Research On Fabrication Of Magnetic Controllable Micromachine In Microfluidic Chips

In recent years,microfluidic chips have attracted more and more attention from researchers around the world due to their important applications in the fields of chemistry,physics,biology and medicine.Particles and cells separation based on microfluidic chips,combining the benefits of continuous operation and low cost of reagents and analysis time,has attracted great attention due to their broad applications in chemistry,biology,medicine,and pharmaceutics.However,most methods use motionless micro-nanostructures,which typically require complex fluid field design and can only irreversibly intercept particles above specific size through the structures.Thus,particle separation in mixed liquid flow with a high success rate and simple mode of controllable operation still remains to be a challenge.On the other hand,micromechanics which is widely used for drug delivery,biosensing,sewage treatment,material assembly,and nanoscale imaging has been thoroughly studied.At present,the common micromechanical driving methods include chemical force driving,magnetic driving,optical driving,electric driving.And common processing methods for manufacturing micromechanics include photolithography,electrochemical deposition,chemical synthesis,reactive ion etching.And particularly,two-photon polymerization processing technology can flexibly process these micro-nano-scale devices as a micro-scale three-dimensional printing technology.Moreover,the micro device achieves a more flexible function by functionally doping the photoresist.This work presents a smart turbine-like multifunctional microfilter with magnetic field dependent rotary property,which is aimed at remote controllable separating of specific micron-sized particles.It can be integrated in a three-dimensional microfluid chip by femtosecond laser two-photon polymerization of stable,isotropic and homogeneous ferrofluids composed of oily photoresist and surface modified Fe3O4 nanoparticles.The microfilter is designed to be a perforated sheet with customized-sized holes fixed on an integrated stator with bearing and spindle.The device can be manipulated to rotate an arbitrary angle by varying the external magnetic field,thus achieving the interception and releasing of specific size particles.As a verification of microfilter functions,2.5?m and 8?m particles are time sharing separated from a mix liquid stream inside a microfluidic chip.The magnetic controlled microfiltering device proposed here proved to be both easy operation and high performance in microfluidic systems,which has promising application in microparticle purification,CTCs separation,blood cells sorting,and other biomedical research.