Active Multilayer Centrifugal Microfluidic Chip And Its Applications

With the increasing demand for better disease treatment and medical care,especially for the growing demand of point of care testing(POC T),a "lab-on-a-chip"(LOC)or microfluidics approach for bioassay is booming in recent years.In particular,centrifugal microfluidic CD or lab-on-a-disc(LOAD)platforms have made great progress in the past decades.A centrifugal microfluidic platform pumps liquid under the forces created by simple and compact motor,which requires no external interconnects to induce fluid movement.Owing to its advantages over bulkier traditional fluidic platforms such as full automation,portability,and low fabrication cost,the centrifugal microfluidic platform has made a big difference in POCT,clinical chemistry,immunodiagnostics,protein analysis,cell handling,food safety and so on.However,it is difficult to integrate complex biomedical medical applications on the existing centrifugal microfluidic platforms.In order to solve these problems,the electricity is introduced into the platform,the wireless power supply module and the wireless communication module are integrated on the centrifugal force microfluidic platform,and an active centrifugal force microfluidic platform is built.Based on our active centrifugal platform,we have introduced heating resistors in PCB layer to melt and open the paraffin wax valves in microfluidic layer with program control at user's disposal.Besides,we have designed several universal structures including liquid sequential loading and switching of liquid based on paraffin wax valves,which may implement more functions.We have presented a design of multilayer complex chip on the active centrifugal platform,which utilizes on-board control of wax valve on a disc.And we have realized several applications on the active multilayer centrifugal microfluidic chip.In the aspect of DNA extraction,plasmid DNA extraction and whole blood DNA extraction process have been carried out on the chip,each experiment has been conducted in tube and on chip.The 260/280 absorbance ratios of DNA from chip were between 1.8 to 2.0,the 260/230 absorbance ratios were all greater than 2.0,the concentration of DNA extracted were more than 30 ng/?L.These results proved that DNA extracted on chip was of high purity free from protein contamination and it was sufficient for normal Sanger sequencing.Therefore,our chip method was as efficient as the standard technique.We can get a deeper judgment of target gene based on the molecular size by real-time quantitative polymerase chain reaction(qPCR)on the extracted plasmid DNA in tube and on chip.The six dissociation curves of DNA extracted from both chip and tube were almost coincided.Besides,their melting temperatures were the same that were near 89-90?.Therefore,we can get the conclusion that the plasmid DNA extracted from our chip was of high quality.In the aspect of exosomes,the processes of exosomes isolation and fluorescence detection of exosomes have been designed and carried out on the chip.The design of the exosomes isolation chip not only utilized the wax valves and universal structures including liquid sequential loading and switching of liquid flow,but also used two integrated filters for exosomes isolation instead of ultracentrifugation(UC).Besides,the chip was washed by a plasma cleaner for chip fabrication.After isolating exosomes,exosomes were bound by aptamers for fluorescence detection on chip.It is hoped that based on our active centrifugal microfluidics platform and the paraffin wax valves,more multilayer chips will be designed to make more contributions to biomedicine by implementing more biological applications.