Fabrication And Application Of Grid-controlled Nanofluidic Devices Based On Nanoimprinting

In recent years,micro-nano fluidic chips with micro-nano structures as core components have been widely used in the fields of biology,chemistry,and medical treatment due to their miniaturization and in-situ driving.The contact between the solid nanochannel wall material and the solution generates surface charges,thereby forming an electric double layer.Because the Debye length is similar to the channel size at the nanometer scale,a unique ion transport phenomenon will occur.The electric double layer produced by ordinary solid-state nanochannels is determined by the surface properties,and it is difficult to change the device once it is manufactured.By fabricating a gate electrode on the device and applying a voltage,the internal charge arrangement of the nanochannel can be affected,the electroosmotic flow control performance of the device can be affected,and the field effect control can be performed.First,the application directions of concentration-driven and electrochemical-based nanodevices in micro-nanofluidic devices are introduced.The planar array-based nanogrooves are easy to construct gate-controlled nanofluidic devices.Then it introduces the research foundation of nanofluidic devices based on gate voltage regulation and the fabrication process plan of integrated gated electrode micro-nanofluidic devices.The research content of fabricating gate-controlled nano-control devices based on nano-imprinting process and conducting control tests are put forward.Secondly,according to the control principle model of the gate-controlled nanofluidic device,the geometric parameters of the device such as the height of the nanochannel,the length of the nanochannel,and the thickness of the dielectric layer will affect the control performance.The exploration of control performance involves the coupling of multiple physical fields,such as electric field,ion distribution,and fluid flow,and is usually solved by numerical methods.Taking the dimensions of each part of the gate-controlled nanofluidic chip as the research goal,a COMSOL simulation model was established to explore the control performance of nanochannel devices under different sizes,and to optimize the parameters for the production of gate-controlled nanofluidic devices with better control performance as the guide.Based on the simulation results again,the structure design and process plan of the gate-controlled nanofluidic device are determined.The device structure design and the process plan influence each other.The manufacturing process uses the sputtering lift-off process to fabricate the metal gate,the nanoimprint process to fabricate the core array nano-channel part of the gate-controlled nanofluidic device,and the magnetron sputtering process makes the bonding bond.Floor.Use SU-8 glue to make a mold for pouring PDMS micron fluid channels.After oxygen plasma treatment,the above two parts are bonded to seal the trench to form a grid-controlled micro-nano fluidic device integrated with micro-channels.Finally,a grid-controlled regulation test was performed.A DC power supply and a picoammeter were used to build a test platform.The conductance changes without gate voltage were tested in different concentrations of KCl solution,and it was verified that the nanochannel part of the grid-controlled nanofluidic device could work normally.The control curves of ion current under different grid voltages were tested,and the comparison of simulation data proved that the grid voltage can regulate the ion current.Two proteins with similar isoelectric points and different molecular sizes are selected to characterize the ability of gate voltage to regulate the transport of macromolecules by measuring ion current,which provides an experimental basis for the separation of biomolecules in gate-controlled fluidic devices.