Physical modelling, numerical simulation and experimental investigation of microfluidic devices with amorphous thermoplastic polymers using a hot embossing process

This paper studies the hot embossing process applied to amorphous thermoplastic polymers, including the characterization and identification of the polymers' viscoelastic behaviour, numerical simulation of the filling stage in the micro hot embossing process and experimental elaboration of microfluidic devices prepared by a hot embossing process. Static compression creep tests have been carried out to investigate the selected polymers' viscoelastic properties. The Generalized Maxwell model has been proposed to describe the relaxation modulus of polymers PS, PMMA and PC, and good agreement has been observed. The numerical simulation of the hot embossing process in 3D has been achieved by taking into account the viscoelastic behaviour of the polymers. A new complete micro compression moulding tool, including a heating system, a cooling system and a vacuum system, has been developed in our research group. Microfluidic devices with cavity dimensions equal to approximately 200 μm, 100 μm and 50 μm in PS, PMMA and PC plate (thickness equal to 2 mm) have been elaborated by the hot embossing process. The effects of the processing parameters, such as the compressive gap imposed, the compression temperature, the embossed material and the die cavity dimensions, on the replication accuracy of the hot embossing process have been investigated. The comparison between the numerical simulation and the experiments shows proper agreement for the prediction of the polymer substrate deformation in the replication of a microfluidic device using the hot embossing process. The developed hot embossing experimental system exhibits a low cost and short production cycle for the elaboration of microfluidic devices based on amorphous thermoplastic polymers, which provides the possibility of mass production for the elaboration of microfluidic devices.