Arrangement and method to apply diffusing wave spectroscopy to measure the properties of multi-phase systems, as well as the changes therein

• US 6,831,741 B1
• Filed: 08/22/2001
• Issued: 12/14/2004
• Est. Priority Date: 04/02/1998
• Status: Expired due to Fees

• Current Assignee: Stichting Nederlands Instituut Voor Zuivelonderzoek (Nizo)
• Original Assignee: Stichting Nederlands Instituut Voor Zuivelonderzoek (Nizo)
• Inventors: De Kruif, Cornelis Gijsbertus, Nishimura, Goro, Ten Grotenhuis, Erik, Weitz, David Allan, Yodh, Arjun Gaurang
• Primary Examiner(s): FULLER, RODNEY EVAN
• Application Number:
  US09/647,684
• Time in Patent Office: 1,210 Days
• Field of Search: 356/300, 356/301, 356/337, 356/338, 356/343
• US Class Current: 356/338
• CPC Class Codes: G01N 2011/008 optical properties
• CPC Class Codes: G01N 21/474 Details of optical heads therefor, e.g. using optical fibres
• CPC Class Codes: G01N 21/49 within a body or fluid
• CPC Class Codes: G01N 33/04 Dairy products

Abstract

Arrangement for measuring physico-chemical properties of liquid, such as solutions, dispersions and emulsions. The arrangement comprises a light source for producing and emitting light in the liquid, a detector for detecting said light after being scattered by said liquid, processing means arranged for receiving an output signal from said detector. The processing means is further arranged to calculate a maximum value of the mean square displacement <Δr_m²> from the autocorrelation function g⁽²⁾ as a function of time and the value of the property from said calculated maximum value of the mean square displacement <Δr_m²>.

Claims

1. Arrangement for measuring physico-chemical properties of liquid, such as solutions, dispersions and emulsions, comprising a light source (1) for producing and emitting light in the liquid (7), a detector for detecting said light after being scattered by said liquid (7), processing means arranged for receiving an output signal from said detector and for calculating the autocorrelation function g⁽²⁾ of said output signal from said detector characterized in that the processing means is arranged to calculate a maximum value of the mean square displacement <

Δ

r_m²>

from the autocorrelation function g⁽³⁾ as a function of time and the value of the physico-chemical property from said calculated maximum value of the mean square displacement <

Δ

r_m²>

.

2. Arrangement according to claim 1, characterized in that the physico-chemical property is the gelstrength G′

, characterized in the processing means is arranged to calculate the gelstrength G′

from said calculated maximum value of the mean square displacement <

Δ

r_m²>

using the following equation $G^{\mathrm{\prime <br><br>}}\approx <br><br>\frac{k_B<br><br>T}{\mathrm{\xi <br><br>}<br><br>〈<br><br>\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>r<br><br>\frac{2}{m}〉<br><br>}$

in which

k_b·

T=thermal energy of particles in the gel;

ξ

=size of a cluster in the gel.

3. Arrangement according to claim 1, comprising a machine (14) coupled to said processing means and wherein the processing means are arranged to compare said value of the physico-chemical property with a reference value of said property, and to activate the machine (14) upon the value reaching said reference value.

4. Arrangement according to claim 1, comprising a machine (14) for treating a gel, which is coupled to said processing means and wherein the processing means are arranged to compare said gelstrength G′

with a reference gelstrength (G_ref), and to activate the machine (14) upon the gelstrength G′

reaching said reference gelstrength for treating said gel.

5. Arrangement according to claim 1, comprising at least one detector fibre (8(1), 8(2), . . . ) arranged for detecting said light after being scattered by said liquid (7), processing means arranged for receiving an output signal from said at least one detector fibre and for calculating parameters with respect to said liquid (7) wherein any one of the at least one detector fibre (8(1), 8(2) . . . ) are located at predetermined locations with respect to each other.

6. Arrangement according to claim 5, wherein any one of the at least one detector fibre (8(1), 8(2) , . . . ) are single mode fibres.

7. Arrangement according to claim 5 wherein the source fibre (5) is a multimode fibre.

8. Arrangement according to claim 5 wherein the distances between any one of the at least one detector fibre (8(1), 8(2), . . . ) and the point of impinging of light on the liquid are larger than the mean free path of the light beam in the liquid (7).

9. Arrangement according to claim 5 wherein the light is directed to and the at least one detector fibre is immersed in a milk medium with an addition of a rennet.

10. Method according to claim 1 wherein the liquid is a milk medium with an addition of a rennet.

12. Arrangement according to claim 1, characterized in that the physico-chemical property is the gelstrength.

11. Arrangement for measuring physico-chemical properties of liquids, such as solutions, dispersions and emulsions, comprising a light source (1) for producing and emitting light in the liquid (7), a detector for detecting said light after being scattered by said liquid (7), processing means arranged for receiving an output signal from said detector and for calculating the autocorrelation function g⁽²⁾ of said output signal from said detector, characterized in that the processing means is arranged to determine the half decay time as a function of time of the autocorrelation function and to determine the value of the physico-chemical property using a predetermined relation between the half decay time and the autocorrelation function.

13. Method for measuring physico-chemical properties of liquids such as solutions, dispersions and emulsions, comprising the steps of:

producing a light beam (2)

emitting light in a liquid (7);

detecting said light after being scattered by said liquid (7);

converting the detected light in an electrical signal;

transmitting said electrical signal to processing means;

calculating the autocorrelation function g⁽²⁾ in the time- or the frequency domain of said electrical signal characterized in that said maximum value or the mean square displacement <

Δ

r_m²>

is calculated from the autocorrelation function g⁽²⁾τ

(r), or from g⁽²⁾(τ

) in a similar way, as a function of time and the value of the physico-chemical property is calculated from said calculated maximum value of the mean square displacement <

Δ

r_m²>

.

14. Method according to claim 13, wherein the physico-chemical property is the gelstrength G′

, characterized in that the gel-strength G′

is calculated from said calculated maximum value of the mean square displacement <

Δ

r_m²>

using the following equation;

$G^{\mathrm{\prime <br><br>}}\approx <br><br>\frac{k_B<br><br>T}{\mathrm{\xi <br><br>}<br><br>〈<br><br>\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>r<br><br>\frac{2}{m}〉<br><br>}$

in which,

k_b·

T=thermal energy of particles in the gel;

ξ

=size of a cluster in the gel.

15. Method according to claim 13, wherein the value of the physico-chemical property is compared with a reference value for controlling a machine for treating the liquid.

16. Method according to claim 13 wherein either a gelation, a flocculation or an aggregation process in the multi-phase system is monitored.

17. Method according to claim 13, comprising the steps of:

detecting said light after being scattered by said liquid (7) by means of at least one detector fibre (8(1), 8(2), . . . );

transmitting an output signal from said at least one detector fibre to processing means;

calculating parameters with respect to said liquid (7), wherein any one of the at least one detector fibre (8(1), 8(2), . . . ) are located at predetermined locations with respect to each other.

18. Method according to claim 17, wherein the distances between any one of the at least one detector fibre (8(1), 8(2), . . . ) and the point of impinging of light on the liquid are larger than the mean free path of the laser light in the liquid (7).

19. Method for measuring physico-chemical properties of liquids therein, such as solutions, dispersions and emulsions, comprising the steps of:

producing a light beam (2)

emitting light in a liquid (7);

detecting said light after being scattered by said liquid (7);

converting the detected light in an electrical signal;

transmitting said electrical signal to processing means;

calculating the autocorrelation function g⁽²⁾ of said electrical signal, characterized in that the half decay time is calculated as a function of time or the autocorrelation function, and the value of the physico-chemical property is determined using a predetermined relation between the half decay time and the autocorrelation function.

20. Method according to claim 19, wherein the physico-chemical property is the gelstrength.

21. Method according to claim 20 wherein said gelstrength G′

compared with a reference gelstrength (G_ref), and a machine (14) is activated upon the gelstrength G′

reaching said reference gelstrength for treating said gel.