3D nanogap interdigitated electrode array biosensors |
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Authors: | Kanwar Vikas Singh Allison M Whited Yaswanth Ragineni Thomas W Barrett Jeff King Raj Solanki |
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Institution: | (1) Department of Physics, Portland State University, 1719 SW 10th Ave, Rm 128, Portland, OR 97201, USA;(2) Veterans Affairs and Medicine, Oregon Health and Science University (OHSU), 3181 SW Sam Jackson Park Rd, Portland, OR 97239-3098, USA;(3) Flash Sensortech, Virogenomics Tigard, 9020 SW Washington Square Road, Suite 450, Tigard, OR 97223, USA |
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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 μg/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 μg/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. |
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