| Clotting time examination is a test for patients before undergoing surgery,so that doctors can be unaware of their own coagulation function and prevent massive bleeding in operation.At present,there are many different brands,different properties of clotting time detection instrument in market,but there is no clotting time detection instruments which are really suitable for the rural demand,small,mobile,low cost detection instrument with high precision.The purpose of this study is to design a small and mobile clotting time detection system suitable for rural health care,maternal and child health care and family planning services.A clotting time detection system based on STC89C52 RD microcontroller is proposed.High brightness LEDs with a wavelength of 470 nm and a diameter of 5mm is used as the detection light source.In order to eliminate the interference of current to LED's brightness,an adjustable precision constant current source is designed to supply power to LEDs.Using the method of scattering immunoturbidimetric assay,to avoid turbidimetry-immunoassay's shortcomings that cannot overcome jaundice,hemolysis,hyperlipidemia.It has a silicon photocell with low power consumption,low noise,high stability,sensitive response and so on as a photoelectric sensor.The MCU circuit,display circuit,keyboard circuit,print circuit,storage circuit,serial interface circuit,power supply circuit and connection between MCU and each circuit are described in detail.In order to achieve removable design,two schemes of 220 V AC power supply and automotive battery power supply are provided,and a low-power thermal printer is built to facilitate printing of inspection reports.A set of constant temperature system is built to ensure the plasma temperature to be kept in the normal temperature range of human body.The composition of the constant temperature system and the connection with the microcomputer are briefly described.The system uses a high speed optical dynamic software for scanning.An uninterrupted scan is performed from the beginning of the clotting reaction to the end of the clotting reaction.The scattering intensity of each moment is drawn into a detection curve.The linear region of the change of optical density at the moment of clotting is found by modern microcomputer processing technology,and get the results of detection.The effect of different levels of turbidity in plasma before coagulation reaction was avoided,and the detection precision is improved.The program diagram of displaying subroutines,printing subroutines and keypad subroutines is described.The domination principle and calculation program of the PID algorithm used in the constant temperature system are introduced in detail.According to the requirements of clotting time detection system,we have designed the circuit schematic diagram and the circuit board diagram,welding the PCB on the basis of the printed circuit board.We have compiled a software program,and the simulation of hardware and software were carried out by Wei Fu series E6000/s simulator.Finally,the parts are combined to be debugged and the program chips are solidified to run.The results of simulation operation and chip operation show that the scheme of portable multifunctional clotting time detection system is feasible,the algorithm is reliable,and it has certain medical application value. |
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