Method of mould alignment for double-sided hot embossing of microfluidic devices using kinematic constraints

Demand has increased for the double-sided moulding of microfluidic devices for a series of biochemical analyses. Accurate alignment of mould inserts is a critical aspect to transfer doubled-sided patterns on the top and bottom surfaces of a moulded part. A method of mould alignment was studied for double-sided hot embossing of polymer microfluidic devices. An alignment method was designed using kinematic constraints, and a set of three locating pins. To validate the alignment method, two brass mould inserts with fluidic reservoirs were used for the double-sided moulding of prototype microfluidic devices. The kinematic constraints were used to align the mould inserts with each other on the hot embossing machine. The misalignment of double-sided features on the moulded parts was measured using a measuring microscope. The X- and Y-magnitudes of the mismatches ranged from -28 to 118 μm along the X-axis of the moulded parts. The X- and Y-magnitudes of the mismatches along the Y-axis of the moulded parts varied from -38 to 141 μm. The results of the experiments showed that the mould alignment using kinematic constraints is applicable to the fabrication of double-sided patterns for microfluidic devices.