Generation of two-dimensional concentration-gradient droplet arrays on a two-layer chip for screening of protein crystallization conditions

We developed a two-layer microfluidic chip for the generation of two-dimensional concentration-gradient droplet arrays. All of the channels, including a concentration-gradient formation channel network, an oil phase channel network, and droplet generators, were ingeniously arranged on a single polydimethylsiloxane (PDMS) substrate, which facilitates the fabrication of the chip. Ninety-six lines of subnanoliter droplets with concentration...