Thermal Resistance of 1D Micron‐Wide Interface Under External Force Modulation

Abstract 1D µm‐wide interfaces emerge under the contact between microscale fibers and the environment. The local interfacial thermal resistance (ITR) is of great scientific and engineering importance. However, relevant studies are scarce, particularly those investigating its dependence on externally applied forces. This paper presents a systematic investigation into the ITR at the microscale interface of carbon microfibers (CMFs) in contact with a sapphire substrate. A novel experimental approach based on the Transient Electrothermal (TET) technique is developed to characterize ITR by analyzing the transient temperature response induced by step Joule heating. A critical component of this study is the systematic modulation of the applied contact force at the CMF‐sapphire contact, thereby modulating the ITR. It is observed this contact force variation (≈10 ⁻² –10 ⁻⁵ N) leads to measurable changes in ITR, with values ranging from ≈500 to 700 mK/W. The analysis incorporates considerations of effective contact area and secondary heat transfer mechanisms, such as phonon tunneling and near‐field radiative effects, and provides a holistic view of the interfacial thermal transport. The findings not only advance the fundamental understanding of heat transfer across micro/nanoscale contacts but also highlight the potential of the TET‐based method for high‐sensitivity thermal and force sensors for microelectronic applications.