in miniaturized devices, given its suitability for execution of biological and chemical assays. Here, we present a patterning approach for PDMS, which uses an on-chip Parylene-C microstencil to pattern proteins and cells. To implement the on-chip Parylene-C microstencil, we applied SiO<i>x</i>-like nanoparticle layers using atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) of tetraethyl orthosilicate (TEOS) mixed with oxygen. The complete removal of Parylene-C from PDMS following application of SiO<i>x</i>-like nanoparticle layers was demonstrated by various surface characterization analysis, including optical transparency, surface morphology, chemical composition, and peel-off force. Furthermore, the effects of the number of AP-PECVD treatments were investigated. Our approach overcomes the tendency of Parylene-C to peel off incompletely from PDMS, which has limited its use with PDMS to date. The on-chip Parylene-C microstencil approach that is based on this Parylene-C peel-off process on PDMS can pattern proteins with 2-μm resolution and cells at single-cell resolution with a vacancy ratio as small as 10%. This provides superior user-friendliness and a greater degree of geometrical freedom than previously described approaches that require meticulous care in handling of stencil. Thus, this patterning method could be applied in various research fields to pattern proteins or cells on the flexible PDMS substrate

Notations for semi-empirical models of blood sedimentation.

<p>Notations for semi-empirical models of blood sedimentation.</p

Schematic of the experimental setup that was used to obtain optical observations of blood sedimentation.

<p>(A) Sony α900 digital camera with Carl Zeiss Vario-Sonnar lens. (B) Photograph of the micro-hematocrit capillary tubes in 5-place rack. Each capillary tube has an inner diameter of 1.2 mm and a length of 75 mm. (C) Photograph of the Sedi-Rate ESR System inside the light-tight box. Each plastic tube has a sedimentation scale of 200 mm and a bore of 2.55 mm.</p

Calculated erythrocyte settling velocities at different hematocrits.

<p>Calculated erythrocyte settling velocities at different hematocrits.</p

Viscous properties of fluids, densities and velocity of sedimentation.

<p>Viscous properties of fluids, densities and velocity of sedimentation.</p

Influence of dextran and phosphate buffered saline (PBS) on changes in blood conductivity during sedimentation.

<p>The plot presents a comparison of the changes in conductivity for three suspension of erythrocytes in (a) pure plasma, (b) PBS (pH = 7.4, 290 mOsmol/kg), and (c) dextran (425~575 kDa, 1 g/dl) solution in plasma. Each sample had a hematocrit = 45%. The inset presents the details of the initial stage of the change in conductivity.</p

Theoretical model of the suspension of randomly oriented spheroidal particles.

<p>Shell-ellipsoid model for suspension of erythrocytes.</p