Figure 3.

(a) Burst pressure measured across 10 $\mathrm{\mu }$m-thick in situ barriers printed on COP surfaces treated with varying BP concentrations and UV irradiation time. (b) Variation in burst pressure for different barrier thicknesses (1.0 wt% BP, 5 min UV) (c) Impact of surface topography on burst pressure using surfaces with trapezoidal cross section grooves (10 $\mathrm{\mu }$m-thick barriers, 1.0 wt% BP, 5 min UV). (d) Images of the grooved COP microchannels in (c), with selected geometries for groove pitch (P), spacing (S), and depth (D). Base angle of the trapezoidal cross section is fixed at 70${}^{\circ }$.