Review JoëlRossier 1 FrédéricReymond 2 PhilippeE.Michel 2 1 Laboratoire d’Electrochimie, Département de Chimie, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland 2 DiagnoSwiss S.A., Monthey, Switzerland Polymermicrofluidicchipsforelectrochemicaland biochemical analyses Our recent developments concerning the fabrication of polymer microchips and their applications for biochemical analyses are reviewed. We first describe two methods of fabrication of polymer microfluidic chips, namely UV-laser photoablation and plasma etching that are well suited for the prototyping and mass fabrication of microchannel networks with integrated microelectrodes. These microanalytical systems can be coupled with various detection means including mass spectrometry, and their applica- tions in capillary electrophoresis are presented here. We also present how UV laser photoablation can be used for the patterning of biomolecules on polymer surfaces for generating two-dimensional arrays of microspots to carry out affinity assays. Finally, the use of the microchips for the development of fast affinity and immunological assays with electrochemical detection is presented, demonstrating the potential of these poly- mer microchips for medical diagnostics and drug discovery. Keywords: Affinity assay / Capillary electrophoresis / Disposable plastic microchips / Immuno- assay / Plasma etching / Review / UV laser photoablation EL 4811 Contents 1 Introduction ........................... 858 2 Fabrication of polymer microchips ......... 859 2.1 Polymer materials ...................... 859 2.2 Prototyping by UV-laser photoablation ...... 860 2.3 Mass production by plasma etching ........ 860 2.4 Sealing ............................... 861 2.4.1 Lamination ............................ 861 2.4.2 Plasma bonding ........................ 861 3 Electrokinetically driven microdevices ...... 862 3.1 Electroosmosis in microchips ............. 862 3.2 Electrophoretic separations with different detection means ....................... 862 4 Affinity protein assays ................... 863 4.1 Protein patterning on photoablated surface . . 863 4.2 ELISA and affinity assay procedures ....... 864 4.3 Electrochemical detection in microchannel . . 864 4.4 Fast affinity assays with electrochemical detection .............................. 865 5 References ............................ 866 1 Introduction Over the last years, the miniaturization of biochemical analytical tools and the development of miniaturized apparatus also called micro-total analysis systems (m-TAS) has become an expending field [1]. Indeed, such devices allow decreasing both the consumption of analytes and the duration of analyses [2]. This is of particular interest for the new life science developments such as genetic analysis [3] or high-throughput screening for drug discov- ery. Indeed, in these applications, the number of assays to perform has tremendously increased, and the reason for decreasing the consumption of analytes is to reduce the cost but also to limit sample handling and the produc- tion of wastes. Moreover, in medical diagnostics, it may be necessary to analyze extremely small volumes and/or to get rapid results. Medical diagnostics also requires dis- posable systems in order to avoid any risk of cross con- tamination. Therefore, to reach the competitive world of analysis and diagnostics, miniaturized systems have to be fabricated in mass and at low cost. One way to enable the technology transfer from the early stage of silicon or glass prototypes is the fabrication of microchips in polymeric substrates [4]. Polymer microstructures can be produced in high volumes with simple technologies such as imprinting [5], injection moulding [6] or polydi- methylsiloxane (PDMS) casting [7]. The facilitated sealing procedures such as temperature annealing bonding, lami- nation [8] or plasma oxidation [9] enable an efficient bond- ing with a high yield. Correspondence: Dr. Joël Rossier, Laboratoire d’Electrochimie, Département de Chimie, Ecole Polytechnique Fédérale de Lau- sanne, CH-1015 Lausanne, Switzerland E-mail: joel.rossier@epfl.ch Fax: 141-21-693-36 67 Abbreviations: ALP , alkaline phosphatase; PE, polyethylene; PET , polyethylene terephthalate; SEM, scanning electron micro- scopy; TEA, tetraethylammonium; TMA, tetramethylammonium 858 Electrophoresis 2002, 23, 858–867 ª WILEY-VCH Verlag GmbH, 69451 Weinheim, 2002 0173-0835/02/0603–858 $17.50+.50/0