Nanocomposite Carbon‐PDMS Material for Chip‐Based Electrochemical Detection

Abstract

This paper presents an alternative approach to create low-cost and patternable carbon electrodes suitable for microfluidic devices. The fabrication and the electrochemical performances of electrodes made of Polydimethylsiloxane doped with commercially available carbon black (C-PDMS) are described. Conductivity and electrochemical measurements performed on various carbon to PDMS ratios showed that electrodes with suitable electrochemical properties were obtained with a ratio of 25 %.Keywords: Carbon electrodes, PDMS, Microfluidics, Voltammetry, Plasma treatment DOI: 10.1002/elan.201000321 Carbon is a widely used material for electrochemistry due to inherent advantages as a low-cost, quite inert material and its wide electrochemical potential window [1]. Such electrodes are for example very well suited for most biological assays but their patterning is an issue that has to be addressed for their chip-based applications. Various approaches were developed to achieve such integration as the insertion of carbon fibres [2], screen printing carbon paste [3][4][5], micromolding carbon ink [6], pyrolysis of photoresist [7,8] and by doping photoresist with carbon particles [9]. The last solution is very versatile in obtaining various electrode geometries but suffers from the complexity of the doped photoresist preparation. Moreover, the temperature required for carbonaceous electrodes obtained from pyrolysis of photoresist layer is beyond the thermal budget of many low temperature polymer-based processes and requires specific substrates such as Si. Despite the interest of combining carbon inks with softlithography, such method still suffers from an inherent complexity for electrode integration into microfluidic devices. Indeed, the bonding of electrodes on the device material is a critical issue which is alternatively obtained by applying a small pressure between the two substrates.Here, we present a method to fabricate low-cost and patternable C-PDMS electrodes and their preliminary electrochemical performances were evaluated.Poly(dimethylsiloxane) (PDMS) is a very attractive material to fabricate microfluidic structures and is widely used in the lab-on-a-chip community. Recently, it was shown that this elastomer can be made conductive by doping it with carbon or silver nanoparticles [10,11] and carbon nanotubes [12]. Carbon doped PDMS (C-PDMS) was used to fabricate strain gauge [13] and finger print sensor [14]. Moreover, recent studies reported the integration of C-PDMS in microfluidic systems to achieve capacitive detection of droplets [15], heating in microfluidic environment [16], and also the fabrication of microfluidic components by controlling electrorheological fluids [16]. However, to our best knowledge, electrochemical characterization of doped PDMS electrodes was never reported in literature.Composite electrodes such as carbon paste electrodes are widely used in electrochemical detection as they exhibit a small capacitive current and a faradic current proportional to the total surface area of the ele...

Surface modification for PDMS‐based microfluidic devices

“…Here, the first challenge is the fabrication of flexible conductive materials suitable for use in soft lithographic techniques. An easy solution to this problem may come from the integration of a conductive material into PDMS such as metal nanoparticles, carbon black or CNTs 58, 59, 63–69.…”

“…Other examples of producing conductive PDMS‐composites for microfluidic devices involve carbon black or metal nanoparticles 68, 76, 77. Chip‐based electrochemical detection with PDMS/carbon black‐based electrodes was demonstrated by Brun et al 68. By carefully mixing the PDMS prepolymer with carbon black powder, conductive PDMS composites were produced.…”

Template‐ and Additive‐free Electrosynthesis and Characterization of Spherical Gold Nanoparticles on Hydrophobic Conducting Polydimethylsiloxane

“…The mixture was then degassed for 30 min and was kept at −15 °C prior to usage. The conductivity of the prepared C‐PDMS was determined as 10 S m −1 . A thin film of C‐PDMS was coated onto polished macroscopic gold or platinum disc working electrodes (CHI‐101, CHI 102, respectively, CH Instruments, US) having a diameter of 2 mm and cured at 80 °C overnight.…”

Dielectrophoretic capture of low abundance cell population using thick electrodes

“…The quality of the plasma bonding between C-PDMS and glass was comparable to that of PDMS and glass, thus avoiding leaks at the electrodes and ensuring a tight device as demonstrated in previous works. 22,27 We fabricated three different configurations of C-PDMS thick electrodes integrated in the walls of PDMS channels ( Fig. 1(b)).…”