Fabrication Of Micro-nanofluidic Devices Based On Sacrificial Layer

Micro-nanofluidic chips and nanochannel devices can be applied to molecular-level researches in many fields,such as biomedicine,physics and chemistry.However,it has high limitations in fabricating nanochannel with super-high requirements for equipments,materials,environment and cost,especially in fabricating the nanochannel which is less than 50 nm in one dimemsion or two dimensions.There lacks good conditions to fabricate micro-nanofluidic chips and nanochannel devices in general universitis,research institutes and enterprises.This mainly explains why the researches of nanofluidics are so far less popular than microfluidics and why the development of nanofluidics is restricted.Here we developed a simple and inexpensive approach to fabricate a nanochannel device with a glass/thin epoxy resin layer/glass structure.The grooves were engraved using a UV laser on an aluminum sacrificial layer on the substrate glass,and epoxy resin was coated on the substrate and stuffed fully into the grooves.Another glass plate with holes for fluidic inlets and outlets was bonded on the top of the resin layer.The nanochannels were formed by etching thin sacrificial layers electrochemically.Meanwhile,the microstructures of the fluidic outlets and inlets could be fabricated simultaneously to the nanochannel formation.The micro-nanofluidic chips have been fabricated,which could integrate nanochannels with depth of less than 20 nm and microchannels with depth of more than 3?m,and withstand high pressure of 12 MPa.Compared with other fabrication methods of nanochannel,our method has more advantages: it can fabricate full transparency high-strength micro-nanofluidic chips and nanochannel devices by common equipments under common environment,which is extremely simple,low costly and requires less profound knowledge and experiences.It can popularize the researchs of nanochannels and applications of nanochannel in general universities,research institutes,and speed up the research of micro-nanofluidics.Researches and the applications of nanochannel are depends on electric field driving(electroosmotic flow,etc.)for driving nanofluides.However,the electric field driving method is not suitable for all kinds of the nanofluids,which could affect the biochemical reactions,and lead to electrolytic reactions.The micro-pumps applied in microfluidics are limited by low pressure and low control presion,thus are difficult to drive nanofluids in nanochannels with super-high hydraulic resistance(MPa scale)and super small volume(fL scale).Here we have developed a nanofluid-high-pressure pump based on high pressure gas generated by electrolysis,and a nanofluidic application system comprised with nanochannel device.The fluid in nanochannel was driven by high pressure gas which was controlled by closed-loop computer system(consisted of MCU and PC)and high speed precise pressure sensor which collected pressure data to the computer.The control precision of this micro pump mainly depends on the response speed,precision and stability of the pressure sensor,and the maximum output pressure generated by the micro pump mainly depends on the structural strength of the pump body and pressure sensor.At present,more than 200 ATM output pressure has been achieved and used for the control of the nanofluid.This high pressure pump system was proposed and realized for the first time in the field of nanofluidics and microfluidics,and its application could be extended to other fluid control fields,such as high-performance liquid chromatography.Finally,the micro-nanofluidic chips and nanofluid-high-pressure pump have been tested.The evaporation of nanofluid water in the nanochannel and the flow rates of the capillary diffusion rates of nanofluid water in the nanochannel have been measured.The electroosmotic flow/electrophoresis of fluorescein sodium aqueous solution and DNA aqueous solution in nanochannel have been studies.The ohmic-limiting-overlimiting current curve of nanochannel have been detected.The flow of oil/water/gas mixtures in the nanochannel have been achieved and driven by high pressure pump.