A polymer-based MEMS differential scanning calorimeter

Abstract We present a flexible, polymer-based MEMS differential scanning calorimetric (DSC) device integrating highly sensitive thermoelectric sensing, real-time temperature monitoring and microfluidic sample and reagent handling for the thermodynamic characterization of biomolecules with minimized sample consumption. The device, based on an inexpensive, commercially available polymer substrate, consists of a pair of calorimetric microchannels that are integrated with resistive temperature sensors and heaters as well as an antimony–bismuth (Sb–Bi) thermopile. For DSC measurements, the two channels are filled respectively with a biomolecular sample and a reference solution, whose temperatures, measured in situ using the resistive temperature sensors, are varied at a constant rate using closed-loop temperature control. The difference in the thermal power between the sample and reference induces a temperature difference, which is measured using the thermopile for thermodynamic characterization of the biomolecules. We demonstrate the utility of this MEMS DSC device by measuring the unfolding of lysozyme in a small volume (1 μL), and at practically useful protein concentrations (5 mg/mL). Thermodynamic properties of lysozyme, such as the molar enthalpy change and melting temperature at different lysozyme concentrations, have been obtained and found to agree with published data.