CN2052263U - Miniature physiological-parameter instrument for body fluid - Google Patents

Abstract

A miniature human body fluid tester, which can continuously and stably test various physiological parameters by measuring the conductivity of human body fluids, such as human feces, saliva, and various inorganic and organic components in blood. It is non-toxic and non-pathogenic. As a disease screening instrument, it can conduct early diagnosis of kidney disease, liver disease, gallbladder disease and other diseases. It can also be used as an effective tool for natural contraception for women of childbearing age. The instrument is small in size, reliable and convenient to use, and can be used in various medical units, medical colleges, and research institutions, and is especially suitable for portable testing instruments for family health care.

Description

The invention belongs to a medical testing instrument.

Existing technologies and instruments for testing human body fluids are all tested by methods such as physics, chemistry, and microscopy. The testing method is complicated and the cycle is long. And some test methods for special purposes are far from ideal. For example: when temporarily needing to replenish blood to a patient on the operating table, problems such as whether to continue blood transfusion or whether blood transfusion is sufficient cannot be well resolved.

The purpose of the invention is to design an instrument for testing various physiological parameters by measuring the conductivity of the body fluid of the human body. For example, the physiological parameters of various inorganic and organic components in human urine, saliva, blood, etc. can be tested to meet the needs of the increasing development of medical diagnostic technology.

As shown in Figure 1, the application scheme is composed of a self-signal generator, a conductivity cell, a signal processing, a storage comparison, an output display, a regulated power supply, and a voltage loss alarm. The tester consists of an asymmetric astable trigger (also called Multivibrator) generates an asymmetric pulse signal, which is characterized in that the signal pulse is processed so that a negative pulse signal with the same width is generated on the back edge of the pulse, and a self-pulse signal is formed after shaping and level shifting. The final pulse signal with the same amplitude and the same width is then sent to the adder to synthesize the two pulses, and the original asymmetrical pulse signal is synthesized into a bidirectional pulse signal, and then passes through the conductivity cell composed of electrodes and human body fluid to generate a corresponding Current, because the bidirectional pulse signal is a fixed value, and the conductance of the conductance cell varies with the parameters of the body fluid, so that the generated current changes accordingly, and the current passing through the conductance cell is transformed to correspond to the physiological parameters of the body fluid, and then Measure the value at a certain moment and send it to the monitor for display. In order to compare with the last test value, the tester is equipped with a last value storage circuit, and the comparison of the next day's test value is identified by the display of the light-emitting diode.

Description of drawings:

Fig. 1 is the block diagram of this scheme;

Fig. 2 is the schematic circuit diagram of this scheme;

Fig. 3 represents conductance cell model;

Fig. 4 represents equivalent conductance cell model;

Fig. 5 The change curve of saliva conductance during the menstrual cycle.

Further illustrate the structural features of this program with reference to the accompanying drawings:

1.442695／（R₁＋R₂）C₁，t₁

0.693R₁C₁；t₂

0.693R₂C₁，调节R₁，R₂即可方便地改变输出脉冲的占空比及频率。从NE555输出之脉冲波的后沿经R₄C₂并联网络延迟后输入由与非门组成的反相器的输入端使输出滞后（相对于脉冲源输出的脉冲信号）的同宽反向脉冲波。从电路可清楚地看到任何从高电平变到低电平的输入信号都会使其产生一个脉冲信号，脉宽t＝1／9R₄C₂，新脉冲经后二级反相器进行整形，输入双电源放大器A₁以实现电平转移。由于被测体液与电极组成的电导池模型的等效电路，如图4所示为一电阻和电容的并、串联网络，因电容的存在，使充放电过程中产生极化现象会引起测试误差。为了达到适合在体测量且电路简单、价廉、小型化条件下消除电容影响，克服输出电平的基线漂移等不良因素而产生的测试误差，本方案采用了双向脉冲技术，不难证明当正负脉冲脉宽差在1％以内，脉宽T足够窄，电容充电值小于脉冲电压幅值的1％，则其误差在0.02％以内，电容C_X及C_P的干扰就可以排除，对上述要求在脉冲技术中是不难达到的。双脉冲信号的合成方法，是由NE555产生的脉冲波及处理后的滞后同宽脉冲信号输入加法器A₂进行迭加并整形后，即可输出正负对称的双向脉冲信号。A₂为双电源运放，其作用为，1.将二输入脉冲信号迭加；2.电平转移作用，A₂输出的信号为一对称正负电压双向脉冲波。由被测体液和电极构成电导池。电极结构采用盒式结构，盒座为用于牙科材料的有机玻璃制作，由两不锈钢针通入盒座，盒座有一面开有凹槽，使两不锈钢针端部在此槽中露出形成双电极，使加有信号的电极浸入被测体液后感受其电导的变化。为用于人体测试，电极做成小型、并易于清洗。电导池的模形如图3所示，图中符号含义：C_C为导线电容；C_d为双电层内容；R_C为导线电阻；R_X为溶液电阻；Z_f为感应阻抗；C_i为分布电容。其中C_C，C_i与溶液性质、介电常数、电极材料、面积、距离导线的材料，屏蔽状况等有关。忽略微小的导线阻抗，可简化为图4所示的等效电导池模型。其中C_X、C_P分别为综合并、串联电容。从等效模型可知，由于电容的存在，使脉冲加入瞬间会产生电流尖峰值，但其影响仅限于加入瞬间，在反向脉冲的末期，这个尖峰电流的影响早可忽略不计，不难算出在反向脉冲末期通过电导池的电流与体液电导成正比。本方案为了将测得的负脉冲末期与电导池电导对应的电流值得到正确显示，需将该电流值变换成电压值并必须在脉冲间隔时间内其值保持不变，直至下次测量时再改变显示值。为此，电路通过A₂输出的双脉冲信号经电导池得到的电流值通过运放A₃变换为电压值后输入采样保持器LF398信号输入端，来自反相器的脉冲信号经A₄输出至R₁₉、C₃串联电路进行积分后接入A₅当U_C3上升至A₅的开启阀值电压时，A₅输出端输出一正脉冲，该脉冲送采样保持器采样信号输入端使对信号输入端接收到的信号进行采样，采样信号随负脉冲信号的消失而同步消失，进入保持期，直至下一采样脉冲产生。这里，采样信号正确地在需要进行测试时出现，对于本仪器的正确性有着重要的作用，电路中R₃₁为调零电阻，使无测试电流输入时，显示零值。本测试仪的显示装置为数字液晶显示，由采样保持器输出的信号送至CC7106集成块，可直接驱动液晶显示。通过手控调节R₁₀使U′＝U_i，此时D₃、D₄二只LED均不发光，这样就可把当天测试值储存起来，第二次测量时根据LED的状态即可直观地判断出与昨日值的差异。由于电路中电子元件对电压有一定要求，低于规定值时电路将产生畸变，故电源设置具有报警功能。As shown in Figure 2, the utility model utilizes the NE555 timer integrated block to form an asymmetrical astable trigger as the pulse source, and the output frequency and duty cycle are adjustable pulse waves: f

1.442695/(R ₁ +R ₂ ) C ₁ , t ₁

0.693R ₁ C ₁ ; t ₂

0.693R ₂ C ₁ , adjusting R ₁ and R ₂ can easily change the duty cycle and frequency of the output pulse. The trailing edge of the pulse wave output from NE555 is delayed by R ₄ C ₂ parallel network and then input to the input terminal of the inverter composed of NAND gate to make the output lag (relative to the pulse signal output by the pulse source) with the same width reverse pulse Wave. It can be clearly seen from the circuit that any input signal changing from high level to low level will cause it to generate a pulse signal with a pulse width t=1/9R ₄ C ₂ , and the new pulse will be shaped by the second-stage inverter , into dual-supply amplifier _A1 for level shifting. The equivalent circuit of the conductivity cell model composed of the measured body fluid and electrodes is shown in Figure 4 as a parallel and series network of resistors and capacitors. Due to the existence of capacitors, polarization occurs during charging and discharging, which will cause test errors. . In order to eliminate the influence of capacitance under the conditions of simple, cheap and miniaturized circuits suitable for in-body measurement, and overcome the test errors caused by unfavorable factors such as the baseline drift of the output level, this scheme adopts the bidirectional pulse technology, which is not difficult to prove that it is correct If the pulse width difference of the negative pulse is within 1%, the pulse width T is narrow enough, and the charging value of the capacitor is less than 1% of the pulse voltage amplitude, then the error is within 0.02%, and the interference of the capacitor C _X and C _P can be eliminated. The requirements are not difficult to achieve in pulse technology. The method of synthesizing the double pulse signal is that the pulse wave generated by NE555 and the lag after processing are superimposed and shaped by the input adder _A2 of the wide pulse signal, and then the positive and negative symmetrical bidirectional pulse signal can be output. A ₂ is a dual-supply op amp, and its functions are: 1. Superimpose the two input pulse signals; 2. Level shift function, the output signal of A ₂ is a symmetrical positive and negative voltage bidirectional pulse wave. The conductivity cell is composed of the measured body fluid and electrodes. The electrode structure adopts a box structure. The box seat is made of plexiglass used for dental materials. Two stainless steel needles are inserted into the box seat. There is a groove on one side of the box seat, so that the ends of the two stainless steel needles are exposed in this groove to form a double Electrode, so that the electrode with the signal is immersed in the measured body fluid to feel the change of its conductance. For human testing, the electrodes are made small and easy to clean. The model shape of the conductivity cell is shown in Figure 3, and the symbols in the figure mean: C _C is the capacitance of the wire; C _d is the content of the electric double layer; R _C is the resistance of the wire; R _X is the solution resistance; Z _f is the inductive impedance; C _i is the distributed capacitance. Among them, C _C and C _i are related to the properties of the solution, the dielectric constant, the electrode material, the area, the material from the wire, and the shielding condition. Neglecting the tiny wire impedance, it can be simplified to the equivalent conductivity cell model shown in Figure 4. Among them, C _X and C _P are integrated parallel and series capacitors respectively. It can be seen from the equivalent model that due to the existence of capacitance, the current peak value will be generated at the moment of pulse addition, but its influence is limited to the moment of addition. At the end of the reverse pulse, the influence of this peak current can be ignored. It is not difficult to calculate in The current through the conductivity cell at the end of the reverse pulse is proportional to the conductance of the body fluid. In order to correctly display the measured current value corresponding to the conductance of the conductivity cell at the end of the negative pulse, the current value must be converted into a voltage value and must remain unchanged during the pulse interval until the next measurement. Change the displayed value. For this reason, the current value obtained from the _double pulse signal output by the circuit through the conductivity cell through the operational amplifier _A3 is converted into a voltage value and then input to the signal input terminal of the sample holder LF398, and the pulse signal from the inverter is output through _A4 to The series circuit of R ₁₉ and C ₃ is integrated and then connected to A _5. When U _C3 rises to the opening threshold voltage of A ₅ , the output terminal of A ₅ outputs a positive pulse, which is sent to the sampling signal input terminal of the sample holder to make the signal The signal received at the input terminal is sampled, and the sampling signal disappears synchronously with the disappearance of the negative pulse signal, and enters the hold period until the next sampling pulse is generated. Here, it is important for the correctness of the instrument that the sampling signal appears correctly when the test is required. R ₃₁ in the circuit is a zero-adjusting resistor, so that when there is no test current input, it will display a zero value. The display device of this tester is a digital liquid crystal display, and the signal output by the sample holder is sent to the CC7106 integrated block, which can directly drive the liquid crystal display. By manually adjusting R ₁₀ to make U′=U _i , at this time, the two LEDs D ₃ and D ₄ are not emitting light, so that the test value of the day can be stored, and the second measurement can be intuitively displayed according to the state of the LED. Determine the difference from yesterday's value. Since the electronic components in the circuit have certain requirements for the voltage, the circuit will produce distortion when it is lower than the specified value, so the power supply setting has an alarm function.

Using this test instrument to do some practical test research, and achieved obvious results, the results are as follows:

1. Experiments in medicine:

From September 9th to September 30th, 1988, we conducted conductivity tests on the urine of more than 300 patients in the PLA 117 Hospital of the Nanjing Military Region. The urine collected in this experiment is morning urine, and we have adopted the following dilution method for each sample: urine: deionized water = 1me: 8me. The container and electrodes were rinsed with deionized water after each measurement.

Of all 300 samples, 28 were from normal subjects, which were used as standard urine for comparison. In addition, 75% of the hospitalized patients are patients in orthopedics, ENT and other departments. Their urine composition is generally not affected by the disease and can be regarded as normal. Thus, there are two sets of normal urine conductivity values: normal values in physical examination and normal values in patients. Their urine conductivity measurements are as follows: Normal examiners: 28 people. The conductivity range is:

0.710～2.346mv/cm, K=1.574mv/cm, S=0.4079mv/cm. Normal value among patients: 75 cases. The conductivity range is: 0.783～2.029mv/cm, K=1.3238mv/cm, S=0.3227mv/cm.

According to the range of normal urine conductance value, we take 1.000mv/cm as the lower limit of normal value and 2.000mv/cm as the upper limit. If it exceeds this limit, it is too low or too high, which is an abnormal value. Observing all the cases, we found that there were 7 cases of high samples, as shown in Table 1.

There were 69 cases with low conductivity, among which there were 11 cases of nephropathy, 6 cases of hematuria, 7 cases of liver disease, and 5 cases of gallbladder disease. The results are listed in Table 2, Table 3, Table 4 and Table 5 respectively.

2. Experiments in natural contraception:

We identified a female college student and conducted in vivo measurements of oral saliva for more than a month. The changes in the measured saliva conductivity during the menstrual cycle of women are shown in Figure 7.

The above curves are measured from the 3rd day of menstruation. A clear peak appeared on the 9th day. According to the calculation of the physiological ovulation law, the subject's ovulation period will occur on the 14th or 15th day. Based on this comparison with the graph, it can be seen that the electrical conductivity of the young woman's saliva had an obvious peak value from the 5th day to the 6th day before ovulation.

From this, it can be preliminarily considered that by testing the conductivity of saliva in the oral cavity of young women in Yuling, it is possible to find a convenient natural contraceptive method to replace the drug contraceptive method that brings pain and sequelae to the majority of women in Yuling. Open up a brand new path for family planning in the world.

3. Experiments on the composition of oral saliva:

We selected five healthy college students (2 males and 3 females) with an average age of 22 to determine the changes in the composition of saliva in their oral cavity before and after eating. Measurements are taken every minute or about 10 minutes after a meal. The average data of its 5 people are shown in Table 6. It can be seen that the resistivity of saliva after a meal is significantly increased compared with that before a meal, which clearly shows that before and after eating, the inorganic ion components in saliva change from more to less, and the organic components change from more to less. A state of change from less to more.

From the above experimental research, it can be shown that this test instrument can quickly obtain test results without using test paper and microscope, without causing injury, toxicity, or disease, and has multifunctional utility, which can measure human urine, saliva, blood, etc. Various physiological parameters in body fluids. It can be used as a general survey of diseases in medicine, and can be used for early diagnosis of certain diseases such as kidney disease, liver disease, gallbladder disease, etc. For research, it can measure blood flow, which can be used as the basis for accurate and simple control during blood transfusion of surgical patients, can measure hemoglobin content, monitor the gas metabolism status of patients, and so on. It is a portable test instrument that can be used by various medical departments, families, medical schools, and research institutions.

Table 6

Claims (3)

1. A human body fluid parameter tester, which is characterized by a self-signal generator, conductivity cell, signal processing, storage comparison, output display, regulated power supply, and voltage loss alarm. The pulse wave is output from the pulse source NE555, After being delayed by the R ₄ C ₂ parallel network, it is input to the input terminal of the inverter composed of NAND gates to output the lagging reverse pulse wave with the same width, and then input the pulse wave and reverse pulse wave into the adder A ₂ After superposition and shaping, the symmetrical positive and negative voltage bidirectional pulse waves are output to the conductivity cell to obtain the current value, which is converted into a voltage value by the operational amplifier _A3 and input to the signal input terminal of the sample holder LF398, and the pulse signal from the inverter is passed through A ₄ Output to R ₁₉ C ₃ series circuit for integration and then connected to A ₉ When U _C3 rises to the opening threshold voltage of A ₉ , a positive pulse is output from A ₃ to the sampling signal input terminal of the sample holder to make the signal input terminal The received signal is sampled, and the sampling signal disappears synchronously with the disappearance of the negative pulse signal and enters the holding period until the next sampling pulse is generated. The signal output from the sample holder is sent to the CC7016 integrated block to directly drive the liquid crystal display. 2. The tester according to claim 1, characterized in that the conductivity cell is composed of the measured body fluid and electrodes, the electrodes are box-shaped, the box seat is made of plexiglass material used in dentistry, and two stainless steel needles are inserted into the box There is a groove on one side of the box seat, so that the ends of the two stainless steel needles are exposed in the groove to form a double electrode. 3. The tester according to claim 1, characterized in that there is a storage circuit, and the test value of the current day is compared with the test value of the next day through light-emitting diodes.

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