A microfluidic device is provided for regulating the temperature of a sample fluid flowing therethrough, as well as, a method of regulating the temperature of the sample fluid flowing through the microfluidic device. The microfluidic device includes a body member defining a fluid channel for allowing the sample fluid to flow therethrough and a first regulating channel. A regulating fluid having a predetermined temperature flows through the regulating channel adjacent the fluid channel so as to effectuate a heat exchange with the sample fluid flowing through the fluid channel to regulate the temperature thereof.