Ultrasound contrast agents, comprised of phospholipid-coated microbubbles, can be produced as monodisperse populations using a microfluidic flow-focusing device. However, microbubble coalescence remains a significant challenge. High production temperatures (e.g., 55 °C) can be used to suppress coalescence, but it complicates the microfluidic device design and is incompatible with targeting agents and drug conjugates. This study investigates the production of monodisperse microbubbles at room temperature with the addition of the amphiphilic surfactant Pluronic F68. Two 1,2-distearoyl-