Page 48 - Organic Electronics in Sensors and Biotechnology

Scaling Effects in Organic Transistors and Transistor-Based Chemical Sensors 25

8

6
Count of devices 4

2

0
0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07
2
Mobility [cm /(V·s)]
FIGURE 1.15 Statistics on the mobility of the measured devices (L = 8–35 nm).
(Reprinted with permission from Ref. 40. Copyright 2004, American Institute of
Physics.)

1.2 Scaling Behavior of Chemical Sensing with Organic
Transistors

1.2.1 General Introduction to Organic Transistors
for Sensing Applications
In recent years chemical sensing has become increasingly important
not only from an industrial standpoint but also from a homeland
security perspective. Sensors with the ability to detect chemicals,
such as volatile organic compounds (VOCs), and biological species,
including DNA and proteins, have been given more and more atten-
tion by the scientific and industrial communities. This is due to their
great potential in an array of applications comprising manufacturing,
transportation, environmental monitoring, process control, health
care, homeland security, and national defense. 84–88 However, most of
the commercial products available at present are bulky and costly
and require long times for sampling and analyzing data. A novel
scheme that employs portable and inexpensive devices with the
advantage of fast data retrieval is desired. Miniaturization is
demanded for all types of sensors because of the needs of better por-
tability, higher sensitivity, lower power dissipation, and better device
integration. 89, 90 There have been many types of sensors evaluated for
this purpose, utilizing various techniques of transduction such as