Assembly Methods And Devices For Micro-nanofluidic Chips

Microfluidic chip has been widely used in rapid, high-throughput and low-consumption analysis of biochemical samples and it has broad application prospects in the fields of biomedicine, etc. Since the feature size of the nanochannel is on the order of macromolecules, microfluidic chip with nanochannels, often called micro-nanofluidic chip, is quite suitable to the study of biomacromolecule, such as single molecule detection, segregation analysis, DNA sequencing, protein-enrichment, etc. Our group has developed a low-cost and flexible method for the fabrication of separating micro-nanofluidic chip. The micro-nanofluidic chip is composed of two plates in which there are microchannels and nanochannels, respectively. Since the channels are formed, the nanochannels and microchannels need to be assembled together by microassembly methods.Aimed to assembly demands and operation requirements for separating micro-nanofluidic chips, considering reducing assembly stress, the paper has put forward a rotating-then-pushing (RP) method based on studying the problems of micro-nano structure observation, feed adjustment and assembly stress. The RP device is developed, which consists of micro-optical observation unit, rotating-fixed unit, etc. This device includes inverted microscope which can observe micro-nano structures, magnetic stripe which can fix bottom plate, and high-precision mobile platform which can push top plate. From the consideration of handling with care, a picking up-then-placing down (PP) method is put forward. The PP device composed of micro-optical observation unit, mechanical feeding unit and picking up-and-placing down operation unit et al, is developed. This device observes micro-nano structure by dark-field illumination unit, adjusts angles and positions between bottom and top plates by high-precision mobile platform, and accomplishes picking and placing operation by vacuum suction method.With the two assembly methods and devices, assembly experiments are carried out in five species of micro-nanofluidic chips, including glass, PDMS-glass, ultra thin glass-PDMS, etc. Then ionic enrichment and near-field optical experiments are conducted on completed micro-nanofluidic chips. Experimental results demonstrate that the RP and PP methods and devices can realize the alignment of two-layer micro-nanofluidic chips, and they are suitable to multilayer ones as well. The microassembly methods with these devices have the advantages of low cost, flexibility and interchangeability.