High sensitivity, transparent, flexible strain sensors based on ultrathin graphene films are demonstrated by C.-T. Lin, Y. Fang, H. Zhu, and co-workers on page 1322. The cost-effective, ultrathin graphene films are fabricated at the liquid/air interface due to the Marangoni effect. This novel approach makes graphene a promising material for electronic skin, wearable sensors, and health monitoring platforms.