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This paper presents a microelectromechanical systems sensor for differential scanning calorimetry (DSC) of liquid-phase biomolecular samples. The device consists of two microchambers, each of which is based on a freestanding polyimide diaphragm and surrounded by air cavities for thermal isolation. The chambers are each equipped with a thin-film gold resistive heater and temperature sensor and are also integrated with a thin-film antimony-bismuth (Sb-Bi) thermopile. For DSC measurements, the chambers are respectively filled with a biomolecular sample and a reference solution, with their temperatures varied at a constant rate. The thermopile voltage is measured to determine the differential power between the chambers for thermodynamic characterization of the biomolecules. The device is used to measure the unfolding of proteins in a small volume (1 μL) and at practically relevant concentrations (approximately 1 mg/mL). Thermodynamic properties, including the enthalpy change and melting temperature, during this conformational transition are determined and found to agree with published data.
Date of Publication: Oct. 2012