Microfluidic Chips Based On The Permeability Of Steel Pneumatic Suction Mold Release Systems Experimental Research

According to the shortage of non-destructive demolding and chip bonding in current microfluidic chip injection molding technology, unable to develop the advantage of short molding cycle, high automation, ease of molding complex 3D structure and integration manufacturing, automatic non-destructive demolding technology for microfluidic chip In-Mold-Bonding(IMB) was studied. Based on the special demand of IMB technology, breathable steel, which was one kind of porous material, was introduced into the demolding process of microfluidic chip, an innovate method of air induced demolding using breathable steel was developed, and feasibility was argumented both in surface roughness and vacuum, ejection force, which provided data and theory support for exploring a new demolding method in micro injection molding.Considering the demand of microfluidic chip sucking and demolding system and performance of different porous material, breathable steel was selected for the demolding system. Machining method and surface roughness of it were studied. Based on research results above, according to actual shape, size and structure of microfluidic chip, one experiment device of microfluidic chip sucking and demolding system which could transplant to inside the mold was self developed, which provided a experiment platform for testing the processing parameters and permeability of breathable steel.The vacuum and ejection force of microfluidic chip sucking and demolding system were studied experimentally, response rule of pressure and vacuum to time was revealed. The results showed that it could reach the vacuum and ejection force in short time because of its own air permeasibility of breathable steel, the system could realize function of vacuum and demolding, the decrease of vacuum and the increase of pressure could shorten time needed for absorbing and ejecting chip, low vacuum and high pressure were recommended considering the molding cycle.Permeability of breathable steel was investigated experimentally considering the compressibility of fluids, the results showed that, with the increase of pressure, flow regime of gas in breathable steel was transformed from Darcy flow to non-Darcy flow, permeability coefficient and inertia coefficient were calculated respectively, and the flow equations of the two flow regimes above were obtained, flow law of different flow regimes in breathable steel was revealed.