CN218068146U - Detection device - Google Patents

Abstract

The utility model relates to a detection device integrating EIS liquid impedance measurement and refractometer, which comprises an optical measurement system, an impedance measurement system and a processing system; the optical measurement system comprises a light source system, a reflecting prism and an optical receiver system; the impedance measurement system comprises an electrode system and a circuit system; the processing system is connected with the optical receiver system and the circuit system; the testing device comprises a reflecting prism, a ring-shaped piece, an electrode system and a liquid storage tank, wherein the reflecting prism is arranged on one surface of the reflecting prism, a hollow-out part in the middle of the ring-shaped piece is matched with one surface of the reflecting prism to form the liquid storage tank for containing liquid to be tested, an electrode of the electrode system extends into the liquid storage tank to be contacted with the liquid to be tested, and the liquid to be tested in the liquid storage tank forms an interface between the surface of the prism and the liquid level on the reflecting prism so as to realize simultaneous testing of refraction and liquid impedance.

Description

Detection device

Technical Field

The utility model relates to a liquid measurement field specifically relates to a fuse EIS liquid impedance measurement and refractometer's detection device.

Background

Measurement using Electrochemical Impedance Spectroscopy (EIS) is a common method for liquid measurement. Electrochemical impedance spectroscopy, i.e., measuring the change in impedance with the frequency of a sine wave, is very effective for the detection of liquids involving ionic conduction, especially multi-ionic mixed liquids, and a considerable part of the information in mixed ionic solutions can be easily obtained by using an EIS system. The refractive index of the liquid is increased after the solid soluble substances are dissolved, and the measurement of the content of the solid soluble substances can be achieved through refractive index measurement, so that the refractometer can be used for measuring the content of the solid soluble substances in the liquid.

However, the refractometer only reflects the concentration of soluble solids in the liquid in the measurement process, and such a measurement mode has disadvantages in measuring many liquids, for example, when measuring a liquid with a low ion concentration, the refractometer cannot be very accurately evaluated, and then is a mixed solution mixed with ions, active substances, cells and the like, and the refractometer only reflects the properties of soluble parts in the liquid, but cannot reflect the properties of insoluble proteins, cells and the like. For example, when the sucrose aqueous solution is prepared by ultrapure water, the sucrose does not have other ionized ions except sucrose molecules inside the sucrose aqueous solution, and the sucrose exists in a molecular crystal state and does not have an ionized state, so that information displayed by the sucrose aqueous solution during electrical impedance measurement does not greatly differ from water, and the concentration of the sucrose aqueous solution cannot be judged by simply measuring the electrical impedance.

Therefore, both the refractometer and the EIS system have problems of being unable to measure or inaccurate in measurement, and although the accuracy can be increased by separate measurement of the refractometer and the EIS system, new problems arise, such as the risk of contamination of the sample during the transfer process, and particularly, the problem of insufficient sample amount in the case of a small sample amount in separate measurement.

Further, electrodes used in the conventional EIS measuring instrument have a generally cylindrical shape, and as shown in fig. 1, fig. 1 is a schematic structural view of the conventional EIS measuring instrument. When the EIS measuring instrument is used, an additional fixing structure is needed to fix the plurality of electrodes in the figure 1 in a liquid to be measured, the using operation is complicated, and the size of the EIS measuring instrument is large.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a fuse EIS liquid impedance measurement and refractometer's detection device.

The specific scheme is as follows:

a detection device comprises a liquid storage tank, an electrode module, a processing module, a light source module, a reflection module containing a detection area and a photosensitive module,

the detection area is positioned at the bottom of the liquid storage tank, and the liquid storage tank is used for containing liquid to be detected;

the light source module is used for emitting light beams to the detection area of the reflection module, the photosensitive module is used for forming a photosensitive image on at least part of the light beams totally reflected by the reflection module, and the processing module is used for determining the refractive index of the liquid to be detected according to the photosensitive image;

the electrode module comprises at least two electrodes which are arranged in the liquid storage tank and positioned around the detection area, and is used for contacting with the liquid to be detected in the liquid storage tank; the processing module is used for applying an electric signal to at least one electrode in the electrode module, acquiring the electric signal of the at least one electrode in the electrode module, and determining the electrochemical impedance spectroscopy EIS of the liquid to be detected according to the applied electric signal and the acquired electric signal.

Optionally, the at least two electrodes are in a shape of a sheet, and are laid at the bottom of the reservoir and surround the detection area.

Optionally, the at least two electrodes are laid on the surface of the detection region, or the at least two electrodes are laid on the surface of the inner side wall of the reservoir.

Optionally, the at least two electrodes include a counter electrode, a working electrode and a reference electrode, wherein at least one of the size, the position and the shape of the counter electrode and the working electrode are symmetrically arranged, and the distance between the reference electrode and the working electrode is smaller than the distance between the reference electrode and the counter electrode.

Optionally, the at least two electrodes are disposed on a circuit board, and a temperature sensor is disposed on the circuit board.

Optionally, the reservoir is tapered, and a water level indication line is carved in the reservoir.

Optionally, the photosensitive module includes a photosensitive area array, and at least one converging lens is disposed between the reflective module and the photosensitive module, and is configured to converge the light beam totally reflected by the reflective module onto the photosensitive area array.

Optionally, the processing module includes a main control chip and a peripheral circuit built outside the main control chip, where the main control chip is configured to output an ac signal through a DAC provided in the main control chip, and the peripheral circuit is configured to shape the ac signal.

Optionally, the peripheral circuit includes a low-pass filter circuit for performing low-pass filtering on the ac signal output by the main control chip, and a circuit for eliminating a dc bias voltage from an output of the low-pass filter circuit.

Optionally, the processing module is further configured to collect an alternating current signal from the electrode module;

the peripheral circuit also comprises a circuit for respectively carrying out zero-crossing detection on the alternating current signal output by the main control chip and the alternating current signal acquired from the electrode module, and a phase comparison circuit for carrying out phase comparison on the two paths of alternating current signals subjected to zero detection to obtain a phase difference pulse signal.

Optionally, the processing module further includes an analog-to-digital conversion circuit, configured to obtain a duty ratio of the phase difference pulse signal when the frequency of the phase difference pulse signal is greater than 1 kHz; the processing module further comprises a timer for acquiring the duty cycle of the phase difference pulse signal when the frequency of the phase difference pulse signal is not more than 1 kHz.

The utility model provides a detection device measures to liquid and carries out the measurement to soluble solid and insoluble solid in the liquid system through realizing simultaneously refraction measurement and electrochemistry impedance measurement, has improved measuring robustness, and because refraction measurement and impedance measurement adopt the same portion liquid and simultaneous measurement completion that await measuring, the liquid that awaits measuring need not to shift, avoids the sample to receive the possibility of pollution, greatly increased measuring accuracy to measured time has also been shortened.

Drawings

Fig. 1 shows a structural diagram of an electrode used in a conventional EIS measuring instrument.

FIG. 2 shows a schematic view of an embodiment of the detection apparatus of the present application.

Fig. 3 is a schematic diagram showing a positional relationship among the light source module, the reflection module and the light sensing module in the detection apparatus.

Fig. 4 and 5 are schematic structural views of two embodiments of the planar electrode, respectively.

FIG. 6 is a schematic diagram of a partial internal structure of one embodiment of a detection device.

FIG. 7A is a diagram of the logical architecture of one embodiment of a processing module in the detection apparatus of the present application.

Fig. 7B is a logic architecture diagram of one embodiment of a low pass filter circuit in the detection apparatus of the present application.

Fig. 8 is a schematic diagram of a circuit structure of the detection apparatus for amplifying the filtered ac signal output by the main control chip and eliminating the dc bias voltage.

Fig. 9 shows a schematic configuration of a half-wave collating circuit and an amplifying circuit in the detecting device.

Fig. 10 shows a schematic diagram of a zero-cross detection circuit and a phase comparison circuit in the detection apparatus.

Fig. 11 shows input and output schematic diagrams of the phase comparison circuit.

Fig. 12 shows an impedance plot of an aqueous sucrose solution.

Fig. 13 shows the refractive index of water and a 40% aqueous sucrose solution.

Fig. 14 shows a liquid system for milk.

Detailed Description

To further illustrate the embodiments, the present invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. With these references, one of ordinary skill in the art will appreciate other possible embodiments and advantages of the present invention. The components in the drawings are not necessarily to scale, and similar reference numerals are generally used to identify similar components.

The present invention will now be further described with reference to the accompanying drawings and detailed description.

As shown in fig. 2, the present embodiment provides a detection apparatus 20 that can measure EIS of a liquid. The detection device comprises a reservoir (not shown) for containing a liquid to be detected, an electrode module 22 and a processing module 21. Wherein the electrode module 22 comprises at least two electrodes disposed within the reservoir. The processing module is used for applying an alternating current signal (such as a sine wave signal) to at least one electrode in the electrode module and for acquiring an electrical signal on at least one electrode in the electrode module. The processing module 21 is further configured to detect an electrochemical impedance spectroscopy EIS of the liquid to be detected according to the acquired electrical signal.

In one example, the detection device is not only used to detect the EIS of the liquid to be measured, but also to detect the refractive index of the liquid to be measured. Specifically, the detection device further includes a light source module 23, a reflection module 24, and a light sensing module 25. As shown in fig. 3, fig. 3 is a schematic diagram of a positional relationship among the light source module, the reflection module and the light sensing module in the detection apparatus. The reflection module 24 comprises a prism, one surface of which is arranged at the bottom of the reservoir. For convenience of description, the area of the prism surface corresponding to the bottom of the reservoir is referred to as a detection region 241 hereinafter. The light source module 23 is used for emitting a light beam to the detection area 241 of the prism. When the liquid to be measured is filled in the liquid storage tank, and the total reflection condition is satisfied between the liquid to be measured and the prism, a light beam (i.e., a light beam with an incident angle greater than or equal to the total reflection angle) which satisfies the total reflection condition in the light beams emitted from the light source module to the detection area of the prism is totally reflected to the light sensing module 25 by the detection area, and a light beam (i.e., an incident angle less than the total reflection angle) which does not satisfy the total reflection condition is transmitted out from the detection area.

Alternatively, the wavelength of the green portion may be used in the light source module, since the light sensing module 25 is sensitive to the green channel light acceptance. The light emitting device in the light source module can be realized by adopting an LED linear array light source method, and the LED linear array light source can be realized by sticking a plurality of LED chips on a PCB. Because there is the clearance between the inside LED chip unit of LED linear array light source, this can influence the homogeneity of the light of final formation of image, consequently can increase even light piece at the light-emitting side of LED chip and realize the effect of even light, even light piece can adopt such as even light piece that light diffuser plate, various materials made to realize the even of light, finally makes the formation of image also more even, can reach better measuring effect.

In addition, since the exiting of the existing LED chip is at a certain diffusion angle, some non-parallel light rays may affect the measurement accuracy, and some non-parallel light rays may also cause artifacts or some factors interfering with the measurement of the light rays collected by the optical receiver. Generally, the collimating system can collimate the light by other means such as a cylindrical lens, a convex lens, a slit, and the like.

Optionally, the detection device further includes a module for decoupling the exit position and the exit angle of the light source, so that the light beams incident to the detection area at the same angle can be incident to the same position of the light sensing module when being reflected to the light sensing module. Therefore, a sudden brightness change boundary is formed on the photosensitive image detected by the photosensitive module. It can be understood that when the refractive indexes of the liquids to be measured are different, the total reflection angles of the beams totally reflected on the prism are different, and therefore, the positions of the brightness abrupt change boundary lines formed on the photosensitive modules are also different. Therefore, the processing module is also used for calculating the refractive index of the liquid to be measured by detecting the positions of the boundary lines of the brightness picture on the photosensitive image.

The module for decoupling the exit position and the exit angle of the light source in the detection device may be implemented by a slit or a small hole located at the light emitting surface of the light source module, and the slit or the small hole may also be implemented by a collimation system at the exit end of the light source module at the same time. Alternatively, as shown in fig. 3, it may be implemented by a condensing lens 26 between the prism 24 and the photosensitive module 25. The light beam totally reflected by the prism 24 enters the converging lens 26, and is converged on the photosensitive surface of the photosensitive module 25 by the converging lens 26. Compared with the light source module, the small holes are formed in the light emitting surface of the light source module to achieve decoupling of the angle and the position of an incident light beam of the photosensitive linear array in one dimension (namely the direction parallel to the photosensitive linear array), the convergence module is arranged between the prism and the photosensitive module to achieve decoupling in two dimensions, the photosensitive module of the photosensitive surface array is adopted in a matched mode to detect the light beam, more information can be obtained, the accuracy of the refractive index of liquid to be detected is improved, and even more information of the liquid to be detected can be obtained.

Optionally, the photosensitive module 25 includes an optical filter and an optical receiver. Since the optical devices in the optical receiver have different sensitivity degrees to different wavelengths, the optical filter functions to preferentially select the light source within the wavelength range from the light beams emitted by the light source module. Secondly, in order to filter out other wavelengths of stray light entering the optical receiver in the environment, the stray light may be due to other light sources, such as other wavelengths of light entering the optical system from the sunlight, and the like.

The optical receiver mainly comprises a CMOS, a CCD or other optical receiving components, and can effectively receive the light emitted by the light source and reflected by the prism system, so as to obtain effective light information for a subsequent measuring system to perform relevant measurement. The optical receiver can adopt an area array CMOS to detect the image sensor, so that the cost is lower, the accuracy is higher, the installation requirement is reduced, and the things which can not be realized by a plurality of one-dimensional sensors can be realized, such as improving the accuracy, enhancing the anti-interference capability, adding other measurement functions and the like; moreover, even if bubbles exist at the detection area of the prism or the liquid to be measured does not completely cover the total reflection interface, the brightness abrupt change boundary can still be clearly distinguished.

In one example, the electrode module 22 includes at least two electrodes affixed to the interior surface of the reservoir and arranged around the detection region 241. Because the voltage and the current need to be measured respectively by the double electrodes, and the voltage fluctuates to some extent when the current flows, the measurement result is not accurate enough, and the measurement accuracy can be improved by adopting the structure of the three electrodes. The electrode module can determine a system of measuring electrodes according to a system of measuring liquid during impedance measurement, and generally comprises three electrode systems, namely a two-electrode system, a three-electrode system and a four-electrode system. When impedance measurement is carried out, if the electrode potential of the auxiliary electrode is determined to be unchanged or change can be ignored in the test process, a reference electrode is not needed, and the measurement can be carried out by adopting a two-electrode system.

In order to reduce the influence of the electrode potentials of the working electrode and the auxiliary electrode (counter electrode) changing during the test, a three-electrode system is used, which has a working electrode (research electrode), a reference electrode and an auxiliary electrode (counter electrode) for measuring and monitoring the potential difference between the reference electrode and the working electrode with high input impedance, almost no current passes through the reference electrode, and current passes between the working electrode and the auxiliary electrode.

In order to overcome the influence of electrode polarization and environmental fluctuation, a four-electrode test system can be adopted, a pair of outer electrodes is utilized to introduce exciting current into liquid, the voltage on a pair of inner electrodes is measured, and an alternating current impedance method is mainly adopted to test the resistance.

Optionally, each electrode is in a planar sheet shape and is laid at the bottom of the liquid storage tank. Compare prior art's spatial structure's electrode, each electrode in this application adopts planar structure to set up in the bottom of liquid groove, can simplify the design and the processing degree of difficulty of the waterproof construction to the electrode module, and the electric field that distributes in the liquid is more even in the bottom distribution moreover, more is favorable to the collection of electrode pair signal.

The material of the electrode can be a platinum electrode, a titanium electrode, a carbon electrode and other metal compound electrodes. There are various implementations of the electrodes. In order to achieve a small integration of the planar electrodes, the electrodes may optionally be integrated on a circuit board. The circuit board can be a flexible circuit board of FPC technology, or a PCB circuit board, or an aluminum-based circuit board. The PCB can be made of FR4 resin and is subjected to metallization edge covering treatment. Wherein, the thickness of the flexible circuit board of the FPC technology can be 0.09mm or even thinner.

Methods of making planar electrodes are various. For example, a metal sheet is fixed on the surface of the circuit board by means of adhesive or the like as an electrode, and contacts on the circuit board are welded to the metal sheet to conduct the electrodes, or the metal sheet is adhered to the circuit board by means of conductive adhesive to make the metal sheet and the contacts on the circuit board contact and conduct. For another example, the bare copper sheet of the circuit board is used for gold deposition process, and a layer of nickel-gold is plated to form the electrode, the nickel-gold has the advantages of corrosion resistance and long service life, and the scheme can control the thickness of the electrode to be very thin. The FPC copper sheet has mature process, the thickness can be controlled within 0.15mm, and the PI material of the FPC cover film is non-toxic, so that the FPC copper sheet can be used for manufacturing tableware and medical appliances, and a detection device is convenient to use in some catering or medical fields. Also for example, each electrode may be implemented using copper plating. When the circuit board is a flexible circuit board of an FPC (flexible printed circuit) process, the circuit board can be reinforced by sticking a plurality of stainless steel sheets on the circuit board, and exposed copper is arranged on the steel sheets to form contacts so as to form a plurality of planar electrodes. The electrodes can be made of the same or different materials, and the problem that the accuracy of a measuring result is reduced due to different corrosion degrees of different materials during measurement can be solved by using the same materials.

As shown in fig. 4 and 5, fig. 4 and 5 are schematic structural views of two embodiments of the planar electrode, respectively. In both illustrations, the circuit board 40 is provided with a through hole 41, and the through hole 41 is located at the bottom of the reservoir corresponding to the detection area of the prism when the circuit board 40 is fixed on the surface of the prism.

Around the through hole 41, three metal sheets 42, 43 and 44 are attached for realizing three electrodes, respectively, and a separator plastic sheet 45 is attached between any two metal sheets. The shapes of the foils may be different when the two illustrations are different. The edge of the foil may be aligned with the edge of the circuit board in fig. 4 and the foil is looped around the through hole 41 in fig. 5, the edge being located within the edge of the circuit board. Optionally, as shown in fig. 4 and 5, a temperature sensor 46 is further disposed on the circuit board, and the heat is conducted to the lower side of the temperature sensor through the large area of copper under the planar electrode, so that the temperature sensor can directly measure the temperature conducted by the planar electrode. Since the refractive index of the liquid shifts with a change in temperature, a deviation occurs in determining the solid soluble content of the liquid from the refractive index of the liquid. The temperature of the liquid to be measured, which is measured by the temperature sensor arranged in the detection device, can be convenient for the processing module to correct the measurement result according to the temperature when calculating the refractive index of the liquid to be measured, so that the accuracy of refractive index measurement is improved; the electrode simultaneously plays a role of a heat conducting medium, so that the electrode has good heat conductivity, the temperature sensor can more accurately measure the temperature of the liquid to be measured, and the accuracy of the temperature sensor in measuring the temperature of the liquid to be measured is improved.

When the electrode module has a three-electrode structure, the CE counter electrode 43, the SE working electrode 42, and the RE reference electrode 44 are provided. Optionally, at least one of the size, the position, and the shape of the CE counter electrode 43 and the SE working electrode 42 are symmetrically arranged, and the distance between the RE reference electrode 44 and the SE working electrode 42 is smaller than the distance between the RE reference electrode 44 and the CE counter electrode 43, so as to improve the performance of the electrode module. When the electrode module is a dual-electrode structure, optionally, the two electrodes are symmetrically arranged. When the electrode module is of a four-electrode structure, optionally, the four electrodes may be symmetrically arranged in pairs, and the symmetrical arrangement may be a symmetrical arrangement of at least one of size, position and shape.

Fig. 6 is a schematic view of a part of the internal structure of one embodiment of the detecting device, as shown in fig. 6. Optionally, the reservoir 61 is tapered to improve ease of cleaning the reservoir. Optionally, a scribing line is further arranged in the liquid storage tank, and is used for reminding a user that the liquid to be detected exceeds the scribing line when the liquid to be detected is placed upside down in the liquid storage tank, so that the amount of the liquid required by the detection device when the refractive index and the EIS of the liquid to be detected are measured is ensured. Optionally, a light-transmitting waterproof layer covering the electrode module and the detection region is further disposed at the bottom of the liquid storage tank.

Each electrode in the electrode module 62 extends into the liquid storage tank, the liquid to be measured can form a prism and liquid level interface on the prism 63, and the light is filtered by the optical filter and received by the optical receiver by means of total reflection of the prism and the liquid level interface. The electrodes can be embedded in the surface of the prism and extend into the liquid storage tank, or laid on the detection area of the prism, or laid on the inner peripheral wall of the liquid storage tank in a surrounding manner, or penetrated into the liquid storage tank from the peripheral wall of the liquid storage tank, and the like.

When the liquid to be measured is filled in the liquid storage tank, the counter electrode and the reference electrode are main nodes for measuring potential and impedance, so that potential or current with certain frequency and amplitude is required to be applied to the working electrode. The signal excited on the electrode can be a static direct current signal, which can measure measurement information such as conductivity, static potential and the like; or an alternating current signal excited according to a certain frequency and amplitude, wherein the frequency range can be 0.0001Hz-10MHz, and the amplitude can be-10V-10V, so that the response parameters of the potential and the impedance of the liquid under different frequencies can be measured.

The processing module excites a sinusoidal signal with certain frequency width and amplitude to the liquid to be measured through at least one electrode in the electrode module, multi-dimensional information is formed through detecting the impedance, the potential and the phase of the liquid between the electrodes and through the relation between the electrodes and the frequency, the obtained multi-dimensional information and the signal measured by the optical receiver instrument can describe the property of the liquid together, the property of the liquid to be measured can be judged more accurately, and the refraction measurement and the impedance measurement are completed by adopting the same liquid to be measured and simultaneously, the liquid to be measured does not need to be transferred, the possibility of sample pollution is avoided, the measurement accuracy is greatly increased, and the measurement time is also shortened.

There are many implementations of the signal stimulus. For example, the ac signal may be directly output from a Digital to Analog Converter (DAC) chip controlled by a main control chip, or may be directly output from a modulation resonant circuit. The DAC chip can generate sine wave signals with high frequency, such as sine waves of 1Mhz, but the cost is high, the model selection is difficult, the problem is easy to occur at the end of a supply link in production, the modulation resonant circuit can realize that the frequency of output alternating current signals is adjustable, but the realization difficulty is high, and the cost is difficult to control and realize miniaturization in production due to the complex and large circuit structure.

In one example, as shown in FIG. 7, FIG. 7 is a diagram of the logical architecture of one embodiment of a processing module in the detection apparatus of the present application. Optionally, in the application, the processing module includes a single chip, and the DAC provided in the single chip is used as a signal excitation source to output an alternating current signal, so that the cost can be greatly reduced and the miniaturization can be realized. In one example, the single chip microcomputer comprises a main control chip ESP32S2. However, the waveform of the ac signal output from the DAC of the main control chip ESP32S2 is likely to be distorted after the frequency exceeds 100 kHz. Optionally, the processing module further includes a low-pass filter circuit for processing the ac signal output by the DAC in the main control chip, so as to make the waveform reach the standard. Alternatively, the low-pass filter circuit may be a butterworth low-pass filter, as shown in fig. 7B, and fig. 7B is a schematic structural diagram of an example of the low-pass filter circuit, and the ac signal output from the DAC is input to the circuit from the port ESP _ SIN _ DAC in fig. 7B for low-pass filtering. In some examples, the ac signal processed by the low pass filter may have a dc bias voltage, and optionally, the processing module further includes a cancellation bias circuit for canceling the dc bias voltage from the ac signal processed by the low pass filter. Optionally, the processing module may further include an amplifier, configured to amplify the ac signal output by the main control chip and output the amplified ac signal to the electrode module, for example, to an electrode CE in the electrode module. As shown in fig. 8, fig. 8 is a schematic diagram of a circuit structure of the detection apparatus for amplifying the filtered ac signal output by the main control chip and eliminating the dc bias voltage. After being filtered, the ac signal output BY the main control chip is input from CE _ SIN _ BY _ OFFSET to the OFFSET operational amplifier circuit 81 and the power amplifier 82, and then output to the electrode RE and the electrode CE. Through utilizing the DAC output alternating current signal from taking in the singlechip, and set up a plurality of peripheral circuits outside the singlechip and handle the alternating current signal of main control chip output in this application, can export high-frequency alternating current signal, compare and directly adopt the DAC chip can greatly reduced cost, and compare modulation resonant circuit and can reduce the volume, realize the miniaturization.

The processing module is also used for collecting signals generated by the electrodes. For example, in a three-electrode configuration, the processing module is connected to the electrode WE for collecting electrical signals on the electrode WE. Because the collected electric signals are mostly Analog quantity signals, optionally, the processing module further includes an Analog-to-digital converter (ADC) circuit for converting the Analog quantity signals into digital signals and inputting the digital signals into the processing module. The ADC may be a self-contained ADC within a single chip. And the processing module calculates the impedance according to the maximum value acquired by the ADC, and further measures the change of the impedance along with the frequency of the alternating current signal. Optionally, the operational amplifier resistor in the ADC circuit is an adjustable resistor, so that the range of the ADC can be changed, and the maximum value obtained by the ADC circuit can be adjusted.

Optionally, the processing module further includes an amplifying circuit on the signal link of the collecting electrode module, and is configured to amplify the ac signal collected by the electrode module before the ADC circuit, and then half-wave rectify the amplified ac signal and input the rectified ac signal to the ADC in the single chip microcomputer. As shown in fig. 9, fig. 9 is a schematic diagram of a half-wave collating circuit and an amplifying circuit in the detection apparatus. The electrode WE is sequentially connected with the trans-group amplifying circuit 91 and the amplifying circuit 92, and an electric signal on the electrode WE is amplified by the trans-group amplifying circuit 91 and the amplifying circuit 92, then input to the half-wave rectifying circuit 93 for half-wave rectification, and then input to the ADC through the WE _ SIN _ POS.

The processing module is further used for acquiring the phase change of the alternating current signal generated by the DAC and the alternating current signal collected by the ADC. Optionally, the ADC circuit may be implemented by a high-precision ADC chip, so that the ADC chip may acquire a complete waveform for the ac signal, but the sampling capability of the ADC chip is very high, which results in high cost. Optionally, in this embodiment, the processing module is further configured to perform zero-crossing detection on the alternating current signal generated by the DAC and the alternating current signal acquired by the electrode module, and perform logical and on the two signals after the zero-crossing detection to obtain a phase difference pulse signal, where a duty ratio of the phase difference pulse signal represents a phase difference of the two signals.

As shown IN fig. 10 and 11, the ac signal generated by the DAC and the ac signal collected by the electrode module are respectively input to the zero-cross detection circuit 101 and the zero-cross detection circuit 102 from two ports SIN _ IN1 and SIN _ IN2, and the two positive voltage partial pulses obtained are input to the phase detection circuit 103 for phase comparison, for example, logical and operation (as shown IN fig. 11) to obtain a phase difference pulse. Alternatively, the signal input from the SIN _ IN1 port may be a signal output from the CE _ SIN port IN the circuit diagram shown IN fig. 8, and the signal input from the SIN _ IN2 port may be a signal output from the WE _ SIN port IN the circuit diagram shown IN fig. 9.

The processing module is also used for carrying out positive and negative phase detection and PWM duty ratio measurement on the phase difference pulse signals. Because the duty ratio and the phase of the phase difference pulse are in a linear relation, when the frequency of the phase difference pulse signal is more than 1Khz, the phase difference pulse signal can be subjected to RC low-pass filtering, and the phase difference pulse is converted into a direct current signal for detection. The PWM duty cycle of the pulse signal is then calculated based on the filtered voltage value and a preset scaling function. The relationship between the voltage value and the PWM duty cycle at different frequencies may be non-linear, and the functional relationship between the filtered voltage value and the PWM duty cycle of the pulse signal may be pre-calculated and stored in the processing module. When the frequency of the phase difference pulse signal is less than 1Khz, the PWM duty ratio of the phase difference pulse signal can be measured by GPIO edge capture or PCNT pulse capture, or can be detected by a timer of a singlechip. Therefore, the phase measurement precision can be improved and can reach +/-0.1 degree. Compared with an ADC chip with high precision, the method has the advantages that the circuit cost can be greatly reduced by acquiring the duty ratio after zero-crossing detection and logic and calculation of two paths of signals.

The following illustrates the advantages of the detection apparatus provided by the present embodiment over existing refractometers and EIS impedance measurements.

Example 1

In a non-conductive liquid system, because liquid is not ionized, such as a sucrose aqueous solution, in the case of preparing the sucrose aqueous solution with ultrapure water, because other ionized ions are not present in the sucrose aqueous solution except for sucrose molecules, sucrose exists in a state of molecular crystals, and no ionization condition exists, information displayed by the sucrose aqueous solution during electrical impedance measurement is not greatly different from that of water (see fig. 12 for an impedance graph of the sucrose aqueous solution), and thus the concentration of sucrose water cannot be judged by simply measuring electrical impedance.

However, the concentration of the sucrose aqueous solution causes a change in the refractive index of the liquid, and thus a very large difference is exhibited in the measurement results of the refractometer (the refractive index of water and a 40% sucrose aqueous solution is shown in fig. 13, and the left part is water and the right part is a 40% sucrose aqueous solution in fig. 12).

It can therefore be seen that the refractometer can detect the optical properties of the liquid to achieve detection of the liquid under wakefulness which is not electrochemically measurable.

Therefore, by simultaneously carrying out electrochemical property measurement and refraction measurement on the solution to be measured, the robustness of the measurement result can be greatly improved. For another example, honey in the market is classified more, but the honey is not very different in concentration, for example, honey of different flowers such as sophora flower honey is about 75% sugar degree. When the honey is measured, the measurement result of the refractometer cannot directly reflect the specific variety of the honey, but the electrochemical impedance measurement method can directly reflect the conditions of other components except sugar in the honey, and the measurement mode can more quickly distinguish the quality and variety of the honey.

Example 2

There are also a number of soluble ionic systems (calcium, potassium, phosphorus, etc.) and insoluble adipocytes, proteins, etc. in milk, these insoluble substances also being very important nutrient elements in milk. Soluble solids contained in milk can only be measured by refractometry, but the parameters of most interest to milk are protein content and fat content. The milk can be regarded as a liquid system as in fig. 14, in which the grey parts represent the fat cells which are liquid and the circled parts represent the fat cells in fig. 14. When an impedance meter is used to excite electrical signals of different frequencies (0.01 Hz-100000 Hz), (i) is often the path for low frequency currents, and (ii) is the path for high frequency currents. Therefore, two peaks of the corresponding impedance at different frequencies can be detected, so that the amount of the fat component in the milk can be judged. Even specific electrodes can be manufactured to detect specific elements in the milk, such as CPE electrodes can specifically react with serum in the milk and be reflected on an electrochemical impedance spectrum.

The detection device fusing EIS liquid impedance measurement and the refractometer provided by the specific embodiment has the following advantages:

1. the measurement of soluble solids and insoluble solids in a liquid system is carried out on the liquid by simultaneously realizing refraction measurement and electrochemical impedance measurement, so that the measurement robustness is improved; especially for concentration measurements and species measurements of liquids.

2. And performing mutual complementary measurement by using the electrochemical characteristic and the optical characteristic, and when the optical characteristic cannot be distinguished, distinguishing by using the electrochemical characteristic to realize complementary measurement.

3. When the liquid is capable of being measured for both measurement modes, the advantages of a certain measurement scheme can be utilized to achieve a more accurate measurement.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (11)

1. A detection device, characterized by: comprises a liquid storage tank, an electrode module, a processing module, a light source module, a reflecting module containing a detection area and a photosensitive module, wherein,

the detection area is positioned at the bottom of the liquid storage tank, and the liquid storage tank is used for accommodating liquid to be detected;

the light source module is used for emitting light beams to the detection area of the reflection module, the photosensitive module is used for forming a photosensitive image on at least part of the light beams totally reflected by the reflection module, and the processing module is used for determining the refractive index of the liquid to be detected according to the photosensitive image;

the electrode module comprises at least two electrodes which are arranged in the liquid storage tank and positioned around the detection area, and is used for contacting with the liquid to be detected in the liquid storage tank; the processing module is used for applying an electric signal to at least one electrode in the electrode module, acquiring the electric signal of the at least one electrode in the electrode module, and determining the electrochemical impedance spectroscopy EIS of the liquid to be detected according to the applied electric signal and the acquired electric signal.

2. The detection device according to claim 1, wherein the at least two electrodes are in the form of a sheet, and are disposed on the bottom of the reservoir and around the detection region.

3. The detection device of claim 2, wherein the at least two electrodes are laid flat on the surface of the detection zone or the at least two electrodes are laid on the surface of the inner side wall of the reservoir.

4. The detection device of claim 1, wherein the at least two electrodes comprise a counter electrode, a working electrode, and a reference electrode, wherein at least one of the size, position, and shape of the counter electrode and the working electrode are symmetrically arranged, and the distance between the reference electrode and the working electrode is less than the distance between the reference electrode and the counter electrode.

5. The sensing device of claim 1, wherein the at least two electrodes are disposed on a circuit board, and wherein a temperature sensor is disposed on the circuit board.

6. The detecting device for detecting the water level of the motor vehicle seat cushion according to claim 1, wherein the liquid storage tank is in a conical shape, and a water level prompt line is carved in the liquid storage tank.

7. The detecting device according to claim 1, wherein the photosensitive module includes a photosensitive area array, and at least one converging lens is disposed between the reflective module and the photosensitive module for converging the light beams totally reflected by the reflective module onto the photosensitive area array.

8. The detection device according to claim 1, wherein the processing module includes a main control chip and a peripheral circuit built outside the main control chip, wherein the main control chip is configured to output an ac signal through a DAC thereof, and the peripheral circuit is configured to shape the ac signal.

9. The detection device according to claim 8, wherein the peripheral circuit comprises a low pass filter circuit for low pass filtering the ac signal output by the main control chip, and a circuit for removing the dc bias voltage from the output of the low pass filter circuit.

10. The detection device of claim 8, wherein the processing module is further configured to collect an alternating current signal from the electrode module; the peripheral circuit also comprises a circuit for respectively carrying out zero-crossing detection on the alternating current signal output by the main control chip and the alternating current signal acquired from the electrode module, and a phase comparison circuit for carrying out phase comparison on the two paths of alternating current signals subjected to zero detection to obtain a phase difference pulse signal.

11. The detection apparatus according to claim 10, wherein the processing module further comprises an analog-to-digital conversion circuit for acquiring a duty cycle of the phase difference pulse signal when the frequency of the phase difference pulse signal is greater than 1 kHz; the processing module further comprises a timer for acquiring the duty cycle of the phase difference pulse signal when the frequency of the phase difference pulse signal is not more than 1 kHz.

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