Controlled mechanical fracture for fabricating microchannels with various size gradients

摘要: We present a simple method to generate cracks with controllable size (depth and width) space gradients using deep surface oxidation anisotropic mechanical stretching. To thick layer (<∼7 µm), polydimethylsiloxane (PDMS) slab of uniform or varying thickness was exposed UV/ozone for less than 30 min in the UV-C wavelength including wavelengths 185 254 nm. Subsequently, PDMS wrapped on cylindrical support (radius: 11 mm) apply bending strain (<21%), resulting equally separated, over large area. By modulating initial depth applied stress, sizes spaces were formed single slab. Furthermore, multiple, sequential generated by increasing step-wise fashion multi-directional applying an orientation angle. Finally, space-varying between two adjacent channels interconnected format selective masking irreversible bonding.