SYSTEM FOR DETECTION OF TOXIC SUBSTANCES IN LIQUIDS BASED ON A RING RESONATOR OPERATING AT MICROWAVE FREQUENCIES (PODES)

Technical Field of the Invention

The present invention relates to the spectral transmission properties of toxic substances mixed with water or/and other potable liquids at microwave frequencies (preferably 1 GHz-5GHz) of electromagnetic wave, by measuring them with resonance frequency technique in a ring resonator system.

Prior Art

The safety of water, subject to acute poisoning and management guidelines [1 ], is a major concern for many countries. Due to the increase in cases of water-borne poisoning every year, a number of instructions have been created on what to do immediately [2], In order to manage drinking water quality, the World Health Organization (WHO) issued the “Guidelines for Drinking-Water Quality Recommendations” in 2008. It aims to protect public health and to ensure that water is safe, sufficient, easily accessible and its supply is open to everyone. Diseases related to the contamination of drinking water pose a great risk on human health. Interventions to improve the quality of drinking water make significant contributions to human health. Those at the greatest risk of waterborne diseases are infants, children, people with weakened immune systems or people living in unhealthy conditions. The method described in the document [3], which is in the prior art, aims to eliminate the risks of disease [3],

Water resources have been one of the targets of terrorist attacks in every period of history. The aim of such attacks may be to mix a chemical or biological agent into local water resources or to damage pipelines, dams, treatment plants by placing explosives [4,5], Sodium cyanide is one of the substances that cannot be detected visually when mixed with water for this purpose.

A study on the metabolism of rats and monkeys given non-lethal doses of cyanide examines the effects of NaCN (Sodium cyanide) on the optic nervous system. The animals getting little by little doses of NaCN were observed for changes in their brains and nervous systems and for how long it takes for them to die [6],

Another study on cyanide examines the detection of cyanide ions by NMR (Nuclear magnetic resonance) spectroscopy method. The said study focuses on both the sensitive detection of cyanide and the removal of cyanide from water. However, in the method studied, the detection is made by a sensor contacting the water [7],

In addition to poisons which can be mixed with liquids, in another study aiming to measure water quality, heavy metals in water are detected by a split-ring resonator in the frequency range of 1 GHz to 10 GHz [8], As in the said study, "detection with a resonator" has come to the fore in microwave frequency band, albeit for different purposes.

Studies using a ring resonator includes such applications as gasoline quality testing by a planar ring resonator, dielectric coefficient calculation in water, ethanol and methanol by a split-ring resonator [9] and sensitive measurement of trace amount water-dissolved sodium [10],

In another study, a ring resonator sensor operating at a frequency in the range of 1 GHz to 1.2 GHz connected to a microstrip line is used for concentration measurements of aqueous phosphate, nitrate and mixed phosphate [11 ],

In [12] the component concentrations in the liquid mixture are measured with a specially designed split-ring resonator operating at 150 MHz.

A planar microwave sensor [13], based on metamaterial technology and split-ring resonator, was utilized for blood glucose measurements in the contactless system operating at 1 -6 GHz band with Vector Network Analyzer (VNA).

In parallel with the system for toxic substance detection in water, described in the T urkish patent application numbered TR2020/08906, a different detection device has been developed in the present invention. The detection method described in the present invention is completely different. That is why, the operation frequency ranges are also different. The present invention utilizes lower frequency ranges. There are also differences between detection doses. The present invention includes a study to determine whether there is a toxic substance mixed into potable liquids by a ring resonator at microwave frequency. If there is a toxic (dangerous) chemical in the water, it should be prevented from drinking and sent for detailed testing. Special ring resonators should be designed for certain liquid groups.

The present invention describes a method that can be used anywhere and is easy to use outdoors, with such advantages as conducting measurements remotely without contacting a sample in a container, not damaging the sensor because there is no liquid exposure, not emitting ionized rays, taking instant measurements. The device realizing the proposed method is light and portable.

Technical Problem that the Invention Aims to Solve

The present invention is aimed to detect industrial or toxic substances mixed into drinking water, underground spring waters or potable liquids for various reasons. Another purposes of the present invention is 1 ) to classify the drinking water presented to high-ranking state officials during meetings as "Toxic (Dangerous) or Non-Toxic (Safe)" by detecting the spectral shifts on the basis of differentiation algorithms through the invented system to be placed under meeting tables, 2) to make instant detection of toxic substances at lethal or non-lethal doses that could be mixed into the drinking waters of administrators at critical positions. The system works in real time. It is lightweight and portable. It conducts detection of liquids in containers without contacting the liquids. Since it does not emit ionizing rays, it does not harm the users and people around it. The device is supplied with user-friendly interface. The device in the present invention will be described in more detail and specifically through the toxic substances in Table 2. The detection abilities of our device are not limited only by the measured liquids mention in Table 2. The interpretation of the claims cannot be limited by the scope of the examples of the claimed invention contained in the description

The present invention proposes the use of a ring resonator measuring device. The ring resonator, designed specifically for the present invention, offers the capability to detect liquids in glass or plastic containers without contacting the liquid. Electromagnetic differences in the compositions of chemical substances were examined by placing them into the ring resonator of toxic liquid detection device. In the light of the information obtained from the examinations, with the differentiation algorithms, water or drinkable liquids are grouped either as "Toxic (Dangerous)" or as "Non-Toxic (Safe)" based on whether toxic substances are mixed into them or not. "Toxic" or "non-toxic" liquids are distinguished through a list of previously measured liquids in a database by the difference between the measurement results of its natural state and the measurement results with added poison. Therefore, sufficiently large data libraries are created.

In the present invention, a designed ring resonator operates in a range from 1 GHz to 5 GHz, that involves 3 (three) separate resonance frequencies. The behavior of liquids in these three different modes has been examined. It has been assumed that each chemical would have separate distinguishing features at these resonance frequencies. The usage of data obtained for all three resonant frequencies guarantees the more robust detection. In our invention, the ring resonator is boxed with a VNA card, which is a commercial product allowing a portable usage. The device in the invention is capable of real-time operation. Data transfer and power supply of the card are done with a laptop computer. Grouping studies are carried out using the commercial software MATLAB (Matrix Laboratory) and JMP (Statistical Software) [14], With the measurements, using the difference of resonance shifts between pure water and toxic- added/mixed water, it is determined non-invasively whether there is a toxic substance mixed with the water, or not. "Toxic" chemicals are indicated as "dangerous" in graphs.

Descriptions of the Figures

Figure 1 : Schematic drawing of the ring resonator

Figure 2: Schematic drawing of the toxic liquid detection device with a ring resonator

Figure 3: Comparison graph of the measurements of pure water/cyanide water in a glass beaker (1 ,8GHz to 5.5GHz, in 3 modes)

Figure 4: Comparison graph of the measurements of pure water/cyanide water in a glass beaker (1 ,8GHz to 3GHz, in single mode)

Figure 5: Comparison of the measurement graphs of materials named b, d, e, f in Table 2 and air (a) in a glass bottle (1 .8 GHz to 5.5 GHz). Figure 6: Comparison of the measurement graphs of materials named b, d, e, f in Table 1 and air (a) in a glass bottle (1 .8 GHz to 3 GHz)

Figure 7: Comparison of the measurement graphs of materials named b, d, e, f in Table 2 and air (a) in a plastic water container (1 .8 GHz to 5.5 GHz)

Figure 8: Comparison of the measurement graphs of materials named b, d, e, f in Table 2 and air (a) in a plastic water container (4.6 GHz to 5 GHz)

Figure 9: Demonstration with JMP software that the liquids named d, e, f, in Table 2 are differentiated from the liquid named b (water)

Figure 10: Schematic representation of the prototype device with a glass bottle

Descriptions of theReferences in the Figures

1 : Inner and outer diameters of the Ring Resonator

2: Transmission line width and length

3: RF (radio frequency) cable connecting the VNA card (5) and the ring resonator (1 )

4: Outer box

5: VNA card

6: USB cable for Data transfer and power feed

7: Duroid substrate of the ring resonator

8: Plastic water container (Measuring container)

9: Rectangular bottom plastic water container with a base size of 58mm x 58mm

10: Rectangular bottom plastic water container with a height of 74mm

11 : Drawing of 150ml glass lab flask

12: 150ml glass lab flask with a height of 150mm

13: 150ml glass lab flask with a bottom diameter of 54mm 14: Computer/ Laptop

15: Interface and Grouping algorithm

16: Glass beaker (100ml)

17: Glass beaker with a height of 80mm

18: Glass beaker with a diameter of 60mm

X: Connection points of RF cable from VNA card (5) with ring resonator

A: Space between transmission line and ring

R1 : Inner diameter of the ring resonator

R2: Outer diameter of the resonator

The dimensions of the containers (glass bottle, plastic water container, etc.) are given for reference to the results in the graphs below. The device produces different results for each type of the containers used. The device proposed is capable also successfully operate with bottles of different shape and sizes.

Description of the Invention

The present invention includes a study to determine whether there is a toxic substance mixed into potable liquids or water by a ring resonator at microwave frequency. And it prevents drinking a liquid in case of a Toxic (Dangerous) chemical in the liquid and suggests sending it to the detailed testing.

The proposed device comprises of VNA card (5), ring resonator (1 ), 2 RF Cables (3), computer (laptop or desktop) (14), USB cable for Data transfer and power feed (6), VNA data transmission software and interface (15) and outer box (4).

The computer (14) can preferably be a laptop or desktop. Instead of the computer (14), a device that functions like a computer can also be used.

The outer box (4) can preferably be metal or plastic.

The RF cable with VNA output (3) connects the VNA card (5) to the ring resonator (1 ). The VNA Card (5) in the present invention, operates in a frequency range of 300 kHz to 6 GHz. The measurement speed of each frequency step is 182 ps (microseconds) at 118 dB (decibels) dynamic range, 10Hz IF (Intermediate Frequency) bandwidth. The VNA Card allows conducting 2 ports measurements of the S parameters (Sn, S12, S21, and S22), and is controlled by the computer (14) through USB

The VNA data transfer software and interface is based on the Visual C program. This interface allows real time data transfer. The interface also allows monitoring and recording the amplitude (in logarithmic scale) and phase data. Amplitude and phase data on a logarithmic scale can be viewed and recorded on the interface.

Ring resonators are used to characterize materials in microwave frequency ranges and to determine their dielectric properties. The device can include the following microwave components as coupler, RF filter, mixer, oscillator, and antenna. The system in the present invention describes the relationship between resonance and frequency. The proposed system measures the characteristics of the resonance occurring in the ring resonator loaded with the vessel containing the liquid under study. A ring resonator is composed of a ring placed on a substrate and a transmission path. The characteristic impedance chosen is 50 ohms. The ring resonator is schematically shown in Figure 1 .

There is a small space gap between the transmission line and ring resonator (denoted by Delta (A) in Fig. 1 ). This gap controls coupling between the resonator and transmission line. The width of the transmission line varies between 0.1 and 1.0 times of gap. The ring resonator is designed on a duroid base with a dielectric constant of 2.33 [18],

Resonance condition for the ring resonator can be approximated by the following formula:

2 R = n _g , n = 1,2,3, ■■■ (I) where R is the ring radius, “n” is the resonance harmonic number, and g is group wavelength defined as here c is speed of light in vacuum, f is a resonance frequency, and E _eff is dielectric constant [19, 20, 21 ],

The ring resonator operating at different harmonics between 1 GHz and 5 GHz is manufactured on a duroid substrate (7) whose dielectric constant is 2.33 [18], The ring resonator was designed in CST (Computer Simulation Technology) Studio Suite 3D EM [20] software. The resonance frequency of the unloaded Ring Resonator (without liquid) is shown in Figure 3. The resonator dimensions are presented in Table 1 .

Table 2 describes the liquids examined within the scope of the invention. This information is available at the web site of "Toxnet Toxnet is the toxicology data network of the National Library of Medicine of the United States of America. It provides access to databases on toxicology, hazardous chemicals, environmental health and toxic releases.

Table 1. Specifications of the Ring Resonator.

In the present invention, the VNA card (5) is placed in the metal box (4). The RF cable outlets (3) are connected to the ring resonator (1 ) through points (x) as shown in Figure 10, and the ring resonator (1 ) is located on the droid substrate (7). The ring resonator (1 ), the RF cable (3) and the droid substrate (7) containing the transmission lines are positioned on the metal box (4). The data transfer and feeding cable (6) coming out of the metal box (4) is connected to the laptop computer (14) through the USB output. Connections are driven by the interface (15) software. Voltage amplitude measurements on a logarithmic scale are made in the resonator unloaded (filled with air) and loaded with water and potable liquid. In this way, a reference data library for known liquids is also created. For the tests the following toxic substances, available in the, were selected. The list of liquids used for detection is in Table 2.

Table 2. Liquids examined within the scope of the invention.

Measurements were conducted while putting the measurement container (8), glass beaker (16) or glass bottle (11 ) in the central part of the ring resonator. The resonance behaviors, differing from water, were distinguished both by graphics (Figures 3, 4, 5, 6, 7, 8) and by grouping algorithms (Figure 9). Then on this basis the liquids were recognized as “Toxic (Dangerous)” or “Non-Toxic (Safe)”.

The measurements employed 150 ml glass beakers (16, 17, 18) with a height of 80 mm and a base diameter of 60 mm, 500 ml lab flasks with a base diameter of 62 mm and plastic water containers with a rectangular bottom of 55mm x 58mm (8, 9, 10).

The liquids given in Table 2 (except cyanide) were first prepared and measured in a glass bottle (11 ). Then, these liquids were transferred into plastic containers (8) and measured. Thus we got the results for the liquids in the different types of vessel First, in the glass beaker, only pure water was examined, and then the mixture of water and cyanide was studied. Conclusion:

The expected result of the study is to determine whether the results of a chemical- added water or potable liquid differ from the results of water or other potable liquids registered in a data library. The detection is based on the comparison whether the spectral characteristics obtained for unknown liquid differ from the known spectral data for water or other potable liquids registered in a reference data library.

It should be pointed out that the reference spectral data for the liquids placed in vessels of different types, shapes, and sizes should be available in the data library. For this reason, it is highly desirable to create a spectral database for liquids and vessels available in the market as wide as possible.

Figure 3 and 4 show the comparison of the measurement results for the pure water and the mixture of sodium cyanide and pure water, which is detailed in Table 1. For a more detailed observation, the 1 GHz to 3 GHz range was re-examined in Figure 4. Noticeable that the spectral shifts in the Figure are quite evident. Figure 3 examines the response of sodium cyanide for three different resonance modes and attracts attention to the shifts in the range of 1.8 GHz to 3 GHz, where the shifts are best observed. It is seen that both amplitude and frequency are different from water. The liquids to be measured were prepared by using a glass beaker (8).

Figures 5, 6, 7, and 8 show the graphs for the liquids denoted d, e, f in Table 1. The graphs differ from the liquid named b (Water) in the glass bottle (11 ) and in plastic water container (8). First the behavior at three resonance frequencies is demonstrated, then in the mode in which the best resonance shift occurs.

The glass bottle was examined in the 1 .3 GHz - 3 GHz range, while the plastic water container was examined in the 4 GHz - 5.4 GHz range. All three toxic chemicals differed from water. Their spectrum lines have lower values and they are closer to each other.

Industrial Applicability of the Invention

Potential usage areas of the present invention are municipalities, hotels, crowded public buildings, and entourage of government officials requiring high level protection where potable liquids or waters need to be checked. Its practicality and portability make it quite easy utilize almost anywhere. REFERENCES

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