DESC:OPTICAL SENSOR MODULE FOR ANALYZING LIQUID COMPOSITION

FIELD OF INVENTION
The present invention relates to an optical sensor module (OSM) used in an apparatus for analyzing a liquid composition by colorimetry and turbidimetry methods. The optical sensor module of the present invention executes spectroscopic analysis of light absorption and scattering by liquid mixer including the elements to be analyzed in a liquid composition. Advantageously, the optical sensor module has variable sample path length usage, single sample cell for both turbidity and colorimetry methods, high resolution and accuracy in turbidity measurement.

BACKGROUND OF INVENTION
Modernization in major areas and urban cities with concentrated human activity is currently causing significant water contamination, which is regarded one of the most serious environmental issues. As a result, it is essential to monitor and detect pollutants in water. There is a need for water quality testing devices that can analyse the essential key parameters. On-the-spot or in the lab to assess the water quality refers to the chemical and physical properties of water.

A range of products are currently used to monitor and measure water quality parameters that include turbidity, fluorometer and colorimeter. Each product contains separate light sources, optics, sample cell and photodetector for measuring key elements in water or liquid. The main drawback of current commercial products is their inability to cover most path lengths 0.1, 0.5, 10, 16, 20, 24, 50mm in single product.

IN202141033093A titled “Portable multi-parameter water quality analyser” filed by the same applicant ELICO limited, relates to an optical and ion selective electrode based measurement analyser to determine the concentration of essential analytical parameters as well as the turbidity of a water sample for Laboratory and field use. The analyser analysis multi-parameters in water based on principles/methods of potentiometric, electrical conductivity, colorimetric and nephelometric along with temperature measurement.

CN205749258U relates to a kind of multi-parameter water quality on-line checking pen, this utility model can detect COD, turbidity, colourity and four parameters of dissolvability solid amount (TDS) simultaneously, is compensated the testing result of ultraviolet absorption method. The water-quality is described by COD and turbidimetry methods.

CN207051182U relates to a kind of colorimetric measurement unit for online water quality detecting device including the cuvette with two different up and down light paths. Two groups of dual wavelength optical systems, the incidence end of cuvette is arranged in up and down, correspond to two different light paths of cuvette respectively;With two groups of light source receiving modules, two groups of dual wavelength optical systems are corresponded respectively to;A part of light source of the emergent light of each group of dual wavelength optical system is received by the light source receiving module of respective sets by cuvette and not received and another part light source by cuvette by the light source receiving module of respective sets.

WO2006043900A1 describes about testing system for continuous sampling and testing of effluent at a water treatment plant, the system comprising: a sampling system to collect samples of the effluent; a monitoring system (40) connected to the sampling system, for measuring environmental parameters of the samples, the monitoring system comprising: a first analysis chamber (41) for measuring environmental parameters of at least two selected from the group consisting of: pH, oxidation reduction potential (ORP) value for state of reduction oxidation (Redox), conductivity value for total dissolved solids (TDS), dissolved oxygen (DO), turbidity (Tu) value for suspended solid (SS) and temperature (T); a second analysis chamber (50) for measuring the concentration of anions in the samples using a plurality of ion selective electrodes (ISEs); and a third analysis chamber (61) for measuring the concentration of heavy metals in the samples using anode stripping voltammetry (ASV); and a control system to control the collection of samples by the sampling system, to control washing and rinsing of the analysis chambers, and to record the measurements obtained by the monitoring system.

JP4487197B2 relates to turbidity / colorimeter that optically determine turbidity and chromaticity based on the amount of transmitted light and scattered light. The turbidity method includes a transmitted light method, a scattered light method, a surface scattered light method, and a transmitted scattered light method. In particular, the transmission scattering method that optically obtains turbidity by the ratio of the amount of transmitted light and scattered light. The light method can measure from low turbidity to high turbidity.

CN111189804A provides a turbidity detector and a detection method, wherein a circuit module is connected with an optical module; the optical module is arranged at the first end of the shell and is detachably connected with the first end of the shell; the receiving unit and the transmitting unit are respectively communicated with the outside of the shell through the light guide columns, the transmitting unit emits detection light according to the detection control instruction, and the receiving unit receives the detection light and transmits a received light signal to the circuit module; the control unit is respectively connected with the receiving unit and the transmitting unit through the data transmission processing unit; the control unit sends a detection control instruction to the transmitting unit; the control unit obtains the received light signal through the receiving unit and calculates to obtain water quality turbidity data.

WO2012007542A1 relates to a method and apparatus for determining at least the concentration or turbidity of a dispersed phase suspended in a fluid, comprising the emission of a light beam into a sample of the fluid and the detection of scattered light from the fluid sample.

Non-Patent literature titled “Low-cost portable turbidimeter for processes” published in Journal of Instrumentation (JINST) relates to the scattering of light by particles that are suspended in a liquid. An infrared LED was used as light emitter, and an infrared phototransistor as light receiver. The signal processing control unit was developed with the Arduino Uno platform. The calibration of the turbidimeter was done by means of a comparative test in triplicate, using as reference the commercial turbidimeter 2100P, HACH®. The turbidimeter was able to perform analysis in the range of 100 to 1000 NTU, presenting an innovation character given its portability and computer communication via USB.

Furthermore, currently various optical modules are used to measure and monitor liquid or water quality parameters. Each module has its own optical sensing unit for measurement of color concentration and turbidity of liquid sample.

Accordingly, there exists a need for a dual view configuration and different optical path length of optical sensor module for instantly measuring the critical liquid or water quality parameters.

OBJECTS OF INVENTION
One or more of the problems of the conventional prior art may be overcome by various embodiments of the system and method of the present invention.

It is the primary object of the present invention to provide an optical sensor module (OSM) used in an apparatus for analyzing a liquid composition by colorimetry and turbidimetry methods that supports to assess liquid or water quality parameters without the usage of multiple products and overcome the constraints of traditional methods.

It is another object of the present invention to provide an optical sensor module that executes spectroscopic analysis of light absorption and scattering by liquid mixer including the elements to be analyzed in a liquid composition.

It is another object of the present invention to provide an optical sensor module that integrates colorimetric and turbidity to measure the concentration of chemical elements and turbidity.

It is another object of the present invention to provide a single optical sensor module for dual view configuration for measuring the colour concentration and turbidity of the liquid sample.

It is another object of the present invention, wherein the optical sensor module analyses the scattered light at 90 degrees and transmitted light at 180 degrees for turbidity measurement.

It is another object of the present invention, wherein the optical sensor module has variable sample path length usage, single sample cell for both turbidity and colorimetry methods, high resolution and accuracy in turbidity measurement.

It is another object of the present invention, wherein the optical sensor module achieves high resolution and accuracy in the range of 0-200 NTU, and low resolution and accuracy in the range of 0-1000 NTU.

SUMMARY OF INVENTION
Thus according to the basic aspect of the present invention, there is provided an optical sensor module for analyzing liquid composition, comprising of:
a colorimetric sub module; and
a turbidity sub module to measure the turbidity in two ways;
characterized in that, said optical sensor module provides dual view configuration and various optical path lengths for instantly measuring the critical liquid quality parameters and chemical element concentration,
wherein the colorimetric sub module comprises of:
a light source to illuminate a test sample;
an optical lens to collimate the light received from the light source;
a filter wheel;
an optimized lens;
a sample cuvette containing a test sample with variable path lengths;
a photodetector for detecting the light passed through the test sample; and
an optical lens for focusing light onto the photodetector,
wherein one of the turbidity sub module comprises of:
a light source along with collimating lens;
dual photodetectors to detect the scattered light at 90 degrees and transmitted light at 180 degrees;
an optical lens for focusing light onto one of the photodetector; and
another optical lens which collects and focus transmitted light from sample path onto the other photodetector,
wherein the other turbidity sub module comprises of:
a light source;
an orthogonal photodetector for detection of orthogonal scattered light; and
an optical lens which collects and focus scattered light from sample path onto the orthogonal photodetector.

It is another aspect of the present invention, wherein the filter wheel consists of optical filters, a stepper motor and an optical switch for selecting desired wavelength for each test sample analysis.

It is another aspect of the present invention, wherein the optimized lens covers various optical path lengths of 0 to 50 mm for measuring the concentration of analytical parameters of the test sample.

It is another aspect of the present invention, wherein the sample cuvette which is used in both the colorimetric sub module and turbidity sub module accommodates multiple path lengths of 0 to 50 mm for measuring the concentration of analytical parameters of the test sample.

It is another aspect of the present invention, wherein in the colorimetric sub module, when the light from the light source illuminates the test sample in the sample cuvette, the transmitted light is detected by the photodetector which is placed in axial position to the sample cuvette.

It is another aspect of the present invention, wherein in the turbidity sub module when the light from the light source illuminates the test sample in the sample cuvette, one of the photodetector measures scattered light through one of the optical lens and the other photodetector measures transmitted light through the other optical lens, both the scattered light and transmitted light are used for measurement of turbidity.

It is another aspect of the present invention, wherein the turbidity sub module performs simultaneous detection of scattered light in axial and perpendicular light paths thereby achieving a 0-200 NTU range with high resolution and accuracy and a 0-1000 NTU range with lower resolution and high accuracy.

It is another aspect of the present invention, wherein the light source in the colorimetric sub module is a white LED source and the light source in the turbidity sub module is an infrared LED source.

BRIEF DESCRIPTION OF DRAWINGS
Figure 1: illustrates cross sectional view of optical sensor module with dual-photodetector for colorimetry and turbidity measurement methods according to the present invention.
Figure 2: illustrates cross sectional view of optical sensor module for colorimetry method according to the present invention.
Figure 3: illustrates cross sectional view of optical sensor module along with dual-photodetector to measure turbidity according to the present invention.
Figure 4: illustrates cross sectional view of optical sensor module with single photodetector for turbidity measurement method according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO ACCOMPANYING DRAWINGS
The present invention as herein described relates to a simple, optical sensor module (OSM) for analyzing a liquid composition by colorimetry and turbidimetry methods that supports to assess liquid or water quality parameters on the spot without the usage of multiple products and overcome the constraints of traditional methods. The present invention provides dual view configuration and different optical path length of optical sensing module for instantly measuring the critical liquid or water quality parameters. The present invention is advantageous over existing products in terms of universal module for various optical path length, dual light detection, high resolution and applicability.

Referring to Figures 1 to 4, the optical sensor module [300] for analyzing liquid composition comprises of a colorimetric sub module [100] and a turbidity sub module [200 and 250] to measure the turbidity in two ways. The colorimetric sub module [100] comprises of a light source [102] to illuminate a test sample, an optical lens [104] to collimate the light receives from the light source [102], a filter wheel [108], an optimized lens [110], a sample cuvette [112] containing a test sample with variable path lengths between 0-50mm, a photodetector [114A] for detecting the light passed through the test sample, and an optical lens [104A] for focusing light onto the photodetector [114A] after said light passes through the filter wheel [108] and test sample. The filter wheel [108] consists of a set of optical filters [106] and an optical switch for selecting desired wavelength which supports for analyzing the most essential multi-parameters. The filter wheel [108] is connected to a geared stepper motor which is used to determine the homing position and filter wheel positions for each sample analysis. Each optical filter [106] is chosen and held stationary during the testing of the target sample. The colorimetric sub module [100] is a light-sensitive module used to assess the concentration of liquid sample by transmittance (%T) and absorbance (Abs.). The optimized lens [110] is used for multiple path lengths without losing of light throughput. The optical sensor module executes spectroscopic analysis of light absorption and scattering by liquid mixer including the elements to be analyzed in a liquid composition.

In an embodiment, the light source [102] is a white light-emitting diode (LED) source.

Referring to Figures 1 and 3, the turbidity sub module [200] comprises of a light source [202] along with collimating lens; dual photodetectors [114A and 114B] to detect the scattered light at 90 degrees and transmitted light at 180 degrees; an optical lens [104A] for focusing light onto the photodetector [114A]; an optical lens [104B] which collects and focus transmitted light from sample path onto the photodetector [114B].

Referring to Figures 1 and 4, the turbidity sub module [250] comprises of a light source [202]; an orthogonal photodetector [114A] for detection of orthogonal scattered light; an optical lens [104A] which collects and focus scattered light from sample path onto the photodetector [114A].

The sample cuvette [112] used in both colorimetric sub module [100] and turbidity sub module [200 and 250] accommodates multiple path lengths between 0 to 50mm (0.1, 0.5, 10, 16, 20, 24, 50mm) for measuring the different concentration ranges of test samples.

In an embodiment, the light source [202] is an infrared light-emitting diode (LED) source.

In an embodiment, the optical sensor module [300] provides centralized and different optical path lengths between the range 0 to 50mm for rectangle, square and round shaped sample cuvette [112] to measure the concentration of liquid.

Working:
When the optical sensor module [100] is switched on, in the colorimetric sub module [100], the light from the light source [102] passes through the optical filter [106], optimized lens [110] and falls on the test sample in the sample cuvette [112], said test sample absorbs the light based on sample characteristics. In an aspect, the test sample absorbs some light and remaining light is sent to the photodetector [114A] through the optical lens [104A]. The transmitted light is detected by the photodetector [114A] which is placed in axial position to the sample cuvette [112].

When the optical sensor module [100] is switched on, in the turbidity sub module [200], the light from the light source [202] illuminates the test sample in the sample cuvette [112], the orthogonal photodetector [114A] measures the light scattered at 90 degrees through the optical lens [104A] and axial photodetector [114B] measures the light transmitted at 180 degrees through the optical lens [104B], both the lights are used for measurement of turbidity. The turbidity measurement sub module [200 and 250] performs simultaneous detection of scattered light in axial and perpendicular light paths thereby achieving a 0-200 NTU range with high resolution and accuracy and a 0-1000 NTU range with lower resolution and high accuracy. The dual detection method increases the turbidity measurement range and accuracy as well. In an aspect, the turbidity sub module [200 and 250] comprises of 850nm infrared LED source to illuminate the liquid sample.

The combination of two detection modules into a single optical sensing module opens up new possibilities for analyzing water quality parameters and other chemical and physical parameters, it has a great potential as a stand-alone module for supporting to laboratory equipment and field measurement instruments.

The optical sensor module according to the present invention is used in liquid or water analyzers for analyzing liquid samples that include water, beverages, dairy products, chemicals and pharmaceuticals composition.

Test results:
The optical sensor module is tested with turbidity method especially in orthogonal mode (scattering light detection mode). In this turbidity method, 24mm of sample path length is used for measurement of turbidity. The measured values against standard turbidity solution are tabulated in below Table-1 in the range of 0-200 NTU. The accuracy of the measurement is ± 2% as per tested/measured values.

TURBIDITY FUNCTIONAL TEST: RANGE 0-200 NTU
Standard solution value (NTU) Measured Value (NTU)
200 197.9
100 99.1
50 49.5
10 9.8
5 5.06
2 2.01
1 0.98
0.5 0.51
0 0.00
Acceptance Limit of the Product: Standard value ? 2 %
Table -1:

Technical advancements:
• Combination of two detection modules into a single optical sensing module.
• Determines the quality of liquid sample with the two measurement methods of colorimetry and turbidity.
• Dual view configuration and different optical path length of optical sensing module for instantly measuring the critical liquid or water quality parameters and chemical element concentration in the lab and field.
• Dual light detection: Analyses scattered light at 90 degrees and transmitted light at 180 degrees for turbidity measurement to achieve high resolution and accuracy in the range of 0-200 NTU, and low resolution and accuracy in the range of 0-1000 NTU.
,CLAIMS:WE CLAIM:
1. An optical sensor module [300] for analyzing liquid composition, comprising of:
a colorimetric sub module [100]; and
a turbidity sub module [200 and 250] to measure the turbidity in two ways;
characterized in that, said optical sensor module [300] provides dual view configuration and various optical path lengths for instantly measuring the critical liquid quality parameters and chemical element concentration,
wherein the colorimetric sub module [100] comprises of:
a light source [102] to illuminate a test sample;
an optical lens [104] to collimate the light received from the light source [102];
a filter wheel [108];
an optimized lens [110];
a sample cuvette [112] containing a test sample with variable path lengths;
a photodetector [114] for detecting the light passed through the test sample; and
an optical lens [104A] for focusing light onto the photodetector [114A],
wherein the turbidity sub module [200] comprises of:
a light source [202] along with collimating lens;
dual photodetectors [114A and 114B] to detect the scattered light at 90 degrees and transmitted light at 180 degrees;
an optical lens [104A] for focusing light onto the photodetector [114A]; and
an optical lens [104B] which collects and focus transmitted light from sample path onto the photodetector [114B],
wherein the turbidity sub module [250] comprises of:
a light source [202];
an orthogonal photodetector [114A] for detection of orthogonal scattered light; and
an optical lens [104A] which collects and focus scattered light from sample path onto the photodetector [114A].

2. The optical sensor module [300] as claimed in claim 1, wherein the filter wheel [108] consists of optical filters [106], a stepper motor and an optical switch for selecting desired wavelength for each test sample analysis.

3. The optical sensor module [300] as claimed in claim 1, wherein the optimized lens [110] covers various optical path lengths of 0 to 50 mm for measuring the concentration of analytical parameters of the test sample.

4. The optical sensor module [300] as claimed in claim 1, wherein the sample cuvette [112] which is used in both the colorimetric sub module [100] and turbidity sub module [200 and 250] accommodates multiple path lengths of 0 to 50 mm for measuring the concentration of analytical parameters of the test sample.

5. The optical sensor module [300] as claimed in claim 1, wherein in the colorimetric sub module [100], when the light from the light source [202] illuminates the test sample in the sample cuvette [112], the transmitted light is detected by the photodetector [114A] which is placed in axial position to the sample cuvette [112].

6. The optical sensor module [300] as claimed in claim 1, wherein in the turbidity sub module [200] when the light from the light source [202] illuminates the test sample in the sample cuvette [112], the photodetector [114A] measures scattered light through the optical lens [104A] and photodetector [114B] measures transmitted light through the optical lens [104B] both the scattered light and transmitted light are used for measurement of turbidity.

7. The optical sensor module [300] as claimed in claim 1, wherein the turbidity sub module [200 and 250] performs simultaneous detection of scattered light in axial and perpendicular light paths thereby achieving a 0-200 NTU range with high resolution and accuracy and a 0-1000 NTU range with lower resolution and high accuracy.

8. The optical sensor module [300] as claimed in claim 1, wherein the light source [102] is a white LED source and the light source [202] is an infrared LED source.