高压灭菌器无线温度压力记录仪的设计

Design of wireless temperature and pressure recorder for steam autoclave

高压灭菌器作为医疗卫生、食品药品等行业的重要灭菌设备,需要定期进行温度和压力校准。文中采用耐高温冲击的电路系统,设计了一种投入式、具备防水功能的无线温度压力记录仪,可根据需要任意放置在设备中完成校准任务。硬件电路采用恒流源激励的四线制铂电阻测温电路、具有温度补偿和偏移校正的压力测量电路,结合高精度模数转换芯片ADS1148完成温度和压力测量。为了提高测温精度,对温度数据采用最小二乘法分段拟合;为消除硅压阻式压力传感器的零点和灵敏度漂移的影响,采用结合曲线拟合和三次样条插值的温度补偿算法,使压力传感器线性输出较好。该记录仪体积小巧、内置大容量耐高温锂电池,可在0~150℃环境中长时间稳定工作。实验结果表明,记录仪温度测量误差小于0.05℃,压力测量误差小于0.14%FS。

As an important sterilization equipment in medical and health,food and drug industries,steam autoclaves needs regular temperature and pressure calibration.In this paper,a wireless temperature and pressure recorder with water⁃proof function is designed based on the circuit system with high⁃temperature shock resistance.It can be placed in the equipment at will to complete the calibration task.The hardware circuit adopts four wire platinum resistance temperature measurement circuit excited by constant current source,pressure measurement circuit with temperature compensation and offset correction,and high⁃precision analog⁃to⁃digital conversion chip ADS1148 to complete temperature and pressure measurement.In order to improve the accuracy of temperature measurement,the least square method is used to fit the temperature data in sections;in order to eliminate the influence of zero point and sensitivity drift of silicon piezoresistive pressure sensor,a temperature compensation algorithm combining curve fitting and cubic spline interpolation is proposed to make the pressure sensor have good linear output.The recorder is small in size,built⁃in high⁃temperature lithium battery,and can work stably in 0~150℃environment for a long time.The experimental results show that the temperature measurement error is less than 0.05℃and the pressure measurement error is less than 0.14%FS.