This paper introduces a 96-channel high-speed anticoagulant drug screening platform based on the transmission turbidity method and the single-chip 89C52. The instrument automatically completes the real-time detection and data acquisition of blood (plasma) clotting time, and the accuracy, speed and sensitivity of data acquisition are greatly improved compared with the traditional clotting time measuring instrument. A new approach to the measurement of clotting time for the screening of related drugs has been proposed. The process of blood coagulation is very complicated. In a normal physiological state, the blood coagulation system and the anticoagulant system are in a state of self-regulation. If this balance is destroyed, a coagulation system disease is formed. The most commonly used anticoagulant drug in the clinic is heparin. Although this drug has a good anticoagulant effect, it is accompanied by side effects such as blood and thrombocytopenia, and when the patient has diffuse intravascular coagulation, etc. It can't be used when the disease is over. The use of existing oral anticoagulant drugs (such as acetone coumarin [1]) is not satisfactory. Therefore, the development of new anticoagulant drugs is very necessary. The first step in the development of anticoagulant drugs is to test the anticoagulant effect of the drug, which is the detection of clotting time. There are currently two commonly accepted indicators for measuring clotting time: Prothrombin TIme (PT) and Activated Partial Thromboplas TIn Time (APTT). These two indicators are The distribution was developed by the International Committee for Standardization of Hematology (ICSH), the Estimated Blood and Hemostasis Committee (ICTH), and the American Committee for Clinical Laboratory Standards (NCCLS) [2]. PT and APTT can not only replace the traditional Duke method bleeding time and slide clotting time as a new clinical hemostatic function index, but also provide better monitoring indicators for anticoagulant drug development process. The normal blood coagulation process is very short, and even if an anticoagulant is added, it will not exceed 1 minute. Under normal circumstances, the PT will not exceed 20 seconds, which brings great difficulties to manual measurement. In order to find a convenient detection method, many companies at home and abroad have begun to develop related automated clotting time measuring instruments, and have already invested Put the market such as TECO's TEChrom IV plus 4-channel semi-automatic thrombus/hemostatic tester from Germany TECO; STAGO automatic thrombus/hemostatic analyzer from BIOCHEM, France. Although these coagulation measuring instruments can complete the simultaneous detection of one or several samples, they still use the routine test routine, the detection speed is limited, the sample dosage is relatively large, the sample wave is mostly fixed on the instrument, the cleaning is inconvenient, and the price is also quite expensive. Not suitable for drug development. In order to improve the performance of the coagulation measuring instrument and meet the demand of high-throughput drug screening, we have designed a new set of automatic clotting time detectors using single-chip microcomputers, aiming at facilitating the quality control of new drug development. This small clotting time measuring device (only 30cm×20cm×12cm) can not only perform 96-channel parallel real-time detection, but also has a small sample amount (20μl) and high sensitivity (0.1 second), which has a good application prospect. The coagulation of blood is physically a process of insoluble fibrin formation, and the amount of non-soluble fibrin increases abruptly in a short period of time. In this way, the light transmission rate of the whole blood is rapidly reduced (the turbidity is increased), and gradually becomes slower after a certain period of time. Usually, the clotting time we measured refers to the initial stage of the formation of non-soluble fibrin, that is, the time when the turbidity changes to three times the bathing ratio. The nephelometry method is designed using the principle that blood has a sudden increase in turbidity during coagulation. As long as the detection device has sufficient sensitivity, the time of blood coagulation can be detected. The detector adopts a standard flat-bottom transparent 96-well plate as a sample cell, and the upper and lower sides are respectively a one-to-one photodiode and a light-emitting diode, and the sample cell adopts a drawer structure. Each time you use it, you can pull out the drawer, put it on a 96-well plate, add coagulation reagent and blood (plasma), then start the detection switch and start data collection. Since the amount of voltage signal received through the photodiode tends to be relatively low (several mV), it is critical to the choice of source hand detection device. Therefore, before the instrument design, firstly, several different light-emitting diodes (hereinafter referred to as LEDs) and their corresponding photodiodes were selected to calculate the corresponding transmittance of the coagulation process. Figure 1 shows the basic circuit of a photodiode. The current across the diode is: Where I is the current through the non-sensitive diode, Is is the reverse saturation current, VD is the voltage across the diode, VT=kT/q is called the mixture for the equivalent, where k is the Boltzmann constant and T is the thermodynamics Temperature, q is the amount of electricity. At 300K, VT ≈ 26mV. In the reverse bias, as long as |VD| is more than several times larger than VT, I=-Is, where the negative sign represents the reverse current. Experiments have shown that the reverse current of the photodiode is proportional to the loading voltage on the LED within a certain range, as shown in Figure 2. This is because during the normal illumination of the LED, there is a proportional relationship between the LED loading voltage and the output light intensity; the reverse current of the photodiode is also proportional to its absorbed light intensity. Based on this we can make the following inference: Assuming that the absorbed light intensity through the photodiode is φ, then I=-Is=Cφ+m≈Cφ Wherein C and m are factors which vary only with temperature, m ≈ 0. The voltage across the resistor R in series with the photodiode is V=IR=CφR, and is: φ=φ0+Δφ, V=V0+ΔV, V0=CRφ0, ΔV=CRΔφ. Among them, V0 and φ0 are the voltages across the R resistance and the absorption light of the photodiode before the start of the coagulation reaction. Terminal Wires,Black Tinned Copper Terminal Wires,Bare Copper Terminal Wires,Tinned Copper Terminal Wires Dongguan ZhiChuangXing Electronics Co., LTD , https://www.zcxelectronics.com
