title: A simple method for patterning poly(dimethylsiloxane) barriers in paper using contact-printing with low-cost rubber stamps.
abstract: This paper presents a simple and low-cost method for patterning poly(dimethylsiloxane) (PDMS) barriers in porous support such as paper for the construction of flexible microfluidic paper-based analytical devices (μPADs). The fabrication method consisted of contact-printing a solution of PDMS and hexane (10:1.5 w/w) onto chromatographic paper using custom-designed rubber stamps containing the patterns of μPADs. After penetrating the paper (∼30 s), the PDMS is cured to form hydrophobic barriers. Under optimized conditions, hydrophobic barriers and hydrophilic channels with dimensions down to 949±88 μm and 771±90 μm (n=5), respectively, were obtained. This resolution is well-suitable for most applications in analytical chemistry. Chemical compatibility studies revealed that the PDMS barriers were able to contain some organic solvents, including acetonitrile and methanol, and aqueous solutions of some surfactants. This find is particularly interesting given that acetonitrile and methanol are the most used solvents in chromatographic separations, non-aqueous capillary electrophoresis and electroanalysis, as well as aqueous solutions of surfactants are suitable mediums for cell lyses assays. The utility of the technique was evaluated in the fabrication of paper-based electrochemical devices (PEDs) with pencil-drawn electrodes for experiments in static cyclic voltammetry and flow injection analysis (FIA) with amperometric detection, in both aqueous and organic mediums.
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Av. Pres. Antônio Carlos, 6627 Pampulha, 31270-901 Belo Horizonte, MG, Brazil.
authors.forename: Karina Lopes
authors.initials: KL
authors.lastname: Dornelas
authors.affiliation: Department of Food Science, University of Udine, Udine, Italy.
authors.forename: Nicolò
authors.initials: N
authors.lastname: Dossi
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Av. Pres. Antônio Carlos, 6627 Pampulha, 31270-901 Belo Horizonte, MG, Brazil. Electronic address: evandrop@ufmg.br.
authors.forename: Evandro
authors.initials: E
authors.lastname: Piccin
mesh_terms: D000082:Acetaminophen / Q000032:analysis; D002854:Chromatography, Paper / Q000295:instrumentation / Q000379:methods; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D004566:Electrodes; D004867:Equipment Design; D017022:Flow Injection Analysis; D006586:Hexanes / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods; D010209:Paper; D011327:Printing; D012408:Rubber; D012997:Solvents / Q000737:chemistry
chemical_list: D004129:Dimethylpolysiloxanes; D006586:Hexanes; D012997:Solvents; D000082:Acetaminophen; C013830:baysilon; D012408:Rubber
keywords: Contact-printing; Electrochemical detection; Microfluidic devices; Paper-based analytical devices; Paper-based electrochemical devices; Pencil-drawn electrodes