Technical Field

The invention relates to non-invasive ultrasound sensors in the structure of the Mach-Zehnder Interferometer for determining the proportion of methyl alcohol (methanol) that mixed/was mixed in the ethyl alcohol (ethanol), which causes serious health problems when inhaled or digested, because of its toxicity.

Prior Art

Ultrasound sensors in the prior art are used in many areas such as distance detection, liquid/gas flow rate measurement, liquid level measurement, detecting structural cracks and parking assistance systems. However, the use of the mentioned sensors in detecting liquid and gas density (concentration) is very limited.

In the prior art, to determine the methyl alcohol in ethyl alcohol, the method of oxidation of the alcohol mixture to aldehydes and colour tests because of oxidation is used. In the mentioned method, the detection process is carried out by chemical reaction. In addition, the waiting time requirement and colour perception differ from person to person.

Another method in the prior art is gas chromatography, which is used to distinguish methyl alcohol from ethyl alcohol. Generally, the method is based on the principle of separating heat-resistant compounds, which can become volatile without degradation, by moving in a column at different speeds. Although qualitative and quantitative analyses can be performed with the method mentioned, tests can only be performed in a laboratory environment. Another method used in the prior art to determine the presence of methyl alcohol is based on the refraction of light, which is a physical characteristic. In the mentioned method, the proportion of methyl alcohol in ethyl alcohol can be determined from the values measured with an immersion refractometer.

Another method used in the prior art to detect methyl alcohol in ethyl alcohol is Raman spectroscopy. Methyl alcohol is determined by using the chemical properties of molecular structures with Raman spectroscopy. With shifts in the Raman spectrum, mixing proportions between methyl alcohol and other alcohols can be determined. In the mentioned method, measurements are made in a laboratory environment.

Another method in the prior art is the concentration method based on mechanical oscillations and density measurement via mass flow. In the mentioned method, specifically density data is required. In addition, high vibration sensitivity and high cost are among the disadvantages of this method. In addition, the method of concentration determination based on conductivity measurement and pH value can only be applied to certain liquids and its measurement capability is quite limited.

Ultrasound liquid sensors are also among the methods used to detect concentration in liquid mixtures. Detectors based on defects in phononic crystals have been developed to detect the ethanol proportion in a mixture with water. In addition, the acoustic sensors in the Mach-Zehnder interferometer structure have been theoretically shown before. Theoretically shown sensors work by the acoustic waves, which are separated into two identical branches, interfere with the formation of phase difference after passing through different environments. In the Mach- Zehnder interferometer created with a T-branched waveguide into a steel medium, a region in the sample arm was filled with the analysed liquid mixture (analyte). The liquid concentration mixed into the water can be determined by the slides at the transmission peak frequency resulting from the phase (transmission time) differences between the wave transmitted along the sample arm where the analyte is located, and the wave transmitted along the reference arm. However, filling only the desired area with analyte is not a practical application. The major disadvantage of the said self-onentation-based sensor design method is that it requires a partition separated by a thin membrane to place the sample.

In the international patent document coded W003000119A2 in the prior art, characterization of fluids by ultrasound method is mentioned. The method stated in the mentioned document aims to determine the physical properties of liquids, especially food solutions, by ultrasound reflection. The physical characterization of the fluid of interest is performed via these stages: Longitudinal ultrasound wave generation, matching the transducer with the examined fluid, sensing the reflected longitudinal waves, and correlating the physical properties of the measured with the specific properties of the reflected ultrasound waves.

The gas concentration sensor is mentioned in the European patent document EPl 361430 in the prior art. The document mentions detection of gas instead of liquid. The concentration of a particular gas in the gas mixture to be measured is determined based on the time between the transmission of the acoustic wave and the recovery of the reflected acoustic wave.

The method of detecting methyl alcohol in alcoholic beverages is mentioned in the national patent document TR200501987 in the prior art. In the mentioned method, viscosity device, chronometer and calibration information are used to determine whether the alcoholic beverage contains methyl alcohol, which is the toxic chemical. The test method is based on revealing the identity of the chemical based on the difference in viscosity of the fluids. Based on the time the solution spends in the viscosity device and the calibration information, the methyl alcohol content in the solution is determined.

The acoustic signal detector is mentioned in the national patent document coded TR201104114 in the prior art. Said detector is used to detect a target moving in water. The acoustic signal detector may include the body with a front portion, wherein the front portion has a tapering cross-section and an end shaped to be a plane. The plane may be perpendicular to a direction of movement of the acoustic signal detector. The acoustic signal detector may also include several arrays of sensors configured to generate sound and to detect sound reflected by a target.

Purpose of the Invention

The purpose of the invention is to provide the ability to measure the concentration of paired liquid mixtures in beverages, pharmaceutical chemicals, and other related industries.

Another purpose of the invention is to ensure the determination of the proportion of methyl alcohol (methanol) that mixed /was mixed with ethyl alcohol (ethanol), which causes serious health problems when inhaled or digested, because of its toxicity, with a high precision.

Another purpose of the invention is to achieve a portable ultrasound concentration sensor.

Another purpose of the invention is to achieve an ultrasound concentration sensor that can be used repeatedly.

Another purpose of the invention is to achieve an ultrasound concentration sensor that does not require warm-up time and can produce results as soon as the sample is loaded.

Another purpose of the invention is to achieve an ultrasound concentration sensor that enables samples to be examined sequentially without waiting.

Another purpose of the invention is to achieve an ultrasound concentration sensor that does not require sensitive components such as chemical etc.

Concentration sensor developed to achieve the mentioned purposes includes:

- a signal generator (1) that produces electrical sine signals at different frequencies, - a voltage amplifier (2) increasing the amplitude of the signal received from the signal generator (1),

- an ultrasound transducer transmitter (3 A) made of piezoelectric ceramic disc and converts electrical signals into mechanical vibrations,

- an ultrasound transducer receiver (3B), made of piezoelectric ceramic disc and converting electrical signals into mechanical vibrations,

- a Mach-Zehnder Interferometer (4), which separates ultrasound waves into two identical branches and allows them to interfere later,

- the input signal (5) consisting of acoustic vibrations that move through the waveguide at the entrance of the interferometer,

- the signal branching (6) that forms the acoustic signal components that will interfere,

- a sample cell (7 A) containing the ethanol-methanol mixture to be measured,

-a reference cell (7B) containing pure ethanol for contrast,

- an acoustic interference (8), formed by the combination of two ultrasound signals of close amplitude with phase difference and forming waves of varying amplitude depending on the function of the phase difference,

- an output signal (9) consisting of the combination of interfering waves,

- an analog to digital converter (10) that enables the conversion of analog electrical signals received from the receiver transducer into digital signals,

- the computer (11) that enables the data to be processed and the mixing proportion to be calculated,

- an input signal (12) consisting of ultrasound signal at transmission peak resonance frequency, - an output signal (13) consisting of the resultant signal created by the interfering waves at the exit,

- water (14) used as background fluid,

- a steel bar (15), one of the periodic units that make up the phononic crystal structure,

- a polyethylene tube (16) containing pure ethanol and ethanol-methanol mixture,

- an input / output waveguide (17) that enables the acoustic wave to be directed to the branches at the entrance of the interferometer and to the receiver transducer at its exit,

- a T branching (signal branching) (18) that separates the signal into two identical components at the entrance, creates interference at the output and directs it to the output waveguide,

- a 90° twist (19), which changes the direction of the waves moving in the acoustic waveguide by 90 degrees,

- a tubes sample cell (20), in which the mixture proportion of ethanol-methanol is to be determined,

- a reference cell (21) consisting of sample cells containing pure ethanol and the same number of tubes,

- phononic crystalline bulk building bands (22) consisting of phononic crystalline dispersion bands that do not contain any defects,

- acoustic band spacing (23) consisting of the frequency range of acoustic waves that cannot be transmitted through the phononic crystal, - linear waveguide transmission band (24), which consists of the scatter graph of the waves that can move by being confined in the waveguide structure in the phononic crystal,

- a resonance peak (25) of about 200 kHz measured at the exit of the interferometer for pure ethanol sample.

Description of Figures

The attached Figure - 1 is the block diagram of the product subject to the invention.

Figure-2 is the schematic view of the ultrasound Mach-Zehnder interferometer.

Figure-3 is the band structure of the phononic crystal waveguide for pure ethanol.

Figure-4 is a graph of the displacement of the conduction peak of the Mach-Zehnder interferometer with the methanol proportion.

The main elements expressed in the description, claims and / or figures are given below as numbers and names.

(1) Signal generator

(2) Voltage amplifier

(3 A) Ultrasound transducer transmitter

(3B) Ultrasound transducer receiver

(4) Mach-Zehnder Interferometer

(5) Input signal

(6) Signal branching (7 A) Sample cell

(7B) Reference cell

(8) Acoustic interference

(9) Output signal (10) Analog to Digital converter

(11) Computer

(12) Input signal

(13) Output signal

(14) Liquid (Water) (15) Steel bar

(16) Polyethylene tube

(17) Input / Output waveguide

(18) T branching

(19) 90° Twist (20) Sample cell

(21) Reference cell

(22) Phononic crystalline bulk building bands

(23) Acoustic Band Spacing

(24) Linear Waveguide Transmission Band (25) Resonance Peak

Explanation of the Invention

The invention relates to non-invasive ultrasound sensors in the structure of the Mach-Zehnder Interferometer for determining the proportion of methyl alcohol (methanol), which mixed / was mixed with ethyl alcohol (ethanol) and causes serious health problems when inhaled or digested, because of its toxicity.

The product of the invention has a Mach-Zehnder interferometer architecture, where it can be used to determine the mixing proportions in a wide range of paired liquid mixtures as shown in the example of ethyl alcohol - methyl alcohol mixture.

The portability of the product subject to the invention is one of its most important advantages and it also has the feature of being reusable since it does not contain moving parts or consumables that need to be changed between measurements. In addition, the product does not require warm-up time and can get results as soon as the sample is loaded. Another critical performance criterion in liquid and gas sensors is the recovery time and the recovery time of the device subject to the invention is zero. In other words, samples can be examined successively with the device without waiting. In addition, the product is label-free, that does not require sensitive components such as chemicals etc. for detection.

An important problem with ultrasound concentration sensors is that the speed of sound changes with ambient parameters such as temperature, pressure and humidity, and the calibration curves of the devices shift. Since the product subject to the invention has an interferometric structure, the acoustic waves separated into two branches are affected in the same way by the change of ambient parameters. Thus, the effects caused by the sound speed change are eliminated. Also, since there is water in the background, the internal temperature of the device can be controlled by means of a thermostat. The product is long-lasting and durable due to its structure, and its life depends on the lifetime of the electronic circuits and piezoelectric transducers used, rather than the sensor components. The product can be controlled remotely and does not need to be connected to other devices to operate. In addition, the product is compact and can be miniaturized by changing the operating frequency.

Ultrasound sensors work based on the frequency shift in the interference signal, which shows methanol and ethanol based on sound speed and intensity differences. Said ultrasound sensor allows detection of methanol in ethanol with 1% precision.

Ultrasound liquid concentration sensors aim to determine the mixing proportion in a homogeneous paired liquid by measuring the speed of sound in the liquid. In order to achieve the aforementioned purpose, the arrival time of the ultrasound signal sent from a transmitter (transducer) to the receiver is measured; by knowing the path taken, the speed of sound in the liquid can be determined. The mixing proportion is determined by comparing the varying sound speeds depending on the concentration of the mixture with the current sound speeds. As a result, the concentration measurement of paired liquid mixtures in beverages, pharmaceutical chemicals and related industry can be made with the ultrasound sensors of the invention. For example, it can be used to determine secondary foreign liquids in water, in milk and other liquid food analyses and to measure the purity of fuel.

The method of determining the concentration of the sensor subject to the invention is based on the detection of the frequency shift of a narrow transmission peak corresponding to a physical resonance in the ultrasound system. The reason for the shift in the transmission peak arises from the sound speed and density changes of the mixed fluids, as mentioned in the above methods. Interferometric sensors are very useful for precise concentration measurements. Phase shifts based on the effective path difference between the branches of the interferometer are useful in detecting the concentration proportions within the structure. Phononic crystal based interferometric sensors can be used in physical, chemical, or biological sensing applications. Non-invasive ultrasound sensor subject to the invention includes:

- a signal generator (1) that produces electrical sine signals at different frequencies,

- a voltage amplifier (2) increasing the amplitude of the signal received from the signal generator (1),

- an ultrasound transducer transmitter (3 A) made of piezoelectric ceramic disc and converts electrical signals into mechanical vibrations,

- an ultrasound transducer receiver (3B), made of piezoelectric ceramic disc and converting electrical signals into mechanical vibrations,

- a Mach-Zehnder Interferometer (4), which separates ultrasound waves into two identical branches and allows them to interfere later,

- the input signal (5) consisting of acoustic vibrations that move through the waveguide at the entrance of the interferometer,

- the signal branching (6) that forms the acoustic signal components that will interfere,

- a sample cell (7 A) containing the ethanol-methanol mixture to be measured,

-a reference cell (7B) containing pure ethanol for contrast,

- an acoustic interference (8), formed by the combination of two ultrasound signals of close amplitude with phase difference and forming waves of varying amplitude depending on the function of the phase difference,

- an output signal (9) consisting of the combination of interfering waves,

- an analog to digital converter (10) that enables the conversion of analog electrical signals received from the receiver transducer into digital signals, - the computer (11) that enables the data to be processed and the mixing proportion to be calculated,

- an input signal (12) consisting of ultrasound signal at transmission peak resonance frequency,

- an output signal (13) consisting of the resultant signal created by the interfering waves at the exit,

- water (14) used as background fluid,

- a steel bar (15), one of the periodic units that make up the phononic crystal structure,

- a polyethylene tube (16) containing pure ethanol and ethanol-methanol mixture,

- an input / output waveguide (17) that enables the acoustic wave to be directed to the branches at the entrance of the interferometer and to the receiver transducer at its exit,

- a T branching (signal branching) that separates the signal into two identical components at the entrance, creates interference at the output and directs it to the output waveguide (18),

- a 90° twist (19), which changes the direction of the waves moving in the acoustic waveguide by 90 degrees,

- a tubes sample cell (20), in which the mixture proportion of ethanol-methanol is to be determined,

- a reference cell (21) consisting of sample cells containing pure ethanol and the same number of tubes,

- phononic crystalline bulk building bands (22) consisting of phononic crystalline dispersion bands that do not contain any defects, - acoustic band spacing (23) consisting of the frequency range of acoustic waves that cannot be transmitted through the phononic crystal,

- linear waveguide transmission band (24), which consists of the scatter graph of the waves that can move by being confined in the waveguide structure in the phononic crystal,

- a resonance peak (25) of about 200 kHz measured at the exit of the interferometer for pure ethanol sample.

Phononic crystal waveguide (input / output waveguide) (17): Linear input / output waveguides (17) are used in directing ultrasound waves with little loss in phononic crystals, which are periodic elastic structures. In the product subject to invention, the input / output waveguide (17) is designed as a polyethylene tube (16) containing pure ethanol or ethanol -methanol mixture in the phononic crystal consisting of steel bars (15). As the size of the phononic crystals gets smaller, their operating frequency increases, sensitive detection is possible in liquid mixtures in volumes of microliter with the developed product. Since the product is a liquid sensor, the mixture whose concentration will be determined is attached to polyethylene tube (16) with syringes, pumps, etc. and the sample chamber can be washed with pure ethanol between two measurements.

A critical technical feature in the design of the input / output waveguide (17) is the acoustic impedance matching of the polyethylene tube (16) material with the liquids (14) inside the tube (ethanol or ethanol-methanol mixture) and outside (water). Polyethylene is a material with a Z = 2.93x106 kg/m ² .s acoustic impedance close to that of water (Z = 1.48x106 kg/m ² .s), as well as being flexible, durable and can be produced in thin wall thicknesses. Therefore, the reflection of acoustic waves and thus the signal loss will be at the lowest level in liquid-solid-liquid transitions.

T branching (18) and signal branching (6): Phononic crystal waveguides make "T" branching with 90-degree twists, minimizing the losses in the direction of the directed wave, and simplifying the interferometer design. In addition, T branching (18) and signal branching (6) are critical for the separation of the ultrasound wave sent to the system, i.e. the input signal (5), into two identical branches.

Acoustic interference (8): In the Mach-Zehnder interferometer (4), the acoustic path can be designed in the desired length. This makes the acoustic interference (8) at the interferometer output caused by the phase delay in the sample cell more effective and enables the liquid mixture proportion to be determined with high precision.

Piezoelectric ultrasound transducer receiver (3B) and ultrasound transducer transmitter (3A): The piezoelectric disc-shaped ultrasound transducer transmitter (3 A)- ultrasound transducer receiver (3B) pair used in the product subject to the invention allows high precision measurement of liquid mixture proportions by matching the resonance frequencies with the waveguide transmission band (24). In addition, by stimulating the interferometer with Gaussian pulses, the measurement precision can be further increased by averaging many measurements in a short time.

The interferometric liquid sensor works as follows: The input signal (5) generated by the signal generator (1) is amplified by the radio frequency voltage amplifier (2) and transmitted to the ultrasound transducer transmitter (3A), which acts as a loudspeaker. (Figure-1) Ultrasound sound waves emitted from the transducer reach the Mach-Zehnder interferometer (4), which consists of steel bars (15) and polyethylene tube (16). (Figure-1) The input signal (wave) (5) moving from the input waveguide is separated into two with equal intensity and each move along the sample arm and the reference arm by changing its direction twice by means of 90° twists (19). (Figure-1) Waves gaining phase difference by passing through the sample cells (7A, 20) and reference cells (7B, 21) in the arms are exposed to acoustic interference (8) in the output signal (13), that is in the waveguide, and the ultrasound transducer receiver (3B) is transmitted. The output signal (9) amplified by the amplifier is transferred to the computer (11) by the analog to digital converter (10). The input signal sent from the entrance (5) moves along the Mach-Zehnder interferometer (4) at a certain frequency called the resonance peak (25) (Figure-4), that is the acoustic interference (8) of the waves coming from the sample cell (7 A) and reference cells (7B), the resulting resultant wave intensity, ie the output signal (9), can be measured at the output by means of the ultrasound transducer receiver(3B). (Figure 1).

Cylindrical stainless-steel bars (15) prepared by laser cutting and CNC lathe and polyethylene tube (16) were mounted between deep support plates in Mach- Zehnder interferometer (4) architecture. (Figure-4) Pure ethyl alcohol input/ output waveguides (17), T branches (18) and methyl / ethyl alcohol mixture in the reference cell (21) are also injected into the tubes in the sample cell (20). Here, it is aimed to act like an input / output waveguide (17) that transmits the input signal of the fluids injected into it with the tube, without dispersion.

With the change in the methanol proportion of the sample cell (7 A) in the sample arm, the resonance frequency (peak) (25) shifts significantly (Figure-4). By comparing the increasing methanol ratio and the shift to low frequencies (red) with numerically calculated values, the ratio of methanol mixed / was mixed in ethanol can be determined. The peak frequency (resonance peak) (25) was chosen as the peak value of the closest transmission peak of 200 kHz, which is the resonance frequency of the piezoelectric ultrasound transducer receiver (3B) and the ultrasound transducer transmitter (3 A) (Figure-4).

Table 1- (a) Peak frequency shift and (b) constant frequency acoustic intensity with methanol proportion.

The resonance peak (25) frequency shifts linearly to lower values as the proportion of methanol in ethanol increases (Table-la). Linear variation in the range of 0% - 20% enables the product to determine methanol in ethanol with high precision. The shear rate per unit change in metal ratio is Af = -8.7 Hz /%. Since the width of the resonance peak is about 20 Hz and the quality factor of the peak Q = 10,000 (Figure- 4), this change can be easily measured with standard electronic equipment. Therefore, the product subject to invention can be used to determine the methanol content in ethanol with high precision.

The methanol ratio of the peak frequency in the product and the amount of shear are determined by measuring the output amplitude at each frequency by changing the frequency of the electrical sine wave. Alternatively, a fast response time can be achieved by calculating the frequency spectrum of the output signal using a Gaussian enveloped pulse covering a sufficiently wide frequency range at one time.

Also, at a fixed frequency, the acoustic intensity decreases exponentially with increasing methanol ratio (Table- lb). This can be used to accurately determine the methanol content. In the method, room temperature (20 °C) was chosen as the operating temperature. Sound speed (c) values for pure ethanol and pure methanol are from Reference- 1 (Reference 1 : Kiyohara O. Benson GC (1979) Ultrasound Speeds and Isentropic Compressions of n-Alkanol + n-Heptane Mixtures at 298.15 K. J. Chem. Thermodyn., 11 861-873.); density ( ?) values are taken from Reference-2 (Reference-2: http://ddbonline.ddbst.de/DIPPR105DensityCalculation/DIPPR10 5CalculationCG I.exe) and these values are as follows for water, pure ethanol and pure methanol: Cwater ⁼ 1482.40 m/s, Cethanol ⁼ 1142.29 m/s, Cmethanol ⁼ 1103.00 m/s, Xvater ⁼ 998.200 kg/m ³ , /Ethanol = 783.924 kg/m ³ , mcthanoi = 786.500 kg/m ³ . In the invention, investigations were made for the mixing of methanol in ethanol up to 20% by weight, but not for higher methanol concentrations. For polyethylene tube, the density value is taken as PE = 930 kg/m ³ , Young's Modulus EPE = 1.06 GPa, and Poisson Ratio as V E = 0.40. For steel, these values are taken as stcci = 7850 kg/m ³ , Esteei = 205 GPa and Hteei = 0.28, respectively. All calculations were made using the Finite-Element Method (FEM).

In alternative embodiments of the invention, the product subject to invention can be formed by using linear input / output waveguides (17) that do not contain interferometric operation. It can also be created by exploiting point defect states interacting in the phononic crystal. Alternatively, the Mach-Zehnder interferometer can be designed with Y branching instead of T branching (18). In addition, there may be alternatives such as the types of polyethylene tubes (16) used in the system, the way they are connected to each other and loading with a peristaltic pump instead of manual.