A microfluidic device for generation of monodisperse droplets and initiating a chemical reaction is provided. The microfluidic device includes a first input microchannel having a first dimension and including a first phase located therein. The device also includes a second input microchannel having a second dimension and including a second phase located therein. In accordance with the present disclosure, the second dimension is different from the first dimension and the first phase is immiscible in the second phase. A microchannel junction is also present and is in communication with the first input microchannel and the second input microchannel. The device further includes an output channel in communication with the microchannel junction and set to receive a monodisperse droplet. In the present disclosure, the difference in the first dimension and the second dimension creates an interfacial tension induced force at the microchannel junction which forms the monodisperse droplet.