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Theoretical modeling and experimental evaluation of a microscale molecular mass sensor
Colin D Costin1, Adam D McBrady, Milton E McDonnell
1Center for Process Analytical Chemistry (CPAC), Department of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700, USA.
Analytical Chemistry
|May 18, 2004
Summary
A new theoretical model for a microscale molecular mass sensor (micro-MMS) enables precise molecular mass determination by measuring diffusion coefficients. This sensor technology offers a tunable mass range for various analytes.
Area of Science:
- Analytical Chemistry
- Physical Chemistry
- Nanotechnology
Background:
- Microscale molecular mass sensors (micro-MMS) offer novel analytical capabilities.
- Measuring refractive index gradients (RIG) in microchannels is a key technique.
Purpose of the Study:
- To present a theoretical model for a micro-MMS.
- To establish a method for determining analyte molecular mass and diffusion coefficients.
- To explore the sensor's tunable mass range and calibration capabilities.
Main Methods:
- Developed a theoretical model for micro-MMS operation.
- Utilized laminar flow and diffusion in a microchannel.
- Measured diffusion-induced RIG via laser beam deflection.
- Analyzed signal ratios at different detection positions.
- Experimentally validated model parameters (beam radii, flow rates).
Main Results:
- The model accurately predicts micro-MMS output.
- Key parameters influencing RIG measurement identified: beam radius, time intervals, merge point.
- Demonstrated tunable molecular mass range from <10^2 to >10^8 g/mol.
- Achieved a universal calibration for determining unknown diffusion coefficients.
Conclusions:
- The theoretical model provides a robust framework for micro-MMS operation.
- Micro-MMS technology is versatile for molecular mass and diffusion coefficient analysis.
- The sensor's design allows for tuning the detectable molecular mass range.