A device and method to identify cooking oils by cuvette structured microstrip patch antenna sensor

Abstract

A device and method to identify cooking oils by cuvette structured microstrip patch antenna sensor are disclosed. The device (100) comprises of: a cuvette structured microstrip patch antenna sensor (50) which is connected with a network analyser (20) through a SMA connector / cable (10). A high frequency cable (30) is connected to the single port of said network analyser (20). The sensor (50) comprises of a top substrate (1) which is formed of radiating copper patch, a bottom copper substrate (3) which is grounded and a cavity (2) which is provided between top and bottom substrates (1,3) made of acrylic layers to fill the liquid under test. The cooking oils including gingelly oil, coconut oil and groundnut oil are classified as refined oil and cold pressed oil based on the measured return loss values depending upon the threshold value.

Description

FIELD OF THE INVENTIONThe present invention relates to the field of sensing devices in food quality and analysis to study characteristics of edible oils, and specifically relates to a sensing device for testing the quality and classification of cooking oil. More particularly, the present invention relates to a device and method to identify and classify cooking oils by cuvette structured microstrip patch antenna which is designed and fabricated to classify the edible oils by identifying their permittivity in terms of antennas return loss and resonance frequency.BACKGROUND OF THE INVENTIONThere are several methods for testing the quality and classification of cooking oil. Simple methods such as identifying the taste, smell and color of the cooking oil are excessively subjective, inaccurate and too time consuming. Other schemes involve identifying the smoke point or viscosity of the cooking oil. Again, while these measurements are fairly simple, they are dependent on factors such as cooking oil type and cooking oil debris, to be considered universally reliable.Nowadays, in food industry, eatable items are major reasons for digestive health problems in the society due to the adulteration and contamination of food. The contamination of food items is due to the addition of low quality ingredients with standard food and other eatables. Mixing of water with milk, addition of similar colored oil with edible oils are few examples for this case. This leads to health problem in consumer and in turn affects the business of standard food industries. The accurate measurement of contamination in food and other eatable items is very important. As per Bureau of Indian Standards (BIS, IS 14309: 1995, Reaffirmed 2001), the blended edible oil shall be free from argemone oil, hydrocyanic oil,mineral oil and other adulterants, such as kusum oil. castor oil, neem oil, karanja oil, animal fat and tricresyl phosphate, when tested according to the methods prescribed in IS 548. Pood Safety and Standards Authority of India (FSSAI), has introduced restrictions on reusing cooking oil. The reheating and reusing of oil should be avoided. Further, FSSAI also restricted that the cooking oil should not be reused if the total polar compounds in the oil exceed 25%. Hence methods to identify contamination, adulteration and classification of oils are the need of the society.One of the prior art patent US581873IA, discloses a method and apparatus for measuring quality of frying / cooking oil. This oil quality sensor simultaneously monitors the change in capacitance and optical transmission of the oil. Large surface area, multiple parallel plates are used to measure the capacitance. A 675 nm laser diode and photodiode are used to measure the transmittance of the oil. A sensor is programmed to monitor the oil condition and indicate whether the oil has to be replaced or not. Multi- plated parallel plate capacitor and laser diode are required for this experiment, whereas the present invention is based on cuvette patch antenna sensor and the laser diode is not used in the technique of the present invention.Another prior art patent RU2324I77C2, discloses an apparatus for testing liquid quality in particular edible oil cooking facility. The apparatus for testing edible oil quality is based on capacitive sensor technique. The sensor is designed with a pair of electrodes to measure the change in permittivity of the liquid. The sensor is to be immersed in liquid to take the measurements. A pair of electrodes are required for this measurement, whereas, the present invention is based on antenna structure not based on capacitance measurement system.Yet another prior art patent US20I80156748 Al, discloses a portable device for measuring dielectric and / or magnetic characteristics of samples. The portable device is used to measure dielectric / magnetic characteristics of samples and electromagnetic wave is made to pass through the cavity having sample. Here, the RF signal has to be passed through the sample holder of a detector and a computer toprocess the RF signal, whereas in the present invention, the device is used to measure the liquid quality by obtaining the resonant frequency and return loss and the electromagnetic wave is made to radiate from the antenna whose cavity is filled with liquid under test. The RF source is present to deliver the electromagnetic wave to microstrip antenna.Another prior art, IN201921006284 A, discloses an apparatus for detecting adulteration in petroleum and non-petroleum oils. Here the microstrip resonator with shielded conductive box is required and the microstrip resonator is provided with stacked multi ring resonator with First substrate of 1.575 mm and second substrate of 1.6 mm. The drawback of the existing prior art shows that the conductor box is provided with hallow rectangular structure having an open slot at top and bottom of the box and the distance between first and second substrate is fixed as }J2. whereas in the present invention, the microstrip patch sensor is formed of acrylic dielectric material and a gap / cavity is provided between acrylic dielectric materials for injecting liquid. In the present invention, the conductor box is not used. However, microstrip patch is made up of copper for both patch and ground. The length of the airgap / cavity is 3mm in the microstrip patch sensor.There is a need fora novel method and device of the present invention to identify quality of cooking oil by cuvette structured microstrip patch antenna sensor which is designed at 2.4 GHz and fabricated by using acrylic material. Moreover, the temperature of the oil under test can be varied in the range of 35 to 105 degrees Celsius, by a Peltier element attached to the antenna sensor. The oil under test which is filled in the microstrip patch antenna acts as a dielectric material in the present invention and does not have contact with the copper conductors, leading to better use and longer life of the sensor. Hence, in the present invention there is no requirement for a separate testing jar or container is required in the sensor system which has a dual property of sensor and antenna. The antenna may also be used for transmission and reception of electromagnetic waves at 2.4 GHz.OBJECT OF THE INVENTIONAccordingly, the primary object of the present invention is to provide a novel method and device to identify and classify different cooking oils by cuvette structured microstrip patch antenna sensor which is used to determine the liquid quality by obtaining the resonant frequency and return loss.It is one object of the present invention to provide a cuvette structured microstrip patch antenna which is designed at 2.4 GHz and fabricated by using acrylic material.It is another object of the present invention to provide a cavity which is provided between top and bottom substrates made of acrylic layers to fill the liquid under test.It is further object of the present invention to provide a top substrate which is formed of radiating copper patch and bottom substrate is grounded.It is yet another object of the present invention to provide the edible oils under test which is filled in the microstrip patch antenna, which acts as a dielectric material in the present invention, thereby no separate testing jar or container is required in the sensor system of the present invention.It is another object of the present invention to provide temperature change in the oil under test by a Peltier element attached to the antenna structure.It is another object of the present invention to provide the device which has a dual property of sensor and antenna, where the antenna is also used for transmission and reception of electromagnetic waves at 2.4 GHz.It is further object of the present invention to provide the sensor device which makes the electromagnetic wave to radiate from the antenna whose cavity is filled with liquid under test, and the RF source is provided to deliver the electromagnetic wave to microstrip antenna.SUMMARY OF THE INVENTIONAccording to the basic aspects of the present invention, the cuvette structured microstrip patch sensor is realized as a multiple dielectric cavity using acrylic sheet and oil. A gap / cavity is provided between acrylic layers to fill cooking oils including refined coconut oil, cold pressed coconut oil, refined gingelly oil, cold pressed gingelly oil, refined groundnut oil and cold pressed groundnut oil. Through the present invention, return loss is measured, which depends on the overall dielectric constant of the patch antenna. Due to the change in the dielectric constant of the oil sample in the cavity, a change in resonant frequency is observed. Arrangement for varying the temperature of the oil sample is also provided. Moreover, the sensor system of the present invention can be used as an antenna for transmission and reception of EM waves at 2.4 GHz.According to one aspect of the present invention, there is provided a device for identifying cooking oils by cuvette structured microstrip patch antenna sensor which measures the liquid quality by obtaining the resonant frequency and return loss, comprising: a SMA connector / cable, a network analyzer, a high frequency cable connected to the single port of said network analyzer, a calibrating kit to calibrate said network analyzer and a cuvette structured microstrip patch antenna sensor.According to another aspect of the present invention, the said cuvette structured microstrip patch antenna sensor which comprises of: a top substrate which is formed of radiating copper patch, a bottom copper substrate which is grounded and a cavity which is provided between top and bottom substrates made of acrylic layers to fill the liquid under test. The cuvette structured microstrip patch antenna is designed at 2.4 GHz, wherein said top and bottom substrates or layers are provided with a spacing of 2.5 mm therebetween. The dielectric constants of substrates made of acrylic materials and air gap are 3.7 and I respectively. The acrylic materials used for the substrates provide low dielectric constant which varies from 1.9 to 3.7, which provides higher gain and directivity. A Peltier heating element is attachedwith the ground plane copper conductor of the antenna sensor. The edible cooking oils under test are filled between radiating patch plane and ground plane of the microstrip patch antenna sensor, which also acts as a dielectric material, whereby no separate testing jar / container is required.According to another aspect of the present invention, the said SMA connector / cable is soldered through 20 mm length cable and the network analyzer with display is connected with said cuvette structured microstrip patch antenna sensor through said SMA connector / cable. The conductor used in patch antennas is made up of two copper foils having thickness of 0.035 mm. A Peltier unit is fixed on one side of the said cuvette structured microstrip patch antenna sensor for temperature variation and a digital thermometer and a power supply provided for the temperature analysis.According to further aspect of the present invention, wherein, said cuvette structured microstrip patch antenna sensor device provides a dual property of both sensor and antenna, where the antenna is used for transmission and reception of electromagnetic waves at 2.4 GHz.According to another aspect of the present invention, the patch width and length of microstrip patch antenna sensor are 48 mm and 40 mm respectively, the length and width of the feed line are 20 mm and 4 mm respectively, and the inset feed is used for feeding technique.wherein, the return loss of -8.76 dB for refined coconut oil and -8.3 dB for cold pressed coconut oil are obtained at 2.27 and 2.25 GHz respectively, and the return loss of -9.05 dB and -8.44 dB is obtained at 2.275 GHz for refined and cold pressed groundnut oil respectively, and the return loss of-8.42 dB and -8.7 dB for refined and cold pressed gingelly oil are obtained at 2.27 GHz respectively; andwherein the VSWR is calculated as 2.24, 2.05 and 2.27 for refined coconut oil,refined groundnut oil, and refined gingelly oil respectively and the VSWR is calculated as 2.29, 2.25 and 2.14 for cold pressed coconut oil, cold pressed groundnut oil and cold pressed gingelly oil respectively.According to yet another aspect of the present invention, there is provided method (200) for identifying cooking oils by cuvette structured microstrip patch antenna sensor which measures the liquid quality by obtaining the resonant frequency and return loss, comprising the steps of: providing the device having a cable and antenna analyzer, a high frequency cable, calibrating kit and the patch sensor, providing a cuvette structured microstrip patch antenna sensor which comprises of: forming a top substrate which is formed of radiating copper patch; forming of a bottom copper substrate which is grounded; and forming a cavity which is provided between top and bottom substrates made of acrylic materials to fill the liquid under test, connecting a high frequency cable to the single port of the network analyzer and calibrating by the calibrating kit and connecting said patch antenna sensor through cable. The edible cooking oils / liquid under test is filled in the cavity between radiating patch plane and ground plane of the microstrip patch antenna sensor, which acts as a dielectric material, whereby no separate testing jar / container is required. The return loss for the microstrip patch sensor is measured without liquid at 2.4 GHz and the return loss for the microstrip patch sensor with oil under test is also measured. The average value of return loss is fixed as a threshold value and the oil is classified as refined oil if return loss is lesser than the threshold and the oil is classified as cold pressed if return loss is greater than the threshold, in the case of coconut and ground nut cooking oils. The oil is classified as refined oil if return loss is above the threshold conditions and the oil is classified as cold pressed oil if return loss is below threshold value, in case of gingelly oil, wherein, said threshold values are fixed as -8.53 dB, -8.745 dB and -8.56 dB for coconut, ground nut and gingelly oils, respectively.BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGSThe above set forth and other features of the invention are made more apparent in the ensuring detailed description of the invention, when read in conjunction with the accompanying drawings, wherein:Fig. 1 illustrates an acrylic based multi-cavity model of cuvette structured microstrip patch antenna sensor, according to the present invention.Fig. 2 illustrates a front view of the microstrip patch antenna sensor without connector, according to the present invention.Fig. 3a & 3b illustrates a side view and detailed side view of the microstrip patch antenna sensor, according to the present invention.Fig. 4a & 4b illustrates a front side isometric view and a rear isometric view of the microstrip patch antenna sensor according to the present inventionFig. 5a & 5b illustrates the top and bottom view of the microstrip patch antenna sensor respectively, according to the present invention.Fig. 6 illustrates a side view of the microstrip patch sensor including the connector and Peltier element according to the present invention.Fig. 6a illustrates a flow diagram of a method for identification of cooking oils using a cuvette structured microstrip patch antenna sensor, according to the present invention.Fig. 7 illustrates a block diagram of the microstrip patch sensing device with network analyzer and temperature variation set up, according to the present invention.Fig. 8 illustrates a front isometric view of the microstrip patch sensor fixed with Peltier unit and connecting cable according to the present invention.Fig. 9a and 9b illustrates a graphical representation of the resonant frequency and return loss of the microstrip patch sensor for cold pressed and refined gingelly oils under different temperatures, according to the present invention.DETAILED DESCRIPTION OF INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGSWith reference to the above figures 1-4, the invention is illustrated as applied to, a cuvette structured microstrip patch antenna sensor, according to the present invention. The dual purpose microstrip patch sensor device is designed and developed for edible oil classification and quality measurement. Microstrip patch sensor is designed and simulated at 2.4 GHz, which comprises a top, and bottom substrate layers made of acrylic materials used for developing multi dielectric cavity due to its low dielectric constant and transparency, which also helps in volumetric analysis of the oil to be tested.In one embodiment of the present invention, a gap / cavity is provided between top and bottom substrates made of acrylic materials in the microstrip patch sensor. Using Acrylic and air, multi dielectric cavity model is designed and simulated. The dielectric constants of Acrylic and air are 3.7 and 1 respectively. The top and bottom layers are Acrylic with 2.5mm spacing provided in between them. Advanced Design System (ADS) software is used for design. Microstrip patch sensor is designat 2.4GHz.In another embodiment of the present invention, there is provided a multicavity model which is designed in cuvette structure with two layers of acrylic sheet with thickness 2.5mm. The model is shown in Figure 1. The layer I and layer 2 are bottom and top plates / substrates of the cuvette respectively. The middle layer of the antenna is a cavity designed such a way that the cooking oil sample can be filled. Layout is generated using schematic of microstrip patch antenna and its patch width and Length48mm and 40mm respectively. The length and width of the feed line are 20mm and 4mm respectively. The feeding technique, which is used in this method, is inset feed.Furthermore, the acrylic materials have low dielectric constant which leads to higher gain and directivity, the dielectric constant varies from 1.9 to 3.7, which is also transparent and adapted for liquid application. The acrylic sheet of 2.5 mm thickness is used as a substrate. Normally copper or lead coated copper is used as a conductor in patch antennas and two copper foils of thickness 0.035 mm are used. Front view of microstrip patch antenna sensor is shown in Figure 2. Side view and detailed side view of the microstrip patch sensor are shown in Figure 3a and Figure 3b respectively. A front side isometric view and a rear isometric view of the microstrip patch antenna sensor are shown in Figure 4a and Figure 4b respectively. The width and length of the patch antenna sensor are 48 mm and 40 mm respectively.With reference to the figures 5a and 5b, the invention is illustrated as applied to, a top and bottom view of the fabricated patch antenna sensor, according to the present invention. The side view of the microstrip patch antenna sensor including connector and Peltier element is shown in Figure 6. The prototype is fabricated with cavity (61*61 *7.5 mm), copper foil thickness of 0.035 mm, two layers of acrylic sheet along with third substrate (oil under test). In this model, the SMA connector is soldered through 20 mm length cable.With reference to the figure 6a, the invention is illustrated as applied to, a method for identification of cooking oils using a cuvette structured microstrip patch antenna sensor, according to the present invention. The method comprising the steps of: providing the complete experimental setup having a cable and antenna analyzer, a high frequency cable, calibrating kit and the patch sensor. First, the HF cable is connected to the single port of the analyzer and calibrated by the calibrating kit. After calibration is completed, the patch antenna sensor is connected through cable. Liquid under test is filled in the cavity of the microstrip patch sensor. Refined Coconut oil, cold pressed coconut oil, refined gingelly oil, cold pressed gingelly oil, refined groundnut oil and cold pressed groundnut oil are considered for this analysis. Sn,return loss are measured for the microstrip patch sensor without liquid at 2.4 GHz. Similarly, return loss is measured for the microstrip patch sensor with oil under lest. The measured values of return loss, VSWR and resonant frequency for refined and cold pressed oils are compared and provided in the table 1.Table 1.The return loss of -8.76 dB for refined coconut oil and -8.3 dB for cold pressed coconut oil are measured at 2.27 and 2.25 GHz respectively. Similarly, return loss of -9.05 dB and -8.44 dB is obtained at 2.275 GHz for refined and cold pressed groundnut oil respectively. The experiment is repeated for gingelly oil, which provides return loss of -8.42 dB and -8.7 dB for refined and cold pressed gingelly oil at 2.27 GHz. The calculated VSWR for refined coconut oil, refined groundnut oil, and refined gingelly oil are 2.24, 2.05 and 2.27 respectively. A VSWR of 2.29, 2.25 and 2.14 are obtained for cold pressed coconut oil, cold pressed groundnut oil and cold pressed gingelly oil respectively. A difference in return loss values, VSWR and resonant frequency are observed for the cold pressed oil and refined oils, using the developed antenna sensor. The difference in VSWR and resonant frequency is not significant. However, the difference in return loss parameter is predominant. Hence,this factor can be used for the discrimination of the cold pressed and refined oils. The average value of return loss may be fixed as a threshold and the oil which provides return loss less than the threshold, is classified as refined oil else it is cold pressed, in the case of coconut and ground nut oils. In the case of gingelly oil, above threshold conditions indicate refined oil and below threshold value corresponds to cold pressed. The threshold values (average) can be fixed as -8.53dB, -8.745dB and -8.56dB for coconut, ground nut and gingelly oils, respectively. The behaviour of the gingelly oil may be attributed to the refining process and the electrical properties of gingelly oil.The oil under lest is filled in the gap between radiating patch plane and ground plane of the microstrip patch antenna sensor along with acrylic material. This forms a secondary dielectric material. The classification of different cooking oils is determined by simple microstrip patch antenna sensor. Moreover, the structure also acts as a transmitting and receiving antenna for 2.4 GHz wireless applications.With reference to the figure 7, the invention is illustrated as applied to, a block diagram of the microstrip patch sensing device with network analyzer and temperature variation set up, according to the present invention. The sensing device arrangement also comprises of a thermoelectric cooling (TEC) module or Peltier Module, which is a semiconductor-based electronic component that functions as a small heat pump. By applying the DC power source to the Peltier unit, heat will be transferred from one side of the module to the other. The effect of temperature on the oil quality measurement by microstrip patch sensor is analyzed by fixing a Peltier module on the ground side of the sensor. A DC power supply (0 -12 V) and a digital thermometer are required for this analysis, in addition to the network analyzer. A front isometric view of the microstrip patch sensor fitted with Peltier module and connecting cable is provided in the Figure.8.Measurement of resonant frequency, return loss, Voltage Standing Wave Ratio (VSWR) and impedance for Microstrip patch sensor at various temperatures:The characteristics of microstrip cavity sensor fixed with Peltier unit are analyzed in this experiment. Initially, no oil (air) is filled in the microstrip patch sensor. The sensor is connected with the network analyzer by using SMA connector. The apparatus used for this analysis arei) Microstrip patch sensor with Peltier unitii) ZVH8- Cable and antenna analyzeriii) DC power supplyiv) Digital ThermometerPower supply is provided to the Peltier unit and sensing terminal of the digital thermometer is inserted into the microstrip patch sensor cavity. The network analyzer is calibrated for the frequency range of 1 GHz to 4 GHz before measurement.Measured parameters for Peltier mounted Microstrip patch sensor without cooking oil at room temperature.Return loss, resonant frequency, VSWR and impedance of Peltier mounted microstrip patch sensor are measured without cooking oil (air) at room temperature. Return loss and resonant frequency are measured as 2.575 GHz and -8.45 dB respectively. Similarly, VSWR and impedance are obtained as 2.22 and 29.4 - 14.62 respectively.The temperature of the sensor is varied from 40 °C to 80°Cby varying the power supply and the experiment repeated. No significant variation in these parameters is observed in the resonant frequency, return loss, VSWR and impedance of the sensor.Measurement of resonant frequency, return loss, VSWR and impedance for Microstrip patch sensor with gingelly oil at various temperatures.Cold pressed and refined gingelly oil (Idhayam brand) are used for this analysis. Initially, the temperature characteristic of cold pressed gingelly oil is analyzed by using Peltier unit mounted microstrip patch sensor. The procedure for the experiment is as followsi) Peltier unit mounted microstrip patch sensor is filled with cold pressed gingelly oil.ii) The cable and antenna analyzerare calibrated for the frequency range of I GHz to 4 GHz.iii) The oil filled microstrip patch sensor is connected with cable and antenna analyzer by using SMA connector.iv) DC power supply (0 - 30 V) is connected with Peltier unit.v) The sensing wire of the digital thermometer is inserted in to the oil under test.vi) The temperature of the Peltier unit is varied from 35°C to 105 °C by varying the DC power supply.vii) Resonant frequency, return loss, VSWR and impedance are measured from cable and antenna analyzer for Peltier unit mounted microstrip patch sensor with cold pressed gingelly oil.viii) Fix the average value of return loss as a threshold value and classify the oil as refined oil if return loss is lesser than the threshold and classify the oil as cold pressed if return loss is greater than the threshold, in the case of coconut and ground nut cooking oilsix) Similar procedure is adopted for refined gingelly oil.The measured values of resonant frequency, return loss and VSWR for the cold pressed and refined gingelly oil for different temperature are provided in tables given below.Measured values of resonant frequency, return loss and VSWR for the cold pressed and refined gingelly oil for different temperature.Table The resonant frequency and return loss for cold pressed and refined gingelly oil under different temperatures are plotted as shown in Fig.9a and Fig.9b, respectively. A constant resonant frequency of 2.38 GHz is obtained for cold pressed gingelly oil if the temperature is varied from 50 °C to 105 °C. Similarly, a fixed resonant frequency of 2.35 GHz is obtained for refined gingelly oil under similar temperature variation (Figure.9a). There is a difference in the resonant frequency between the cold pressed and refined gingelly oils. Similarly, difference in characteristics is observed in return loss, VSWR and impedance measurement for cold pressed and refined gingelly oil. A reference value of 2.37 GHz is used to classify the cold pressed and refined cooking oil under different temperatures.Interpretation from the above analysis:i) A resonant frequency of 2.38 GHz is obtained for cold pressed gingelly oil as the temperature is varied from 50°C to 105 °C. The resonant frequency of 2.35 GHz is obtained for refined gingelly oil under similar temperature variation. A difference of 0.03 GHz (30 MHz) is observed. This is found to be temperature independent in the range of 50 °C to 105 °C. A reference value of 2.37can be used to differentiate the cold pressed and refined cooking oils.ii) In the case of return loss and VSWR measurement, an increasing trend is observed for refined gingelly oil, whereas it is decreasing with temperature for cold pressed oil. A reference return loss value of - 26.5 dB is used to differentiate the cold pressed and refined cooking oils.iii) Similarly, a difference in characteristics is identified for impedance measurement. However, the variation is non-linear with temperature and hence may not be useful for classification.i) No difference in the resonant frequency is observed for the cooking oil under test with and without air bubbles.ii) A slight difference in return loss and VSWR are observed due to the presence of air bubbles in the cooking oil.This problem can be minimized by properly cleaning the microstrip patch sensor while using the different type of cooking oils and avoiding air bubbles.Advantages of the single feed mechanism of the present invention1. Microstrip patch sensor is developed as a single port device, which also acts as an antenna, which is basically a single port device, where two or more ports are not required. Hence, all the measurements are confined to single port measurement parameters. Moreover, as an antenna sensor, single port is ideal and hence the return loss and other parameters are measured for different types of cooking oils with single port.2. The microstrip patch sensor of the present invention is a low-cost device, which is fabricated from low cost acrylic material and single SMA cable and conducting sheet. The Peltier unit is fixed in one side of the device for temperature variation, and which is also a low-cost device.3. The network analyzer can be replaced by a low cost 2.4 GHz RF transceiver along with a directional coupler / circulator and a LCD display unit.Although the present invention is applicable to food industry, the present invention is not only limited to food safety and standardization authorities, but also applicable to edible oil manufacturing and refining industries, hotels and restaurants and also for general public.

Claims

We claim:

1. A device (100) tor identifying cooking oils by cuvette structured microstrip patch antenna sensor which measures the liquid quality by obtaining the resonant frequency and return loss, comprising:a SMA connector / cable(10),a network analyser (20), a high frequency cable (30) connected to the single port of said network analyser (20), a calibrating kit(40) to calibrate said network analyser (20) and a cuvette structured microstrip patch antenna sensor (50);wherein, said cuvette structured microstrip patch antenna sensor (50) which comprises of:a top substrate (I) which is formed of radiating copper patch;a bottom copper substrate (3) which is grounded; anda cavity(2) which is provided between top and bottom substrates to fill theliquid under test;wherein, said edible cooking oils under test are filled between radiating patch plane and ground plane of the microstrip patch antenna sensor, which also acts as a dielectric material, whereby no separate testing jar / container is required;wherein, said SMA connector / cable (10) is soldered through 20 mm length cable;wherein, said network analyser (20) with display is connected with said cuvette structured microstrip patch antenna sensor (50) through said SMA connector / cable (10);a Peltier unit (60) or a thermoelectric cooling (TEC) module which is fixed on ground side of the said cuvette structured microstrip patch antenna sensor (50) for temperature variation, wherein by applying the DC power source to said Peltier unit (60), heat is transferred from one side of the module to the other, whereby the effect of temperature on the oil quality measurement by said microstrip patch sensor (50) is analysed;a digital thermometer (70) and a power supply (80) provided for the temperature analysis, wherein, a sensing terminal of the digital thermometer is inserted into the cavity (2) of said microstrip patch sensor (50);wherein, the return loss of-8.76 dB for refined coconut oil and -8.3 dB for cold pressed coconut oil are obtained at 2.27 and 2.25 GHz respectively, and the return loss of-9.05 dB and -8.44 dB is obtained at 2.275 GHz for refined and cold pressed groundnut oil respectively, and the return loss of-8.42 dB and -8.7 dB for refined and cold pressed gingelly oil are obtained at 2.27 GHz respectively; andwherein, the VSWR is calculated as 2.24, 2.05 and 2.27 for refined coconut oil, refined groundnut oil, and refined gingelly oil respectively and the VSWR is calculated as 2.29, 2.25 and 2.14 for cold pressed coconut oil, cold pressed groundnut oil and cold pressed gingelly oil respectively.. The device (100) for identifying cooking oils by cuvette structured microstrip patch antenna sensor which measures the liquid quality by obtaining the resonant frequency and return loss, as claimed in claim 1, wherein, said cuvette structured microstrip patch antenna (5) is designed at 2.4 GHz and said top and bottom substrates of said structured microstrip patch antenna (50) are made of acrylic materials.

3. The device (100) for identifying cooking oils by cuvette structured microstrip patch antenna sensor which measures the liquid quality by obtaining the resonant frequency and return loss, as claimed in claim 1. wherein, said cuvette structured microstrip patch antenna sensor device provides a dual property of both sensor and antenna, where the antenna is used for transmission and reception of electromagnetic waves at 2.4 GHz.

4. The device (100) for identifying cooking oils by cuvette structured microstrip patch antenna sensor which measures the liquid quality by obtaining the resonant frequency and return loss, as claimed in claim 1, wherein, the dielectric constants of substrates made of acrylic materials (1,3) and air gap (2) are 3.7 and 1 respectively.

5. The device (100) for identifying cooking oils by cuvette structured microstrip patch antenna sensor, as claimed in claim 1, wherein said top and bottom substrates (1,3) or layers are provided with a spacing of 2.5 mm therebetween.

6. The device (100) for identifying cooking oils by cuvette structured microstrip patch antenna sensor, as claimed in claim 1, wherein the patch width and length of microstrip patch antenna sensor (50) are 48mm and 40 mm respectively, the length and width of the feed line are 20mm and 4mm respectively, and the inset feed is used for feeding technique.

7. The device (100) for identifying cooking oils by cuvette structured microstrip patch antenna sensor, as claimed in claim 1, wherein the acrylic materials used for the substrates provides low dielectric constant which varies from 1.9 to 3.7, which provides higher gain and directivity.

8. The device (100) for identifying cooking oils by cuvette structured microstrip patch antenna sensor, as claimed in claim 1, wherein, the conductor used in patch antennas is made up of two copper foils having thickness of 0.035 mm.

9. A method (200) for identifying cooking oils by cuvette structured microstrip patch antenna sensor which measures the liquid quality by obtaining the resonant frequency and return loss, comprising the steps of:providing the device having a cable and antenna analyzer, a high frequency cable, calibrating kit and the patch sensor;providing a cuvette structured microstrip patch antenna sensor which comprises of: forming a top substrate which is formed of radiating copper patch; forming of a bottom copper substrate which is grounded; and forming a cavity which is provided between top and bottom substrates made of acrylic materials to fill the liquid under test;connecting a high frequency cable to the single port of the network analyser, providing power supply to a Peltier unit and calibrating said network analyser for the frequency range of I GHz to 4 GHz before measurement;connecting said patch antenna sensorwith the network analyzer by using SMA connector and inserting a sensing terminal of the digital thermometer into the microstrip patch sensor cavity;filling the edible cooking oils / liquid under test in the cavity between radiating patch plane and ground plane of the microstrip patch antenna sensor, which acts as a dielectric material, whereby no separate testing jar / container is required;measuringSn, return loss for the microstrip patch sensor without liquid at 2.4 GHz and measuring return loss for the microstrip patch sensor with oil under test;fixing the average value of return loss as a threshold value and classify the oil as refined oil if return loss is lesser than the threshold and classify the oil as cold pressed if return loss is greater than the threshold, in the case of coconut and ground nut cooking oils; andclassify the oil as refined oil if return loss is above the threshold conditions and classify the oil as cold pressed oil if return loss is below threshold value, in case of gingelly oil.

10. The method (200) for identifying cooking oils by cuvette structured microstrip patch antenna sensor, as claimed in claim 9, wherein, said threshold values are fixed as -8.53 dB, -8.745 dB and -8.56 dB for coconut, ground nut and gingelly oils, respectively.