The Precision Replication Of Metallic Glass Mould For The Biochip Application

Microfluidic chip is one of the most studied in biochips, which has arousedincreasing interest in biological and medical sciences. In the progress of this technology,polymers have been proven to be the most suitable substrate materials for microfluidicdevices. Such polymer devices are often fabricated by replicating a master mould throughhot embossing, casting or injection moulding methods. Currently, various materials suchas electroformed nickel, silicon, SU-8and anodic aluminum oxide （AAO） have been usedfor the thermo-mechanical replication of polymers. However, there were some problems.For example, the production process is time consuming, brittle, low life. Bulk metallicglass has superior properties, such as high strength and hardness, high Young’s modulus,high corrosion and wears resistance. If the bulk amorphous alloys as a master mold, itwill be one of the most important ways to solve these problems.In this work, we design a microchannel pattern for the application of biochip, whichhas been obtained by dry etching. The Zr₃₅Ti₃₀Be_26.75Cu_8.25bulk metallic glass, which hasbeen prepared by copper mold casting, has been hot-embossed on the silicon mastermould under a appropriate condition （temperature:370℃、strain rate:1×10-3s-1）. The crosssection of the hot-embossed topography was observed by scanning electron microscopy（SEM）, and the results revealed that there is no discernible gap at the interface betweenthe silicon and the metallic glass. The simulations were performed using commercialsoftware DEFORM3D to reveal the micro-scale hot-embossing process. Thetheoretically forming pressure and the maximum filling length were calculated accordingto the Hagen-Poiseuille law. Both experimental and theoretical results demonstrated thatthe microchannel features can be accurately replicated under the hot-embossed conditionswith a low flow stress.As we know that both temperature and strain rate significantly affect the flowcharacteristics of the material in the hot-embossing process. So, the uniaxial compressiondeformation behaviors of Zr₃₅Ti₃₀Be_26.75Cu_8.25bulk metallic glass under different temperature and strain rates have been studied. The result show that there exists flowcharacteristics change from Newtonian flow to Non-Newtonian flow at a certaintemperature with the strain rate increase. The Zr₃₅Ti₃₀Be_26.75Cu_8.25bulk metallic glassmicrochannel mould has been fabricated through hot embossing under the correspondingtemperature and strain rates. The simulations were performed using commercial softwareDEFORM3D to reveal the micro-scale hot-embossing process at different rheologicalstate. Both experimental and simulation results demonstrated that BMGs have bettermicro-formability in Newtonian flow.Finally, the effect of holding pressure and constraints to the formability in thelarge-size micro-array hot-embossing has been studied in this thesis. It has been foundthat the large-size micro-array can be fabricated when compelled after increasing holdingpressure and constraints.