As electronic design allows higher throughput in small packages, dissipating the heat load becomes a critical design factor. Available cooling approaches, such as extruded heat sinks, are insufficient to meet these ever-increasing cooling needs. The industry has found an ideal solution in heat pipes. Due to the emergence of high power equipment, development of more effective thermal control devices is warranted. During the past decades, many microscale heat pipes were invented, developed, and are still being researched. The micro Loop Heat Pipe (ìLHP) under development is a next generation micro heat transfer device that utilizes the latent heat of a working fluid and has excellent heat transport capability as compared with that of standard metallic cooling devices. A family of planar LHPs based upon the use of a radically different type of wick structure made of planar coherent porous silicon (CPS) was researched, modified, and developed for several years at the University of Cincinnati. In this work, histories, configurations, principles, and mathematical modeling of the microscale heat pipes are surveyed. The description of the visualization LHP and the fourth generation LHP, their operation principles, operating ranges, and energy transport capability are discussed. The former one was constructed to improve our understanding of the complex phenomena in the loop and demonstrate operation, by observing through the transparent materials. The latter one was a series of planar LHP consisted of evaporator, condenser, and stainless steel tube and tested under vacuum conditions. Both systems showed the excellent heat dissipation capability.