A low cost highly sensitive organic thin film transistor based organic gas sensor has been investigated with pentacene as
an active and sensing layer. The variation in work function of source is lured due to gas adsorption, minimised carrier
mobility, and soaring source and also drain resistance has paved way for a change in minimum and maximum drain
current. On varying the width of active layer along with dielectric, significant variation was observed in turn on current,
and minimum and maximum drain current over a constant threshold voltage on different source to drain width
architecture. Consequently, sensitivity was formulated along with average sensitivity. The organic thin film transistor
planted devices have emerged to be superior class of sensors.