Thermal Properties Measurements Of Micro-Nano Materials Using The 3-Omega Technique

The micro-nano materials is widely used in every domain. The measurement of thermal transport properties of micro-nano materials is a big challenge due to the limited size of sample. Therefore, the measurement method of bulk materials could not apply. Under this condition, the 3-Omega method measurement system was developed which was applied to micro-nano materials. Many micro-nano materials widely used could be measured though this method.Firstly, the relationship between the thermal conductivity of the sample and the voltage signal was analyzed based on the theory of the 3-Omega method. And we built the 3-Omega experimental platform that could be used to measure the thermal conductivity of solid and liquid materials.Then, some standard materials, such as silicon, etc., were measured to test and adjust the experimental system. We measured the thermal conductivity of silicon is about 113W/m-K. It is slightly lower than 135W/m-K in the literature. The reason is that our silicon sample is with impurity, not pure. Additionally, we measured the thermal conductivity of Pyrex7740. The sample was usually used to verify the accuracy of the experiment system of thermal measurement. The measured thermal conductivity is about 1.31W/m-K. It is almost the same as the value of literature. So it effectively proves that the built 3-Omega measurement system is accuracy.Next, we designed the new probe to measure the thermal properties of liquid materials. Firstly, in order to test the experimental platform, we performed the measurement of the thermal conductivity of the standard liquid materials, e.g. ethylene glycol. Compared with the standard value in literature, our measured value is less than 1%, which is in a reasonable error range. It can also effectively prove that our experimental system could measure accurately the thermal properties of fluid samples. Secondly, we measured the thermal conductivity of nano-lubricants which is widely used in the mechanical field. Results exhibit an increase in the thermal conductivity by approximately 12-16%, due to the addition of nano particles. It is of great significance to improve the thermal dissipation of mechanical components. Besides, we measured the thermal conductivity of graphite nanofluids which was used to increase efficiency in the solar desalination. Compared with pure water, its thermal conductivity increases by 13%, which would improve the product in the process of solar desalination.At last, we studied the thermal conductivity of hydrogel widely used in the medical and industrial fields. Its thermal properties have important impacts on its application in these fields. However, the thermophysical properties have not been given much attention. Our study indicates that the thermal conductivity of hydrogel is related to its cross-link degree. The thermal conductivity increases with the increasing cross-link degree. In addition, the dependence of thermal conductivity on temperature was also investigated. It is found that the thermal conductivity increases as the temperature increases.