An interdigitated electrode with dense carbon nanotube forests on conductive supports for electrochemical biosensors

Abstract

A highly sensitive interdigitated electrode (IDE) with vertically aligned dense carbon nanotube forests directly grown on conductive supports was demonstrated by combining UV lithography and a low temperature chemical vapor deposition process (470 °C). The cyclic voltammetry (CV) measurements of K4[Fe(CN)6] showed that the redox current of the IDE with CNT forests (CNTF-IDE) reached the steady state much more quickly compared to that of conventional gold IDE (Au-IDE). The performance of the CNTF-IDE largely depended on the geometry of the electrodes (e.g. width and gap). With the optimum three-dimensional electrode structure, the anodic current was amplified by a factor of ∼18 and ∼67 in the CV and the chronoamperometry measurements, respectively. The collection efficiency, defined as the ratio of the cathodic current to the anodic current at steady state, was improved up to 97.3%. The selective detection of dopamine (DA) under the coexistence of l-ascorbic acid with high concentration (100 μM) was achieved with a linear range of 100 nM-100 μM, a sensitivity of 14.3 mA mol-1 L, and a limit of detection (LOD, S/N = 3) of 42 nM. Compared to the conventional carbon electrodes, the CNTF-IDE showed superior anti-fouling property, which is of significant importance for practical applications, with a negligible shift of the half-wave potential (ΔE1/2 < 1.4 mV) for repeated CV measurements of DA at high concentration (100 μM).

Growth of CNT Forests on Titanium Based Layers, Detailed Study of Catalysts

“…Without water vapor not only the height of the CNTs was very low, but also the structural quality, probably because of the healing capacity of water vapor. It seems to be a reasonable explanation, nevertheless, in the literature of CCVD methods such interpretation occurs only in few cases (Sugime et al, 2018).…”

Synthesis Procedure of Highly Densely Packed Carbon Nanotube Forests on TiN

“…In recent years, much of the research in these materials has focused on the growth of dense SWNT forests on different substrates [15,16,17,18,19,20]. This architecture allows the use of these materials in different applications, including field emission, energy storage, nanoelectronics, or sensing.…”

EIS_Response_Non-planar_Interdigitated_microelectrode_Communication_Paper_JECS

“…The carbon-based nanomaterials have extraordinary electron transport, wide electrochemical window, excellent physical properties, superb biocompatibility and shares the π electron cloud with attached biomolecules to significantly increases the conductance (5)(6)(7). Micro-electrodes (µEs) have been widely applied with EIS (8)(9)(10). µEs offer the advantages of low ohmic potential drop, fast establishment of steady-state signal, and increased signal-to-noise ratio (SNR) over macro electrodes leading to increased sensitivity (8).…”

“…Hence, to enhance the sensitivity, µE is modified by extending the bio-receptor using a carbon spacer/carbon nanostructures (9,(11)(12)(13). This is achieved by complex and expensive fabrication, such as the growth of CNTs, complicated operating protocols, extensive soft-lithography (14)(15)(16)(17).…”

“…Device integration is carried out at room temperature with no equipment and minimal operator involvement/expertise.Tightly packaged carbon-based materials have been shown to form 2D and 3D porous structures(22)(23)(24)(25)(26). These carbon-based porous structures increase the contact area between the electrolyte and electrode, leading to enhanced SNR(9). It is worthwhile to note that our "open design" method allows us to pack the chip with any carbon-based transducer material.…”