UV curing of low molecular weight polyethylene glycol (PEG) monomers such as PEG dimethacrylate and PEG diacrylate (PEG-DA) on a silicon mold with the microchannels arrays or pillars can be performed to fabricate PEG microchannels and porous PEG membranes, respectively (Figure ) . During casting, a PET layer modified with urethane groups could be placed on top as the supporting layer to adhere to the acrylate-containing PEG monomers. As the supporting layer, it is also possible to use glass slides treated with phosphoric acrylate or acrylic acid dissolved in propylene glycol monomethyl ether acetate, to bind to PEG . In another study, Liu et al. first made an enclosed mold comprising a bottom silicon layer with the channel's array, middle PDMS spacers, and a top glass slide . Afterwards, PEG-functionalized monomer solution containing 85% PEG-DA, 12% poly(ethylene glycol) methyl ether methacrylate (PEG-MEMA), 3% methyl methacrylate, and 2,2′-dimethoxy-2-phenylacetophenone (DMPA) was injected onto the mold and cured for 16 s under UV. Tian et al. also UV cured PEG-DA on a PDMS mold using 1% photoinitiator Irgacure 2959 to form the microfluidic design . UV lithography has also been used to create micro-geometries in PMMA substrates . This process involves UV exposure of the PMMA substrate with a photoresist through a mask and development of the photoresist, coating a thick layer of X-ray absorber to the exposed areas to create an X-ray mask, emitting X-ray to form the desired channels, and finally removing the X-ray mask form the substrate.