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Nanogap Capacitors for Label Free DNA Analysis

Published online by Cambridge University Press:  01 February 2011

Joon Sung Lee
Affiliation:
Berkeley Sensor and Actuator Center Department of Bioengineering, University of California at Berkeley, Berkeley, CA 94720
Yang-Kyu Choi
Affiliation:
Berkeley Sensor and Actuator Center Department of Bioengineering, University of California at Berkeley, Berkeley, CA 94720
Michael Pio
Affiliation:
Berkeley Sensor and Actuator Center Department of Bioengineering, University of California at Berkeley, Berkeley, CA 94720
Jeonggi Seo
Affiliation:
Berkeley Sensor and Actuator Center Department of Bioengineering, University of California at Berkeley, Berkeley, CA 94720
Luke P. Lee
Affiliation:
Berkeley Sensor and Actuator Center Department of Bioengineering, University of California at Berkeley, Berkeley, CA 94720
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Abstract

Nanogap capacitors are fabricated for DNA hybridization detection. Without labeling, the nanogap capacitors on a chip can function as DNA microarray sensors. The difference in dielectric properties between single-stranded DNA and double-stranded DNA permits use of capacitance measurements to detect hybridization. To obtain high detection sensitivity, a 50 nm gap capacitor was fabricated using a Si-nanotechnology. To ensure proper measurement of DNA's dielectrical properties, the probe ssDNA was first immobilized onto the electrode surface using self-assembly monolayers and allowed to hybridize with the target ssDNA. The capacitance changes were measured for 35-mer homonucleotides. The self-assembly monolayer and DNA immobilization events were verified independently by contact angle measurement and FTIR. Capacitance values are measured at frequencies ranging from 75 kHz to 5 MHz, using 0 VDC bias and 25 mVAC signals. Approximately 9% change in capacitance was observed after DNA hybridization at 75 kHz.

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

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