Airflow sensor, system and method for detecting airflow within an air handling system

An airflow sensor including a housing, a flexible substrate, and electrical components. The housing defines an internal compartment and a top face opening. The substrate includes circuitry traces, and defines a front and a back. The substrate is disposed within the compartment such that the back is exposed relative to the opening. The electrical components are electrically connected to the circuitry traces, extending from the front of the substrate opposite the opening, and include a heated temperature sensor spaced from a baseline temperature sensor. During use, airflow interfaces with the substrate back to cool the heated temperature sensor. The extent of this cooling as compared to the baseline temperature sensor is indicative of airflow. The system and method include detecting the presence or absence of airflow based upon a temperature differential between the temperature sensors as well as a rate of change in the temperature differential.