Thermal Analysis of Nanogram Quantities Using a Micromechanical Cantilever Sensor

摘要

Thermal analytical techniques, such as thermogravimetry, are routinely used for forensic and material analysis, and typically require sample masses of a few milligrams. Tracking the resonance frequency of a micromechanical cantilever sensor as a function of temperature permits tiny changes of the actuated sensor mass to be determined. Such changes can arise from an additional sample which is placed on the cantilever sensor. A piezoresistive cantilevers can be operated as microbalance by determining its resonance vibration amplitude. The electrical current through the piezoresistive layer produces an electrical power dissipation, which directly heats the micromechanical device. The presented micromechanical thermogravimetry technique has a mass resolution which is in the picogram range. This is demonstrated in quantitative analysis of a dehydration, a desorption, and a decomposition reaction of nanogram materials.