Carbon Nanotube Fiber Microelectrodes Show a Higher Resistance to Dopamine Fouling

Abstract

We have compared the properties and resistance to DA fouling of a carbon nanotube fiber (CNTF) microelectrode to a traditional carbon fiber (CF) microelectrode. These two materials show comparable electrochemical activities for outer-sphere and inner-sphere redox reactions. Although the CNTF might have a higher intrinsic RC constant, thus limiting its high-frequency behavior, the CNTF show a significantly higher durability than the CF in terms of electrode stability. During constant oxidation of 100 μM DA, the signal measured by the CNTF microelectrode shows a 2-hour window over which no decrease in current is observed. Under the same conditions, the current obtained at the CF microelectrode decreases by almost 50 %. A model of the fouling process, assuming the formation of growing patches of insulator on the surface, has been compared to the data. This model is found to be in good agreement with our results, and indicates a growth rate of the patches in the 0.1 - 2 nm s−1 range.

Delayed voltammetric with respect to amperometric electrochemical detection of concentration changes in microchannels

“…The magnitude of i p is known to be proportional to the square root of SR, as it is directly related to the diffusion layer thickness. [26][27][28] The graph presented in Figure 2B shows a clear linear relationship between i p and SR 1/2 . Similarly, Figure 2C shows typical CV traces obtained for increasing ν (0, 2, 10, 20 and 30 µl s -1 ).…”

Cathodic pretreatment improves the resistance of boron-doped diamond electrodes to dopamine fouling

“…The traces were largely comparable for the two pretreatments ( Figure 1D), as indicated by the similar charge Qf transferred through the electrode during the fouling procedure (~ 6.5±1.1 mC), even though the cathodic preparation induces a slightly higher current. A slight shoulder (indicated by the arrow on Figure 1D) can also be observed for the cathodically-treated surface, an indication of the growth of the DA insulating sites on the electrode [13]. Fouling generally induces a decrease in the measured current.…”

Interplay between the potential waveform and diffusion layer dynamics determines the time-response of voltammetric detection in microchannels

“…Indeed, several reports have highlighted the specific behaviour of electrochemistry in microchannels [9][10][11][12][13], where the mass transport characteristics are radically different from the ones encountered in traditional conditions of electrochemistry [14][15][16]. The fast time response and sensitivity of electrochemical sensors is one of their most attractive features, allowing for example the detection of neuronal transmission [17][18][19][20][21][22] or single molecules [23,24]. The effects of convection and diffusion on the temporal behaviour of electrochemical sensors therefore have to be studied carefully for these devices.…”