This paper presents a novel miniature airflow energy harvester for wireless sensing applications. The energy harvester consists of a wing that is attached to a cantilever spring. The wing oscillates in response to a steady airflow. An electromagnetic transducer is used to extract electrical energy from the airflow-induced oscillations. Both vertical and horizontal orientations are studied. Experiments show that such a generator can operate at airflow speeds as low as 1.5 m·s-1, which compares well to turbines. When the airflow speed is over 2 m·s-1, the average output power exceeds 90 μW, which is sufficient for powering wireless sensor nodes in heat, ventilation, and air conditioning systems in buildings.