A dispensing device includes a dispenser configured to dispense a volatile material, a sensor configured to detect an environmental condition, and a nonlinear circuit element coupled to the sensor to establish a bias point. A voltage level at the bias point varies nonlinearly with respect to a current that flows through the sensor, wherein the current that flows through the sensor represents the environmental condition. The dispensing device further includes a controller coupled to the bias point. The controller controls the dispenser to dispense the volatile material in response to the environmental condition.
