第3节电容式输液液位传感器理论设计-read.doc

摘 要：目前由于没有有效、经济的自动检测装置，在输液时病人需要专人监护，加重了病人的思想负担和护理人员的劳动负担，也不利于病区的综合管理，为此我们研制了医用输液液位和输液速度实时检测系统。 本系统的特点：自动检测输液液位，并能将各床位液位和输液速度信号传送至护办室，在护办室对多个病房各个床位的输液情况进行巡回检测和显示。当液位低于设定下限值，输液速度过高或过低，在护办室和相应床位处发出声光报警，提醒护理人员及时处理，采用一种变介电常数型电容式液位传感器。通过对不同宽度电极下传感器电容与对应液位的分析，发现液位处于输液瓶上部圆柱段时电容与液位高度之间有很好的线性关系，而在下部呈现非线性;传感器灵敏度随电极宽度的增加而近似线性提高。同时发现传感器灵敏度与液位下降速度相关。进而建立了传感器数学模型，分析影响传感器灵敏度的因素和机理。 本装置硬件部分为电容式传感器，其结构简单，适应性强，固有频率高，动态响应时间短，软件部分用单片机实现，实现多路信号采集处理、参数设置、异常报警和报警取消，总线通信等。 关键词：静脉输液，液位检测，电容式传感器，电极，极化 Abstract: Because of the absence of the automatically measuring settings, special medical person has to ward them. This aggravates the patients mental burden and the nursing persons working burden. This also handicaps the synthesis management of the ward. The system is developed to measure infusion liquid level and infusion speed. The system automatically transports the detecting signal to the nursing office. In it the infusing situation of every bed in every sickroom is displayed. When the infusion liquid level is under the given lower limit and the infusion speed is much faster or lower, the alarm will be made in nursing office and corresponding bed to remind the paramedic to deal with it, a variable- dielectric-constant capacitive sensor is designed. The experimental data is obtained with the use of electrodes of different width. By analyzing the correlation between them, it is found that the sensitivity affected by the speed of infusion. The model of the sensor is presented and then the affecting factors and the mechanism on the sensitivity are discussed. The hardware device part of the capacitive sensor, its simple structure, strong adaptability and high natural frequency, dynamic response time is short. software with MCU, multi-channel signal acquisition and processing, parameter setting, unusual warning and alarm canceled, Bus communications and so on. Keywords: vein infusion, liquid level measuring, capacitive sensor, electrode, polarization 第1章 绪 论 第1.1节 课题背景 随着微电子技术和信息技术的发展和应用，医疗设