Process Issues for a Multi-Layer Microelectrofluidic Platform

TL;DR

This paper explores process techniques for a multi-layer polymer microelectrofluidic platform, focusing on hot embossing, metallization, and bonding, with experiments revealing key parameters affecting microchannel fidelity and device fabrication.

Contribution

It introduces optimized process parameters for hot embossing and demonstrates low-cost micro-printing of electrical traces in multi-layer polymer devices.

Findings

Embossing temperature significantly affects microchannel dimensions.

DMA data correlates glass transition with embossing fidelity.

Successful fabrication of multi-layer PMMA devices with microfluidic channels.

Abstract

We report on the development of some 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 is a more sensitive parameter than the others due to its large effect on the polymer material's viscoelastic properties. Dynamic mechanical analysis (DMA) on polymethyl methacrylate (PMMA) revealed a steep glass transition over a 20 oC range, with the material losing more than 95 % of its storage modulus. The data explained the hot embossing results which showed large change in the embossed channel dimensions when the temperature is within the glass transition range. It was demonstrated that the micro-printing of silver epoxy is a possible low-cost technique in the mass production of disposable lab chips. An interconnecting network of electrical traces was fabricated in the form of a four-layer PMMA-based device. A four PMMA layer device with interconnecting microfluidic channels was also fabricated and tested.