Diagram of points on the slide were thickness measurements were taken.

<p>The thickness of the film on each slide was calculated as the mean of the thicknesses of points A–D. The profile was generated by measuring the thickness at points spaced 1 mm apart (or less near the edge) along the profile line.</p

Thickness of the 100% PDMS film under two different spin speeds as a function of spin time.

<p>Each data point is the average of the mean thickness of three slides. The error bar is the 95% confidence interval. Each curve is a plot of Equation (2) for the given speed.</p

Control of cell distribution on MOCCA.

<p>(a) The average cell number (λ) per droplet versus experimental bulk cell concentrations. (b–e) Cell distributions of four cell concentrations in bulk medium. Dark bars: experimental results; light bars: fit Poisson distribution.</p

MOCCA generation visualized using an optical microscope.

<p>(a) Mineral oil is dispensed around the cell medium (top-center of figure), forcing cell medium to move up; (b–c) Oil does not repel the medium that occupies the hydrophilic areas; (d) When the bulk cell medium has fully retreated, an array of medium droplets is separated by oil. Scale bar in (d) equals 400 um and applies to all pictures.</p

Profiles of five PDMS membranes spun for 5 min on glass.

<p>Each profile is a single sample, ending in the edge bead. The profiles in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004572#pone-0004572-g004" target="_blank">Figure 4</a> were measured from the center point of the slide to the edge along the long axis as indicated by the “Profile line” in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004572#pone-0004572-g005" target="_blank">Figure 5</a>.</p

Thickness of the PDMS film under various concentrations (by weight) of PDMS in tert-butyl alcohol (TBA) as a function of spin speed.

<p>Each data point is the average of the mean thickness of three slides. Each slide was spun for 5 min. The error bar is the 95% confidence interval. The line is the least-squares fit of the data. The density of TBA is 0.775 g/mL at 25°C.</p

MOCCA formation procedure.

<p>(a) Flood the μPLAT-patterned cover glass with cell medium; (b) Flood the cover glass using mineral oil to repel cell medium. Small volumes of medium still occupy hydrophilic disks on the treated surface; (c) After completion, some droplets in the array contain cells.</p

Constants in the mathematical relationship between spin speed and PDMS film thickness.

<p>The parameters α and <i>k</i> are derived from the least-squares fit of the data summarized in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004572#pone-0004572-g002" target="_blank">Figure 2</a> using Equation 1 where angular velocity is in RPM and thickness is in µm.</p

Hydrophilic patterning process.

<p>(a) Adhere a mask to a glass cover slip; (b) Expose to air plasma; (c) Remove the mask, leaving a hydrophilic disk array on the surface.</p

Result comparison of microscopy techniques between using conventional microscope slide with cover glass and MOCCA.

<p>Result comparison of microscopy techniques between using conventional microscope slide with cover glass and MOCCA.</p