We report an initial study on hot roller embossing as a potential process for the mass production of polymer based microfluidic chips. Measurements conducted on 100 lm features showed that the lateral dimensions could be replicated to within 2% tolerance, while over 85% of mould depth was embossed. Feature sizes down to 50 lm and feature depths up to 30 lm had been achieved. Results revealed that the embossing depth increased with an increase in the nip force or a decrease in the rolling speed. There was an optimum temperature for achieving a high embossing depth; this was due to the reflow effect seen at higher temperatures. One observation included an asymmetric pile up of polymer material outside the embossed regions as a result of the orientation of the microchannel with respect to the rolling direction. This directional effect could be due to the dynamics of the roller setup configuration.

We present a thermally activated solvent bonding technique for the formation of embedded microstructures in polymer. It is based on the temperature dependent solubility of polymer in a liquid that is not a solvent at room temperature. With thermal activation, the liquid is transformed into a solvent of the polymer, creating a bonding capability through segmental or chain interdiffusion at the bonding interface. The technique has advantages over the more commonly used thermal bonding due to its much lower operation temperature (30°C lower than the material's T g ), lower load, as well as shorter time. Lap shear test indicated bonding shear strength of up to 2.9 MPa. Leak test based on the bubble emission technique showed that the bonded microfluidic device can withstand at least six bars (87 psi) of internal pressure (gauge) in the microchannel. This technique can be applied to other systems of polymer and solvent.

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We report on the development of process capabilities for a polymer-based, multi-layer microelectrofluidic platform, namely: the hot embossing process, metallization on polymer and polymer bonding. Hot embossing experiments were conducted to look at the effects of load applied, embossing temperature and embossing time on the fidelity of line arrays representing micro channels. The results revealed that the embossing temperature was a more sensitive parameter than the others due to its large effect on the polymer material's viscoelastic properties. Dynamic mechanical analysis (DMA) conducted on polymethyl methacrylate (PMMA) revealed a steep glass transition over a 20°C range, with the material losing more than 95% of its storage modulus. The data explained the hot embossing results, which showed large changes in the embossed channel dimensions when the temperature was within the glass transition range. It was demonstrated that the micro-printing of silver epoxy was a possible low-cost technique in the mass production of disposable lab chips. An interconnecting, three-dimensional network of electrical traces was fabricated, as well as a microfluidic device with interconnecting, three-dimensional network of micro channels.

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