Detection of charged macromolecules by means of fi eld-effect devices (FEDs): possibilities and limitations - Electrochemical Sensors, Biosensors and Their Biomedical Applications - page 191

RE

cDNA

cDNA

V G

A
G
C
C
T
T

A
G
C
C
T
T

A
G
C
C
T
T

ssDNA

Gate insulator

V ~

Si

RE

dsDNA

C
A
A-T
G-C
C-G
C-G
T-A
T-A

C
A
A-T
G-C
C-G
C-G
T-A
T-A

C
A
A-T
G-C
C-G
C-G
T-A
T-A

V G

Gate insulator

V ~

Si

FIGURE 7.2 Schematic of a DNA sensor based on a capacitive EIS structure. For operation, a DC
(direct current) polarization voltage ( V G ) is applied via the reference electrode (RE) to set the working
point of the EIS sensor, and a small AC (alternating current) voltage ( V ) is applied to the system in order
to measure the capacitance of the sensor. ssDNA - single-stranded DNA, cDNA - complementary DNA,
dsDNA - double-stranded DNA.