(a) Microfluidic chip with cell sieves for cell trapping. Reprinted with permission from Wang et al., Lab Chip 7, 740 (2007). Copyright 2007 The Royal Society of Chemistry. (b) Microfluidic device for drug metabolism and cytotoxicity assay. Reprinted with permission from Mao et al., Lab Chip 12, 219 (2012). Copyright 2012 The Royal Society of Chemistry. (c) Microfluidic chip used for parallel microdroplets (PμD) technology. Reprinted with permission from Damean et al., Lab Chip 9, 1707 (2009). Copyright 2009 The Royal Society of Chemistry.