3D nanogap interdigitated electrode array biosensors

Abstract

Three-dimensional interdigitated electrodes (IDEs) have been investigated as sensing elements for biosensors. Electric field and current density were simulated in the vicinity of these electrodes as a function of the electrode width, gap, and height to determine the optimum geometry. Both the height and the gap between the electrodes were found to have significant effect on the magnitude and distribution of the electric field and current density near the electrode surface, while the width of the electrodes was found to have a smaller effect on field strength and current density. IDEs were fabricated based on these simulations and their performance tested by detecting C-reactive protein (CRP), a stress-related protein and an important biomarker for inflammation, cardiovascular disease risk indicator, and postsurgical recuperation. CRP-specific antibodies were immobilized on the electrode surface and the formation of an immunocomplex (IC) with CRP was monitored. Electrochemical impedance spectroscopy (EIS) was employed as the detection technique. EIS data at various concentrations (1 pg/mL to 10 microg/mL) of CRP spiked in buffer or diluted human serum was collected and fitted into an equivalent electrical circuit model. Change in resistance was found to be the parameter most sensitive to change in CRP concentration. The sensor response was linear from 0.1 ng/mL to 1 microg/mL in both buffer and 5% human serum samples. The CRP samples were validated using a commercially available ELISA for CRP detection. Hence, the viability of IDEs and EIS for the detection of serum biomarkers was established without using labeled or probe molecules.

Evaluation of Nanomaterials-biomolecule hybrids for signal enhancement of impedimetric biosensors

“…The gold IDEA surface was functionalized using Cysteamine linker displaying free amine groups after formation of self-assemnled monolayers (SAMs). Normal rabbit IgG Abs were covalently immobilized on electrodes as in our related work [6].…”

“…Typically the binding interactions were carried out in PBS containing 0.05% tween-20 as a detergent (PBST) and the electrochemical measurements were made in 10mM PBS containing redox 6 ]. The oscillation voltage was kept at 25mV with a DC bias voltage of 220mV.…”

“…Nanogap interdigitated electrodes were used with EIS as a detection technique as described in our previous work [6]. Abs were immobilized on the transducer electrodes.…”

Electrochemical nanosensors: advances and applications

“…57 Nanoelectrochemical immunosensors usually involve the immobilization of an antibody on either discrete nanowires or on larger electrodes modified with nanomaterials. Singh et al 58 developed gold interdigitated electrodes (IDEs) with submicron separation for the detection of CRP. Finite element analysis was performed to give an indication of the optimal interelectrode spacing and electrode height.…”

Towards Understanding Surface Wetness and Corrosion Response of Mild Steel in Marine Atmospheres

“…Particles smaller than the gap could also be examined provided they are configured in such a way as to provide continuous conductive bridges across the electrodes, as could be achieved by a relatively high particle loading density. In recent years interdigitated electrode sensor geometries have been successfully scaled down for molecular and vapor phase chemical sensing with electrode spacing on the order of 100 nm [72][73][74], and sensors with gaps down to 1 µm are commercially available. Utilizing sensors with smaller spacing could extend the applicability of this method for study of finer size particles.…”