An
automatic urine analyzer is a medical device used to detect and analyze urine components and is widely used in clinical diagnosis and health monitoring. Its research progress and working principles are as follows:
1. A brief history of the development of urine analyzers
In 400 BC, Hippocrates noticed fever. Changes in urine color and odor.
18th-19th century - Microscopic urine examination and urine chemical analysis began.
In 1827, Bright first used urine testing for patient diagnosis and care.
1930 - First urine spot test on filter paper.
1956 - Ames and Lilly companies in the United States created urine glucose test strips almost simultaneously.
1960-80 - Multi-parameter urine test strips began to be used clinically.
In the 1970s, the first urine chemistry analyzer came out.
After the 1980s, semi-automatic and fully-automatic urine dry chemistry analyzers began to be gradually used in clinical practice.
In the mid-to-late 1980s, South Korea's photoelectric conversion element CCD (charge coupled device) produced the Uriscan-S300 11-item urine analyzer.
In 1985, China introduced the production technology and equipment of the MA-4210 urine analyzer and special reagent strips from Japan.
In 1990, all urine analyzers were domestically produced.
In 1992, 10-item urine analyzer and special reagent strips were launched.
In 1994, the Uritest-100 10-item urine analyzer and special reagent strip were launched.
In the first half of 1997, the Uritest-200 11-item urine analyzer and special reagent belt were launched.
2. Classification of urine analyzers
According to the working method, it can be divided into: liquid urine analyzer and dry urine analyzer
According to the classification of test items, it can be divided into:
(1) 8-item urine analyzer: MA-4210 type (Japan and China) PRO, GLU, PH, KET, BIL, UBG, ERY, NIT;
(2) 9-item urine analyzer: RL-9 type (Germany) PRO, GLU, PH, KET, BIL, UBG, ERY, NIT, LEU;
(3) 10 items of urine analyzers: MIDITRON (Germany), CLINITEK 200 (USA), Uritest-100 (domestic) PRO, GLU, PH, KET, BIL, UBG, ERY, NIT, LEU, BG;
(4) 11 urine analyzers: CLINITEK Atlas type (USA), URISCAN-S300 type (South Korea), Uritest-200 type (domestic) PRO, GLU, PH, KET, BIL, UBG, ERY, NIT, LEU, BG, color or vitamin C;
(5) 12-item urine analyzer: CLINITEK 500 (USA), Aution MaxTM AX-4280 (Japan), Bollingmann/Roche Urysis 2400, PRO, GLU, PH, KET, BIL, UBG, ERY , NIT, LEU, BG, color and turbidity.
It can be classified according to the degree of automation:
Semi-automatic urine analyzer: MIDITRON type (Germany), CLINITEK 200 type (USA), URISCAN-S300 type (South Korea), Uritest-200 type (China), Uritest-100 type (China) including 8 items of urine and 9 items of urine , urine 10 items, urine 11 items.
Fully automatic urine analyzer: SUPERTRON type (Germany), CLINITEK Atlas type, (USA), Aution MaxTM AX-4280 type (Japan), Bolingmann/Roche Urysis 2400 type, including urine 10 items, urine 11 items, 12 items of urine.
3. Working principle
Reagent belt structure:
The first layer of nylon membrane: plays a protective role to prevent macromolecular substances from contaminating the reaction.
The second layer of velvet layer: It includes an iodate layer and a reagent layer. The iodate layer can destroy interfering substances such as vitamin C. The reagent layer contains reagent components, which mainly react chemically with the substances measured in urine to produce color changes. .
The third layer of water-absorbent layer: allows urine to be immersed evenly and quickly, and can inhibit the flow of urine to the adjacent reaction area.
The fourth layer: a plastic sheet that is not wetted by urine as a support.
The reaction principle of the reagent strip
1) pH measurement: Using a composite indicator composed of methyl red and bromothymol blue, the color changes from orange and green to blue at pH 4.5- pH 9.
2) Urine protein measurement: using the principle of pH indicator protein error. Reference method: Sulfosalicylic acid method.
3) Urine glucose measurement: A glucose oxidase method. B copper reduction method
4) Urine ketone body determination: sodium nitrosoferricyanide method
5) Urine occult blood measurement: The heme in free hemoglobin, dissolved red blood cells or myoglobin has a peroxidase-like effect, which can catalyze hydrogen peroxide to release new ecological oxygen, oxidize the chromogen and develop color, and its color depth Related to hemoglobin content.
6) Urine bilirubin determination: using the principle of diazo reaction method.
7) Urobilinogen determination: using the principle of Ehrlich diazo reaction method.
8) Urine nitrite measurement: It uses the property of certain bacteria to reduce nitrate in urine into nitrite. The color change is proportional to the number of bacteria, and a positive result indicates that the number of bacteria in the urine is 105/ml.
9) Urine leukocyte measurement: Utilize the principle that the lipase of neutrophils can hydrolyze indolephenol to generate indolephenol and organic acid, and the indolephenol can be further oxidized into indigo; or the principle that indoxylphenol and diazonium salt react to form diazo The color develops due to pigment, and the depth of the color is related to the amount of granulocytes.
10) Urine specific density determination: Determination of specific density based on the pKa of a certain pre-treated polyelectrolyte in a solution with a certain ion concentration. Reference method: Refractometer method.
11) Determination of urine vitamin C: Use phosphomolybdate buffer or methyl green to react with vitamin C in urine to form molybdenum blue. The depth of the color is related to the vitamin C content in urine.
Application of reagent strips
Different models of urine analyzers generally use their own dedicated reagent strips. There is also one more blank block and one more reference block.
Measurement principle
After immersing the reagent strip in urine, except for the blank strip, the rest of the reagent strips changed color due to chemical reactions with the urine. The color depth of the reagent block is proportional to the reflectivity of light, and the color depth is proportional to the concentration of individual components in the urine. As long as the reflectivity of light is measured, the concentration of various components in urine can be determined. It is generally controlled by a microcomputer and uses a sphere calculator to receive dual-wavelength reflected light to measure the color change on the reagent strip for semi-quantitative measurement. The measurement wavelength is the sensitive characteristic wavelength of the tested agent block, and the other is the reference wavelength, which is the insensitive wavelength of the tested agent block and is used to eliminate the influence of background light and other stray light.
4. Structure and composition of the instrument
The mechanical system includes a transmission device, a sampling device, a sample adding device, and a measurement and testing device.
The optical system includes light source, monochrome processing, and photoelectric conversion. Light irradiates the surface of the reaction area to produce reflected light, and the intensity of the reflected light is proportional to the reaction color of each item. The reflected light of different intensities is then converted into electrical signals by photoelectric conversion devices for processing.
MA-4210 (Japan) and Uritest-100/200 (China) urine analyzers use white light emitted by a light source lamp (halogen lamp) to illuminate the reagent belt through the light tube of the sphere integrator, and the reagent belt reflects the light. The color filter is passed through the spherical integrator to obtain monochromatic light of a specific wavelength, which is illuminated on the photodiode to achieve photoelectric conversion.
The MIDITRON urine analyzer uses a light-emitting diode (LED) that can emit specific wavelengths as the detection light source. Each detection head has three photodiodes of different wavelengths, corresponding to the specific detection items on the reagent belt, which are red and orange. , green monochrome (660nm, 620nm, 555nm), which illuminate the reaction area at 60° relative to the detection surface. The photodiode as a photoelectric conversion device is installed vertically above the reaction area, and receives reflected light while detecting light irradiation. Because it is close to the reaction area, no light path is needed for conduction, so there is no signal attenuation. This allows a strong optical signal to be obtained by irradiating a photodiode with a small light intensity.
The CLINTEK200 urine analyzer uses a high-brightness tungsten halogen lamp as the light source, which is transmitted to two detection heads through optical fibers. Each detection head has 11 detection positions, and the incident light shines on the reaction area at an angle of 45°. There is also a set of optical fibers fixed directly above the reaction area. The reflected light is transmitted to the optical filter for splitting (510~690nm is divided into 10 wavelengths). The monochromated optical signal is then converted into an electrical signal by a photodiode.
URISCAN-S300 urine analyzer uses the most advanced optical element CCD technology for photoelectric conversion. It decomposes the reflected light into the three primary colors of red, green and blue (RGB: 610nm, 540nm, 460 nm), and divides each of the three primary colors into 2592 pigments, so that the entire reflected light is divided into 7776 pigments, which can accurately distinguish colors Various small changes from shallow to deep. CCD devices have good photoelectric conversion characteristics, from visible light to near-infrared light. Usually a high-pressure xenon lamp is used as the light source, which is characterized by a luminous spectrum close to sunlight; a narrow discharge path, which can form a linear light source or a point light source; and high luminous efficiency.
Circuit system: The photodetector converts the intensity of the light signal reflected by the reagent strip into the size of the electrical signal, sends it to the preamplifier for amplification, and then sends the electrical signal to the voltage/frequency converter to convert the sent analog signal After the size is converted into a digital signal, it is sent to the counting circuit for counting. The counted signal is sent to the CPU unit. The CPU calculates and processes the signal and sends it to the instrument's built-in thermal printer, which prints out the test results.
5. Maintenance
After a new instrument is installed, or after any major maintenance:
① First, the urine analyzer should be calibrated. The purpose of calibration is to make the instrument enter the state specified by the manufacturer. The urinalysis experiment can only be carried out when the calibration is passed, otherwise the machine will be shut down.
②The accuracy of the urine analyzer and reagent strips should be evaluated.
③ Use traditional methods and urine analyzer measurements for comparative analysis to evaluate the sensitivity and specificity of the urine analyzer.
④ Understand the test range of each test indicator of the instrument, and establish the reference value range of the instrument for normal people.
Precautions:
(1) Keep the instrument clean to maintain good operation.
(2) Make sure to use a clean sampling cup.
(3) Use fresh mixed urine. After collecting the specimen, the inspection generally does not exceed 2 hours.
(4) Different types of urine analyzers use different urine test strips. Do not open the bottle cap containing the reagent strip when the test strip changes from refrigerated temperature to room temperature. Cap the bottle immediately after each use to prevent the reagent tape from getting damp and deteriorating.
(5) The time for the reagent strip to be immersed in the urine sample is 2 seconds. Urine samples with excessive reagent strips should be sucked away with filter paper. All reagent blocks, including blank blocks, must be immersed in urine.
(6) The optimal temperature for using the instrument should be room temperature between 20°C and 25°C. Urine specimens and reagent strips should also be maintained within this temperature range.
(7) When viewing the instrument test results, due to the large difference in the result grades of various urine analyzer designs, the symbolic code results cannot be explained alone. The analysis must be combined with semi-quantitative values to avoid insufficient reporting methods of qualitative results. may cause confusion in clinical interpretation.
maintenance
Routine maintenance of urine analyzer
In routine work, certain operating procedures must be strictly followed, otherwise the experimental results will be affected by improper use.
① Before operating the urine analyzer, you should carefully read the analyzer instructions and urine reagent belt instructions; each urine analyzer should establish operating procedures and operate according to them.
② There should be a dedicated person responsible for the urine analyzer, establish a special instrument registration book, and register the daily instrument operation, problems, and maintenance and repairs one by one.
③ Before starting the measurement every day, the instrument must be fully inspected (various devices and waste liquid devices, printing paper conditions, and whether the instrument needs calibration, etc.), and the instrument can only be turned on after confirmation. After the measurement is completed, the instrument must be thoroughly cleaned and maintained.
④Urine reagent strips that have been opened but not used should be put into the bottle immediately and capped.
Maintenance of urine analyzer
①Daily maintenance: After daily use, it should be cleaned and rinsed with water.
②Weekly or monthly maintenance: Weekly or monthly maintenance of various types of urine analyzers depends on the specific conditions of the instrument.
Common faults of urine analyzers
Instrument failures are divided into inevitable failures and accidental failures. Inevitable failure refers to the aging of the performance and structure of various components and parts after long-term use, causing the instrument to be unable to work normally; accidental failure refers to the sudden occurrence of various components and structures due to the influence of external conditions. The properties change and the instrument cannot work normally. The causes of urine analyzer failure are divided into the following categories.
(1) Failure caused by humans
This type of failure is caused by improper operation, usually caused by the operator being unskilled or not paying attention to the use procedures. A minor fault may cause the instrument to not work properly, or a serious fault may damage the instrument. Therefore, before operation, you must read the user manual carefully, understand the correct operating procedures, and act with caution to reduce the occurrence of such failures.
(2) Failures caused by quality defects in equipment
This type of failure refers to failures caused by poor quality of instrument components, unreasonable design, and negligence in the assembly process.
(3) Failure after long-term use
This type of failure is related to the service life of components. It is caused by the aging of various components, so it is an inevitable failure, such as the aging of optoelectronic devices and displays, the gradual wear and tear of the transmission mechanical system, etc.
(4) Failure caused by external factors
This type of failure is caused by the environmental conditions of the instrument and equipment not meeting the requirements, and is often the main cause of instrument failure. Generally refers to voltage, temperature, electric field, magnetic field and vibration, etc.
6. Development direction of automatic urine analyzer
The future research direction of automatic urine analyzers should reduce costs, increase the degree of automation, integrate urine dry chemical analysis and tangible component analysis into an integrated machine, and network with the hospital's information system, so that the laboratory can better serve clinical medical care.
