Abstract: A sorting system including a flow cell with a first inlet, a second inlet, and an outlet. The sorting system also includes a buffer supply in fluid communication with the first inlet, a sample source in fluid communication with the second inlet, a light source configured to generate a light beam that intersects the flow cell, and a sensor aligned with the light source and configured to detect a characteristic of the light beam. An air valve is configured to generate an airflow at the outlet of the flow cell, and control of the air valve is based on the characteristic of the light beam detected by the sensor.