Abstract

Concentration gradient is an important topic in the field of antimicrobial susceptibility studies as well as biological and drug research. To test the efficacy of certain chemical substance on biological samples, one usually exposes the sample to a large range of concentration gradients and looks for the subsequent responses. Here, we present a 3-dimensional centrifugal microfluidic platform for the generation of discrete concentration gradients in a series of fluidic chambers, which may then be used for studying biological responses. The microfluidic chip consists of two layers. Firstly, under the actuation of a centrifugal force field, an aqueous drug stored in the first layer is distributed into 16 metering chambers with linearly increasing volumes. Meanwhile, DI water in a second layer is also distributed into 16 metering chambers with linearly decreasing volumes. As we increase the centrifugal field, the different volumes of DI water and drug stored in their respective metering chambers will flow into the mixing chambers, hence producing the concentration gradients as desired. Absorbance data obtained from a red dye confirms that our concentration gradient generator has high repeatability. An immediate application of this device high-throughput assessment of minimum inhibitory concentration of antibiotics against bacteria, which may help to prevent the spread of drug resistance.

© 2017 Optical Society of America