A. Humidity Control
The humidity [%RH] was varied from 30 % to 80%. Each
sensor detects different humidity as shown in Fig. 3.
Resistances arisen from humidity of TGS 813, TGS 825, and
TGS 2602 sensors are displayed in Fig. 3.1, 3.2 and 3.3,
respectively.
The graphs of TGS 822 and TSG880 are not show in this
paper of which behaviors is similar to TGS 813. The
mathematical models for the resistance relative to humidity of
each sensor were employed to fit the data via the following
formulation;