Sensors and Actuators A 223 (2015) 76–83 Contents lists available at ScienceDirect Sensors and Actuators A: Physical j ourna l ho me page: www.elsevier.com/locate/sna Direct assembly of cyclic oleﬁn copolymer microﬂuidic devices helped by dry photoresist Lamia El Fissi a,∗ , Denis Vandormael b , Laurent A. Francis a a ICTEAM Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium b SIRRIS – Liege Science Park, Seraing, Belgium a r t i c l e i n f o Article history: Received 15 July 2014 Received in revised form 5 December 2014 Accepted 11 December 2014 Available online 19 December 2014 Keywords: Cyclic oleﬁn copolymer Adhesive bonding ORDYL negative dry ﬁlm photo resist Oxygen plasma treatment a b s t r a c t A generic method for rapid, reproducible, and robust selective bonding of microﬂuidic chips made of Cyclic Oleﬁn Copolymer (COC) has been developed and optimized. In this work we propose an adhesive bonding technique using ORDYL negative dry ﬁlm photo-resist as glue to perform the packaging of COC micro- patterned structures. The ORDYL resist is qualiﬁed in terms of resolution, biocompatibility and ﬂuidic sealing. The adhesive bonding is achieved by laminating a thin layer of ORDYL SY300 (<17 m) on top of the microﬂuidic part and then bonded to the other COC part. In this research, an oxygen plasma treatment for adhesion improvement was performed on COC surfaces at various plasma times. The bonding method is described in detail and the bonding quality of the chips was evaluated by a shear strength testing procedure and a leak test by pressurizing a microﬂuidic channel with an aqueous solution using an external peristaltic pump. Results are reported emphasizing the efﬁciency of the proposed approach and the developed process features high yields (>70%). © 2014 Elsevier B.V. All rights reserved. 1. Introduction The impact of microﬂuidic technologies has dramatically increased during the last few years since microﬂuidic is consid- ered as a key technology within the ﬁeld of life science [1]. Polymer based Lab-on-a-chip (LOC) devices or micro-total analysis systems (TAS) are currently hot research topics in the ﬁeld of microﬂuidics and BioMEMS [2]. The main advantages of microﬂuidic systems are that important biological operations such as pathogen detection and genotyping can be accelerated and ampliﬁed by integrating a variety of functions like sample preparation, DNA ampliﬁcation, cell capture, pumping, mixing, and detection onto a single platform with minimal or no human intervention. The advantages of poly- mers over glass and silicon as a substrate for microﬂuidic devices include [3] their biocompatibility, disposability, good chemical resistance, optical properties, low cost, and capacity for high vol- ume production using established manufacturing techniques such as hot embossing and injection molding. Several polymeric materials including polymethylmethacry- late (PMMA) [4], polycarbonate (PC) [5] polyester [6], ﬂuorinated ethylene propylene [7], and poly(ethylene terephthalate) [8] and cyclic oleﬁn copolymer (COC) [9] have been investigated for the ∗ Corresponding author. Tel.: +32 010472174. E-mail address: lamia.elﬁssi@uclouvain.be (L. El Fissi). microﬂuidics fabrication [10]. COC (Topas) which is a thermoplas- tic copolymer has been used because of its excellent properties, such as high glass transition temperatures, excellent transparency [11]. Bonding between polymer substrates is an essential fabrication step to seal and form micro-channels or micro-chambers in plas- tic LOC or TAS system since the micro-channels on the polymer layers are normally opened after the micro-machining step. Today, several bonding techniques for plastic substrates have been devel- oped such as a thermal lamination [12] the adhesive bonding [13], the thermal bonding [14,15], the laser welding [16,17], and the conventional solvent bonding [18,19]. The solvent bonding of thermoplastics takes advantage of the polymer solubility in selected solvent systems to achieve entangle- ment of polymer chains across the interface. When a thermoplastic surface is solvated, the polymer chains become mobile and can readily diffuse across the solvated layer, leading to an extensive intertwining of chains between the surfaces and resulting in excep- tionally strong bonds. The solvent bonding is carried out at room temperature or decreased temperature levels which comply with the reagent pre-storage. Furthermore, the chips are usually stored at high temperatures for several hours to accelerate the solvent evaporation after the bonding. The temperature stability of the bonds depends signiﬁcantly on the complete evaporation of the solvents, since the presence of solvents causes stress cracks and cloudiness. http://dx.doi.org/10.1016/j.sna.2014.12.016 0924-4247/© 2014 Elsevier B.V. All rights reserved.