A liquid level detection system and method for medical instruments

Abstract

The invention provides a liquid level detection system for medical instruments, which is used to solve the problem of inaccurate sample needle sampling in the prior art, excessive sampling of unnecessary liquid by the sample needle, resulting in cross-contamination. The system includes: an excitation source, which excites the sample needle to generate an induced charge; a sample needle, which is used to absorb the measured liquid and output its own induced charge; an acquisition circuit, which collects the induced charge output by the sample needle in real time and converts it into a corresponding induced charge analog signal; AD sampling circuit, which converts the analog signal of the induced charge into a digital signal of the induced charge; MPU circuit, which is used to compare the digital signal of the induced charge with the preset non-contact digital signal, and confirm whether the sample needle is in contact with the liquid surface; digital output circuit for outputting confirmation results. The invention can accurately confirm that the sample needle touches the liquid surface, thereby controlling the liquid suction stroke of the sample needle and ensuring that the liquid sucked by the sample needle is the preset sampling liquid.

Description

technical field [0001] The invention relates to the field of medical equipment auxiliary equipment, in particular to a liquid level detection system and method of a medical equipment. Background technique [0002] When analyzing body fluids, automatic biochemical analyzers and immune analyzers in medical testing need to take samples first. During the sampling process, the liquid-absorbing sample needle is driven by the motor and goes down in the sample test tube. When it touches the liquid surface, in order to prevent Inserting the sample needle too deeply will increase the difficulty of cleaning. If the cleaning is not clean, it will cause cross-contamination, so the motor must be stopped. After the sample needle absorbs the body fluid, it will go up and return under the drive of the motor. The liquid level detection is carried out first, that is, when the sample needle touches the liquid level, it is necessary to output a contact liquid level signal to the motor to control...

AI Technical Summary

Problems solved by technology

[0003] In the prior art, the commonly used liquid level detection adopts a capacitive liquid level detection circuit, such as figure 1 As shown, the circuit is composed of oscillation and frequency division circuit, phase-locked loop, low-pass filter, high-pass filter, amplification, AD conversion, CPU processing and other parts. figure 1 The method shown adopts the conventional probe capacitance detection method. Since it is not convenient to directly measure the probe capacitance and its variation in engineering, the circuit in the prior art usually converts the capacitance into a voltage, and then converts it through AD However, the above-mentioned circuit design costs are high, the adjustment is cumbersome, the reliability is low, the circuit structure is complex, and the scalability is poor. The voltage control in the phase-locked loop The oscillator adopts RC type, its anti-interference ability is low, so the detection accuracy is low

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