Wafer-Scale Fabrication of Polymer-Based Microdevices via Injection Molding and Photolithographic Micropatterning Protocols

Abstract

Because of their broad applications in biomedical analysis, integrated, polymer-based microdevices incorporating micropatterned metallic and insulating layers are significant in contemporary research. In this study, micropatterns for temperature sensing and microelectrode sets for electroanalysis have been implemented on an injection-molded thin polymer membrane by employing conventional semiconductor processing techniques (i.e., standard photolithographic methods). Cyclic olefin copolymer (COC) is chosen as the polymer substrate because of its high chemical and thermal stability. A COC 5-in. wafer (1-mm thickness) is manufactured using an injection molding method, in which polymer membranes (approximately 130 microm thick and 3 mm x 6 mm in area) are implemented simultaneously in order to reduce local thermal mass around micropatterned heaters and temperature sensors. The highly polished surface (approximately 4 nm within 40 microm x 40 microm area) of the fabricated COC wafer as well as its good resistance to typical process chemicals makes it possible to use the standard photolithographic and etching protocols on the COC wafer. Gold micropatterns with a minimum 5-microm line width are fabricated for making microheaters, temperature sensors, and microelectrodes. An insulating layer of aluminum oxide (Al2O3) is prepared at a COC-endurable low temperature (approximately 120 degrees C) by using atomic layer deposition and micropatterning for the electrode contacts. The fabricated microdevice for heating and temperature sensing shows improved performance of thermal isolation, and microelectrodes display good electrochemical performances for electrochemical sensors. Thus, this novel 5-in. wafer-level microfabrication method is a simple and cost-effective protocol to prepare polymer substrate and demonstrates good potential for application to highly integrated and miniaturized biomedical devices.

Dynamic coating for protein separation in cyclic olefin copolymer microfluidic devices

“…Using COC, Ahn's group developed a biochip for blood typing (Kim et al 2006) while Bhattacharyya and Klapperich (2006) fabricated a device for purification of nucleic acids. Esch et al (2003) studied the effects of different embossing masters on COC microfluidic devices while Lee et al (2005) reported fabrication of COC devices in the wafer scale. Craighead's group employed COC chips for protein separation and for interfacing with a mass spectrometer Yang et al 2005) while Kirby et al studied the zeta potential of COC microchannels (Mela et al 2005).…”

Cyclic olefin polymers: emerging materials for lab-on-a-chip applications

“…In the experiments, performed by Lee et al (2005), it was noticed that the gold adhesion to the COP substrate was better than when using a typical pre-adhesive layer (usually Cr or Ti). The lack of an adhesion layer is an advantage especially when fabricating microelectrodes, since it eliminates the need of a passivation layer to protect the edges of the electrode that expose the adhesion layer to the solution.…”

Potentiometric analytical microsystem based on the integration of a gas-diffusion step for on-line ammonium determination in water recycling processes in manned space missions

“…Whereas, low temperature co-fired ceramics (LTCC) are incompatible with the integration of polymeric membranes due to the high temperatures reached during sintering process [14]. In addition, polymer technology has other important advantages like an easy microfabrication of hermetically sealed three dimensional structures, chemical inertia against most acids and alkalis, the possibility to integrate conductive tracks and a good mechanical resistance [15][16][17][18]. In this way, these advantages allow the possibility to obtain robust and low cost microanalyzers of rapid prototyping and with low sample and reagents consumption by means of the monolithic integration of all components of the analytical process (pretreatment stages, microfluidics and detection system) on a single substrate [19].…”