Diffusion And Diffusion-based Chemical And Biological Assays Inside And Outside Microfluidic Channels

Diffusion and diffusion-based chemical and biological assays have been studied inside and outside microfluidic channels by using different prototypes of microdevices. Inside microfluidic channels, the propagation of diffusing molecules can be retarded by insertion of micro-chambers, allowing us regulating diffusion limited chemical reactions such as synthesis of ZnO nanocrystals. The diffusion controlled drug delivery has been demonstrated by cell staining assays in microfluidic chambers. Diffusion and cell-based assays could also be studied by designing a new type of microfluidic devices which consists of an array of isolated microchannels plated on a large culture surface, each of them having tiny nozzles for localized but open access drug delivery. As results, assays of both cell staining and drug-induced cell apoptosis showed highly localized drug delivery and fast cell responses in a close proximity of the nozzles. In addition, micro-valves could be integrated into the prototype devices to more precisely control the quantity of diffusing molecules from the nozzles. Considering the very importance of diffusion phenomena at microscales, we believe that our diffusion-based microfluidic devices hold high potential for a large number of applications.