Method and Apparatus for Comparing Optical Properties of Two Liquids

Patent metadata

Field	Value
Publication number	US-2020240913-A1
Application number	US-202016850212-A
Country	US
Kind code	A1
Filing date	Apr 16, 2020
Priority date	Oct 18, 2017
Publication date	Jul 30, 2020
Grant date	—

Abstract

For comparing first optical properties of a first fluid with second optical properties of a second fluid a first transparent grating having a grating constant is made of the first liquid, and a second transparent grating also having the grating constant is made of the second liquid. The second transparent grating is arranged at a lateral offset of less than 45% of the grating constant with regard to the first transparent grating such that grating bars of the first and second transparent gratings are arranged side by side. Coherent light is directed onto the first and second transparent gratings such that light which passed through the grating bars of the first and second transparent gratings forms a diffraction pattern comprising intensity maxima. Two light intensities of two intensity maxima of a same order higher than zero are measured and compared to each other.

First claim

We claim:

1 . A method of comparing first optical properties of a first fluid with second optical properties of a second fluid,
wherein a first transparent grating having a grating constant is made of the first liquid, wherein a second transparent grating also having the grating constant is made of the second liquid, wherein the second transparent grating is arranged at a lateral offset of less than 45% of the grating constant with regard to the first transparent grating such that grating bars of the first and second transparent gratings are arranged side by side, wherein coherent light is directed onto the first and second transparent gratings such that light which passed through the grating bars of the first and second transparent gratings forms a diffraction pattern comprising intensity maxima, wherein two light intensities of two intensity maxima of a same order higher than zero are measured and compared to each other.

2 . The method of claim 1 , wherein the two light intensities of two intensity maxima of the first or second order are measured and compared to each other.

3 . The method of claim 1 , wherein a refractive index difference between a first refractive index of the first fluid and a second refractive index of the second fluid is calculated from the two light intensities of the two intensity maxima of the same order.

4 . The method of claim 3 , wherein the refractive index difference is calculated from a difference of the two light intensities of the two intensity maxima of the same order divided by a sum of the two light intensities of two intensity maxima of the same order and by a constant.

5 . The method of claim 1 , wherein at least one of the first and the second fluids contain biological cells.

6 . The method of claim 5 , wherein a temporal development of the two fluids is monitored by repeatedly directing the coherent light onto the first and second transparent gratings and measuring the two light intensities of the two intensity maxima of the same order.

7 . The method of claim 1 , wherein the first and the second transparent gratings are made by filling first and second sets of parallel fluidic channels in a microfluidic chip with the first and second fluid, respectively.

8 . The method of claim 7 , wherein the microfluidic chip is reflective for the coherent light.

9 . The method of claim 7 , wherein the microfluidic chip is transparent for the coherent light.

10 . The method of claim 1 , wherein the coherent light is directed through a slit or a hole in a tilted mirror onto the channel plate, wherein the mirror deflects the diffraction pattern towards a camera of the light detector.

11 . An apparatus for comparing first optical properties of a first fluid with second optical properties of a second fluid, the apparatus comprising
a microfluidic chip in which first and second sets of parallel fluidic channels are provided under a transparent cover plate,
wherein the fluidic channels of the first set are arranged at a fixed spacing and connected to a first fluid supply channel at one of their ends and to a fluid removal channel at the other one of their ends,
wherein the fluidic channels of the second set are arranged at the fixed spacing and connected to a second fluid supply channel at one of their ends and to a fluid removal channel at the other one of their ends,
wherein the fluidic channels of the second set are arranged at a lateral offset of less than 45% of the fixed spacing with regard to the fluidic channels of the first set such that the fluidic channels of the first and second sets are arranged side by side.

12 . The apparatus of claim 11 further comprising
a light source directing coherent light directed onto the microfluidic chip such that light which passed through the fluidic channels of the first and second sets forms a diffraction pattern comprising intensity maxima, and
a light detector configured to measure two light intensities of two intensity maxima of a same order higher than zero.

13 . The apparatus of claim 11 further comprising a pressure controller configured to control pressures in the fluid supply and removal channels.

14 . The apparatus of claim 11 , wherein the fluidic channels of the first and second sets have a same width and a same depth measured in and perpendicular to a plane defined by the parallel fluidic channels, respectively.

15 . The apparatus of claim 14 , wherein
the same width of the nanochannels of the first and second sets is in a range from 100 nm to 20 μm, the same depth of the nanochannels of the first and second sets is in a range from 10 nm to 10 μm, and the fixed spacing of the nanochannels of the first and second sets is in a range from 500 nm to 100 μm.

16 . The apparatus of claim 11 , wherein the fluidic channels of the first and second sets are connected to a same fluid removal channel at the other one of their ends.

17 . The apparatus of claim 11 , wherein the microfluidic chip is reflective for the coherent light.

18 . The apparatus of claim 11 , wherein the microfluidic chip is transparent for the coherent light.

19 . The apparatus of claim 11 , wherein the light source directs the coherent light through a slit or a hole in a tilted mirror onto the channel plate, wherein the mirror deflects the diffraction pattern towards a camera of the light detector.

20 . A method of use of the apparatus of claim 11 , wherein a temporal development of material deposited on or removed from the inner surfaces of one or both sets of nanochannels is monitored by repeatedly directing the coherent light onto the first and second transparent gratings that are formed by the nanochannels and measuring the two light intensities of the two intensity maxima of the same order.

Assignees

• Max Planck Gesellschaft

Inventors

• Burg Thomas P
• Bassu Margherita
• Purr Foelke
• Dietzel Andreas

Classifications

• G02B5/1819

  Plural gratings positioned on the same surface, e.g. array of gratings (plural diffractive elements positioned sequentially along the optical path G02B27/4272) · CPC title

• G01N2021/4153

  Measuring the deflection of light in refractometers · CPC title

• G01N21/4133 Primary

  Refractometers, e.g. differential · CPC title

• B01L3/5027

  by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip · CPC title

• B01L2300/0867

  Multiple inlets and one sample wells, e.g. mixing, dilution · CPC title