A Large-Scale, Wireless Electrochemical Bipolar Electrode Microarray

Chow, Kwok Fan; Mavré, François; Crooks, John A.; Chang, Byoung Yong; Crooks, Richard M.

doi:10.1021/ja902683f

Cited by 218 publications

(211 citation statements)

References 11 publications

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“…In summary, the method reported here is suitable for rapid screening of large-scale arrays of electrocatalysts. 3 Importantly, there is a direct relationship between the activity of the electrocatalyst as determined by voltammetry (Figure 2b) and the number of dissolved Ag microbands. This suggests that this method has the potential to provide quantitative kinetic information about electrocatalytic reactions.…”

Section: * S Supporting Informationmentioning

confidence: 96%

“…This means that large arrays of electrodes can be controlled simultaneously using a single voltage source. 3 Finally, the current flowing through a BPE can be monitored visually by electrogenerated chemiluminescence 4 or, as implemented here, by following the electrodissolution of a Ag film. 2 Methods for screening large arrays of electrocatalysts have emerged over the past ∼15 years.…”

Section: * S Supporting Informationmentioning

confidence: 99%

“…This is because it is not necessary to make a direct electrical connection to each electrode, which is an intrinsic property of BPEs and the principal reason for using them in an array format. 3 The basic operating principles of BPEs, along with many interesting applications, have been previously described in the scientific literature. 1−14 A driving voltage E tot applied across a microchannel containing a conductive electrolyte solution (Scheme 1b) is dropped nearly linearly over the length of the microchannel.…”

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Bipolar Electrodes for Rapid Screening of Electrocatalysts

2011

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We report a method for rapid screening of arrays of electrocatalyst candidates. The approach is based on simultaneous activation of the oxygen reduction reaction (ORR) and Ag electrodissolution at the cathodic and anodic poles, respectively, of bipolar electrodes (BPEs). Because the electrochemical activity of the two poles is directly coupled via the BPE, the extent of Ag electrodissolution is directly related to the ORR activity. The screening process lasts ∼12 min. Because Ag dissolution provides a permanent record of catalyst activity, the screening results can be determined by simple optical microscopy after the electrochemical experiment. The method has the potential to provide quantitative information about electrocatalyst activity.H ere we report a new and potentially powerful method for rapid screening of electrocatalysts. The principle is illustrated in Scheme 1, with specific reference to evaluation of the activity of electrocatalysts for the oxygen reduction reaction (ORR). The top frame of Scheme 1a shows an array of three bipolar electrodes (BPEs). 1 The ORR electrocatalyst candidates are deposited onto the cathodic poles of the BPEs, while the anodic poles are composed of parallel Ag microband electrodes. The Ag microbands of each electrode are in electrical contact with one another and with the ORR catalyst via an underlying indium-doped tin oxide (ITO) contact. When a sufficiently high potential (E tot , Scheme 1b) is applied to the solution in the fluidic channel via a pair of driving electrodes, the ORR proceeds at the cathodic poles and the Ag microbands undergo electrodissolution. 2 The efficiency of the ORR catalyst is then determined by counting the number of dissolved Ag microband electrodes: the more bands that dissolve, the better the catalyst. In fact, as we will show, there is a direct thermodynamic link between the overpotential required for the ORR (Scheme 1c) and the number of Ag microbands remaining after the experiment (Scheme 1a). Although we demonstrate this screening method using just three BPEs, arrays of arbitrary size can be monitored in this way with very little additional technological overhead. This is because it is not necessary to make a direct electrical connection to each electrode, which is an intrinsic property of BPEs and the principal reason for using them in an array format. 3 The basic operating principles of BPEs, along with many interesting applications, have been previously described in the scientific literature. 1−14 A driving voltage E tot applied across a microchannel containing a conductive electrolyte solution (Scheme 1b) is dropped nearly linearly over the length of the microchannel. 6 If a conductive wire of sufficient length is present in the microchannel, it will function as a BPE. 1 Specifically, when the interfacial potential differences between the poles of the BPE and the electrolyte solution (ΔE elec , Scheme 1a) are sufficiently high, faradaic processes occur simultaneously: a reduction at the cathodic pole and an oxidation at the a...

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Section: * S Supporting Informationmentioning

confidence: 96%

Section: * S Supporting Informationmentioning

confidence: 99%

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Bipolar Electrodes for Rapid Screening of Electrocatalysts

2011

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“…BPEs provide a means to vastly simplify the design of microelectrochemical arrays. 24,25 For example, Figure 1a shows the basic design of a small, wireless DNA microelectrochemical array. It consists of three Au BPEs (1.00 × 0.25 mm) housed at the center of a PDMS microchannel (1.20 cm long, 1.75 mm wide, and 28 µm high) filled with an aqueous solution of Ru(bpy) 3 2+ and TPrA ( Figure 1b).…”

Section: +mentioning

confidence: 99%

Bipolar Electrodes: A Useful Tool for Concentration, Separation, and Detection of Analytes in Microelectrochemical Systems

et al. 2010

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Over the past decade, bipolar electrochemistry has emerged from relative obscurity to provide a promising new means for integrating electrochemistry into lab-ona-chip systems. This article describes the fundamental operating principles of bipolar electrodes, as well as several interesting applications.A bipolar electrode (BPE) is an electronic conductor in contact with an ionically conductive phase. When a sufficiently high electric field is applied across the ionic phase, faradaic reactions occur at the ends of the BPE even though there is no direct electrical connection between it and an external power supply. In this article, we describe the fundamental principles and some electroanalytical applications of BPEs for array-based sensing, separations, and concentration enrichment in microelectrochemical systems. Specifically, we show how the latter three operations, which are normally thought of as arising from different phenomena, are linked by processes occurring on and near BPEs confined within a convenient, miniaturized microfluidic format. The results presented here demonstrate that under a particular set of conditions, up to 1000 well-defined BPEs can be simultaneously activated and interrogated using just a single pair of driving electrodes. Furthermore, a slight change to the resistance of the buffer solution within the microfluidic channel leads to the separation and concentration enrichment of charged analytes. OVERVIEW OF BIPOLAR ELECTROCHEMISTRYA traditional three-electrode electrochemical cell, which consists of a working electrode, an auxiliary electrode, and a reference electrode, is illustrated in Scheme 1a. In this configuration, the potential of the working electrode, which is related to the energy of the electrons in the electrode, is controlled (versus a reference electrode) using a potentiostat. The potential of the solution is not directly controlled; in other words, it is at a floating potential that (in the absence of an externally applied electric field) depends on the composition of the solution. When the potential of the working electrode is set to a value more negative than that of an electroactive molecule in the solution, electrons may (depending upon kinetics) transfer from the electrode to reduce species in solution (Scheme 1b; note that positive potentials are up in this diagram to make it consistent with Scheme 1c). Similarly, oxidation reactions occur when the electron transfer is in the opposite direction. The faradaic current measured in the circuit connecting the working and auxiliary electrodes is a direct FRANÇ OIS MAVRÉ

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“…19,31 To test the feasibility of using ECL-based readout for an array of paper-supported BPEs, a µPAD composed of 18 individual BPEs was fabricated. The BPE array µPAD was filled with 40.0 µL of 0.10 M phosphate buffer solution (pH 6.9) containing 5.0 mM Ru(bpy) 3 2+ and 25.0 mM DBAE.…”

Section: Ecl Detection On a Bpe Array µPadmentioning

confidence: 99%

Paper-Based Bipolar Electrochemistry

Renault¹,

Scida²,

Knust³

et al. 2013

Journal of Electrochemical Science and Technology

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:We demonstrate that carbon electrodes screen-printed directly on cellulose paper can be employed to perform bipolar electrochemistry. In addition, an array of 18 screen-printed bipolar electrodes (BPEs) can be simultaneously controlled using a single pair of driving electrodes. The electrochemical state of the BPEs is read-out using electrogenerated chemiluminescence. These results are important because they demonstrate the feasibility of coupling bipolar electrochemistry to microfluidic paperbased analytical devices (µPADs) to perform highly multiplexed, low-cost measurements.

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A Large-Scale, Wireless Electrochemical Bipolar Electrode Microarray

Cited by 218 publications

References 11 publications

Bipolar Electrodes for Rapid Screening of Electrocatalysts

Bipolar Electrodes for Rapid Screening of Electrocatalysts

Bipolar Electrodes: A Useful Tool for Concentration, Separation, and Detection of Analytes in Microelectrochemical Systems

Paper-Based Bipolar Electrochemistry

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