Research On The Automatic Testing System For The Quality Of The Hydrocephalus Shunts

We often use the equipments that commonly used in laboratory for the detection that the quality of the disposable hydrocephalus shunts.These equipments are esay obtain and low costing.But when they are compared to the foreign's automation equipment,they will be so simple,weaken stability,poor precision and low efficiency.At the same time,the abroad's also have some shortcomings,for example,high manufacturing cost,large volume,process dispersion etc..The principle of testing the quality of shunt is simple,but there are some technical difficulties in the actual operation,such as micro pressure difficult to detect and micro flow difficult to control.To overcome the mentioned disadvantages,especially in the place that the micro pressure difficult to accurately detect,and micro flow difficult to accurately control,focuing on the technical difficulties to research and overcome.In the aspect of the micro pressure detection,the pressure transmitter is the first time used to detect the weak hydraulic pressure.This measure has a great change in the place that detection of hydraulic pressure of the shunt.A sensor made by using the weak elastic sensitive piezoelectric materials under the pressure can generated the deformation of the charge,then through amplifying and shaping circuit will output voltage shandard.and the data acquisition,and then combine with data acquisition card and computer to analog digital conversion,at last,determinating of the measured pressure value.In the aspect of micro flow control,peristaltic pump is used as flow control device.It is congtrbute to the peristaltic pump's working principle that extrusion the hose to product the deformation,after leading to the vacuum,the experimental liquid can be pump.The peristaltic pump has a lot of advantages.For example,it can not only make micro flow effectively transport but also avoid the fluid pollute due to the transmission process untouch to the pump body.So it can satisfy the require that controlling the micro flowing in the shut quality detecting.Furthermore,it can avoid the blocking because of the pulltion experimental liquid.In addition,In additon,the mode that a pump is used to drive a multi-channel can realize multiple groups of shunts detecting mission in a same time,so as to to improve the work efficiency.In this project,four experimental items were designed for the quality testing of hydrocephalus shunts.The opening and closing pressure testing item is mainly to explore the opening pressure and closing pressure of the shunt.By using the principle of communicating vessels,we can connect the shunt,presssure sensor and manometer.Through the combination,the observer can read the pressure data from the manometer also can read the screen at the same time.Flow-pressure characteristic item is to reasch the vray pressure of the shunt valve at different flow rates.By adustabling the speed of peristaltic pump to obtain different drawing,and the computer be combined with sensor to control pressure data acquisition.At the same time,the testing software will automatic draw of the pressure curve,seeing the relationship between the data more vivid and intuitive.The back-flow characteristic is aiming to verify the capacity of closeing the valve blocking the reversing flowing.By reversing installation of the shunt and adjusting the peristaltic pump's speed in different flowing rate,testing leakage flow rates at the end of shunt.The goal of long-term stability test is to verify the resist fatigue.The equipment uses IPC one advantage is it can run 28 days no stopping the work that data acquisition.The testing software made for the equipment can acquisition the data we need and drawing figures based on the data.After completing the whole mission that assembling the equipments,we should test and debugging the actual performance,then correcting the pressure sensor and peristaltic pump respectively,establishing mathematical models for sensor and peristaltic pump.These measures can control the sensor detects accuracy and the pump speed exactly.The result of testing opening and closing pressure function module is proved that this function module meets the missing that opening and closing the pressure data acquisition,and generats the report and prints.The flow-pressure function module test result that the system can control the peristaltic pump and sensor coordination work to measure the resistance force of the shunt under different flow rates.The experimental result for reflux characteristic function module is tested that this module realizes higher precision measure in micro flow.The testing for long-term stability founction module,the result turn out that this founction module can complete the data acquisition working stable achieve 28 days.The design scheme that the all-in-one machine can effectively decrease the repeated wast time due to the current shunt detecting process dispersion,and decrease the volume needing.Finally,testing for the equipment and the result proves that the equipment can accurate,stable,automatic do all the mission that detecting the quality of shunt.The test result shows that the design has achived the expected research and development goals.