Poly(ethylene glycol) (PEG) microwells in microfluidics: Fabrication methods and applications

Immobilization of bioanalytes (e.g., protein, lipid membrane, and cells) within a microfludic channel is a useful strategy in diverse biological analysis including biosensor, diagnosis, and biochemical reactions. Such microfluidic systems can offer miniaturized platforms with distinct advantages such as reduced use of samples or reagents and increased resolution. In particular, polymeric microfluidic devices (e.g., polydimethylsiloxane (PDMS)) bound to a substrate have been widely used. However the non-specific adsorption of bioanalytes is serious problem for microfluidic biological assays, especially for dilute samples. To overcome such limitations, a simple and widely applicable microfluidic channels combined with polyethylene glycol (PEG) microwells have been developed. In this review, we summarize the methods and application of PEG microwells with a particular emphasis on integrated microfluidic systems. The assembly between PEG microwell and microchannel enables precise delivery and manipulation of the biosamples, leading to development of miniaturized diagnostic assays, microreactors, and multiple screening platforms for tissue engineering and cell biology.