AC/DC characterization and application feasibility analysis of heated microcantilever probes
The research presented in this article analyses the thermal and electrical response of a heated microcantilever atomic force microscope (AFM) probe and investigates the feasibility of utilizing said probe for various applications. A transient heat conduction equation is derived and solved using a finite element analysis (FEA) model of the cantilever system. Experimentation is also performed to confirm the veracity of the model. An increased understanding of the electrothermal behavior of the heated cantilever system and insight into possible future applications are documented in the results of this work. ^ The increasing prominence of micro/nanoscale technology in modern engineering applications has made the ability to measure thermal properties and heat transfer mechanisms with nanoscale resolution more vital. At present, this is usually accomplished using the 3ω method in conjunction with Joule heating a hot wire or a Wollaston probe. Both methods are limited, however, by the relatively large size of the heaters in the devices which is on the order of hundreds of microns in length and several microns in diameter. To address this, some studies have been conducted using silicon based heated microcantilever AFM probes with tip contact diameters on the order of tens of nanometers. This resulted in dramatically improved resolution and sensitivity. Unfortunately, the heat transfer models in these studies are typically simple 1D or 2D analytical approximations which limit their usefulness and cannot provide a complete understanding of the heat transfer within the cantilever system. This work addresses the previously stated limitations through the creation of a 3D FEA model of a monocrystalline silicon heated microcantilever using COMSOL FEA software. The model is used to fully characterize the microcantilever system. This includes analysis of heater size effect, temperature distribution, frequency and 3ω response, and environmental effects. The results of the model agree well with both theoretical expectations and experimental data. ^ In addition to characterization, an investigation into the applications of heated microcantilevers such as nanoscale thermophysical property measurement is conducted. For thermophysical property measurement, a sampling method is presented in which the microcantilever is heated beyond the melting point of a polyethylene terephthalate (PET) substrate and a sample of PET is then scooped onto the top of the heater on the cantilever. The thermal properties are examined using the 3ω method. It is found that samples smaller than 500 picograms can be detected using the methods described here. ^
"AC/DC characterization and application feasibility analysis of heated microcantilever probes"
Dissertations and Master's Theses (Campus Access).