Electrochemical characterization of parylene-embedded carbon nanotube nanoelectrode arrays

Abstract

A novel parylene-embedded carbon nanotube nanoelectrode array is presented for use as an electrochemical detector working electrode material. The fabrication process is compatible with standard microfluidic and other MEMS processing without requiring chemical mechanical polishing. Electrochemical studies of the nanoelectrodes showed that they perform comparably to platinum. Electrochemical pretreatment for short periods of time was found to further improve performance as measured by cathodic and anodic peak separation of K 3 Fe(CN) 6 . A lower detection limit below 0.1 µM was measured and with further fabrication improvements detection limits between 100 pM and 10 nM are possible. This makes the nanoelectrode arrays particularly suitable for trace electrochemical analysis.

Comparison of two different carbon nanotube-based surfaces with respect to potassium ferricyanide electrochemistry

“…Anodic I pa and cathodic I pc peak currents were taken from the linear fit of the voltammogram where no electrochemical analyte activity was observed [16,17]. The electroactive area (A) was obtained from the slope of the cathodic peak (I pc ) versus the square root of the scan rate ( ffiffi ffi v p ) at a K 4 Fe(CN) 6 concentration of 5 mM referring to the previous mentioned expression (Eq.…”

“…In addition, considering once again the Randles-Sevcik equation, the sensitivity (S) and detection limit were computed since these are two important parameters in sensing applications. The sensitivity per electrode area was evaluated from the angular coefficient of the straight line obtained by plotting current density values versus the K 4 Fe(CN) 6 concentration [4,17]. To evaluate this parameter, we varied the target concentration from 0 to 25 mM by steps of 5 mM at a scan rate of 100 mV/s.…”

Comparing sensitivities of differently oriented multi-walled carbon nanotubes integrated on silicon wafer for electrochemical biosensors

“…The cathodic peak currents (I pc ) were taken from the baseline of the voltammogram [17,18]. The baseline current was determined by a linear fit of the voltammogram where no electrochemical analyte activity was observed.…”

“…The baseline current was determined by a linear fit of the voltammogram where no electrochemical analyte activity was observed. For a reversible reaction at standard temperature the expected peak current, I p , can be computed referring to the Randles-Sevcik equation [17,18] …”

Strain-Based Electrical Properties of Systems of Carbon Nanotubes Embedded in Parylene

“…Parylene-C (p-xylene) was chosen as the material for the flexible substrate because of its excellent chemical resistance and its ability to coat samples with high levels of uniformity and penetration. Other groups mention coating nanotubes with parylene-c for the purpose of nanotube protection, but have not attempted a transfer onto a parylene substrate [13][14]. We placed the device to be coated inside a PDS 2010 Parylene coater and deposited 19 grams of parylene throughout the chamber, resulting in an actual coating thickness of 25 µ m. Using standard microfabrication techniques, release of the SWCNT-parylene system was accomplished by wet etching the silicon substrate.…”