Method for measuring diffusivities of compounds using microchips
First Claim
1. A method for calculating the diffusivity of a solute in a microchannel, the method comprising the steps of:
- providing a microchannel having a first end and a second end and a cross-sectional shape;
providing a first detector and a second detector that measure the concentration of solute at a first location and a second location respectively, the first and second locations being disposed between the first and second ends of the microchannel;
introducing the solute into the first end of said microchannel as a plug;
measuring a first concentration profile of the plug at the first location at a first time;
measuring a second concentration profile of the plug at the second location at a second time;
calculating a velocity based on a distance between the first location and the second location and the first and second times; and
determining the diffusivity of the solute by comparing the first concentration profile to the second concentration profile.
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Abstract
A method for determining the molecular diffusivity of a solute in a microchannel where a solute is introduced into a first end of a microchannel and a first concentration profile is measured at first and second locations along the microchannel. A theoretical concentration profile can be calculated at the second location based on the measured first concentration profile at the first location. The molecular diffusivity can be found by minimizing the error when comparing the theoretical concentration profile to the measured second concentration profile. Further, this technique allows for average velocity to be measured simultaneously with molecular diffusivity.
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Citations
10 Claims
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1. A method for calculating the diffusivity of a solute in a microchannel, the method comprising the steps of:
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providing a microchannel having a first end and a second end and a cross-sectional shape; providing a first detector and a second detector that measure the concentration of solute at a first location and a second location respectively, the first and second locations being disposed between the first and second ends of the microchannel; introducing the solute into the first end of said microchannel as a plug; measuring a first concentration profile of the plug at the first location at a first time; measuring a second concentration profile of the plug at the second location at a second time; calculating a velocity based on a distance between the first location and the second location and the first and second times; and determining the diffusivity of the solute by comparing the first concentration profile to the second concentration profile. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for measuring an average velocity of a solute in a microchannel comprising:
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providing a microchannel; introducing a solute at one end of said microchannel; measuring a first concentration profile at a first upstream location along said microchannel; determining a first time at which a feature of the first concentration profile arrives at the first upstream location; measuring a second concentration profile at a second downstream location along said microchannel; determining a second time at which the feature of the second concentration profile arrives at the second downstream location; and calculating the average velocity of said plug between said first and said second location a velocity based on a distance between the first location and the second location and the first and second times. - View Dependent Claims (10)
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Specification