Abstract: A microdroplet or microparticle with Janus or core-shell internal morphology, which is obtained under the control of phase separation of high-concentration NIPAAm formed at 25° C. or more in a microfluidic device, is provided. The microdroplet or microparticle shows an anisotropic volume change according to a change in temperature, and can also serve as a fat-soluble/water-soluble carrier, and thus can be used as a new material for medical supplies in the field of various applications in the future.