Femtogram-Level Thermophysical Property Measurement of Polymeric Samples Using Heated Microcantilevers

This article investigates thermophysical property measurement of femtogram-level polymeric samples by using the 3ω method on a heated microcantilever probe. A localized thermal scooping method was employed to acquire 449 fg of polyethylene terephthalate (PET) sample, measured gravimetrically, directly onto the heater of the cantilever. It is shown that the sample case has a 3ω signal that is smaller in magnitude than the bare case, suggesting that sample properties could be determined using the processes discussed here. A finite element analysis (FEA) model was also developed to compute the steady periodic behavior of the cantilever in the frequency domain. In order to drastically reduce the computational cost and consider the transient effect of the surrounding air, the FEA model implements the complex thermal conductance of the air as the boundary condition rather than modeling the air as a separate domain. The comparison of the modified model with the model that includes the air in the system reveals that the running time has improved by one order of magnitude while showing excellent agreement. The obtained results will expand the characterization and functionality of microcantilevers leading to advancements in localized thermal analysis.