Calorimetric biosensors with integrated microfluidic channels.

Area of Science:

• Biomedical Engineering
• Chemical Engineering
• Physical Chemistry

Background:

• Accurate measurement of thermodynamic properties in biochemical reactions is crucial for understanding biological processes.
• Existing methods for thermal analysis of biological fluids and reactions can be limited in real-time capability and sensitivity.

Purpose of the Study:

• To design, fabricate, and test a novel microfluidic device for real-time calorimetric measurements of biochemical reactions.
• To evaluate the device's performance in measuring enthalpy changes and thermal properties of biological fluids.
• To demonstrate the potential for fundamental thermodynamic studies and multi-analyte detection using microthermopile-based thermal biosensors.

Main Methods:

• Fabrication of a freestanding microthermopile using p-type polysilicon/gold on a thermally isolated membrane.
• Integration of the microthermopile with a glass microfluidic reaction chamber.
• Performance testing using enzymatic reactions (glucose oxidase, catalase, urease) in both batch and continuous flow modes.

Main Results:

• The microthermopile exhibited a sensitivity of 0.94 V/W and a thermal time constant < 100 ms.
• Achieved sensitivities of 53.5 microV/M for glucose, 26.5 microV/M for hydrogen peroxide, and 17 microV/M for urea.
• Demonstrated a detection limit of approximately 2 mM for glucose in continuous flow.

Conclusions:

• The developed microfluidic calorimetric device enables real-time enthalpy change measurements for biochemical reactions.
• The device shows promise for fundamental thermodynamic studies and can be extended for multi-analyte detection with immobilized enzymes.
• This microthermopile-based thermal biosensor offers a sensitive platform for analyzing biological fluids and reactions.