Development On Offline Compositive Bio-artificial Liver Therapy Device

Artificial liver device is an essential equipment in the clinical treatment of hepatic failure.Itsclinical application has many disadvantages,such as the higher equipment cost as importation, theexpensive consumption material, the changeless treatment process etc,which result in higherequipment and long-term use cost, and increasing economical burden of patient.The offlinecompositive bio-artificial liver, is the innovation of clinical application of artificial liver treatmenttechnology. The existing artificial liver treatment equipment almost focuses on the single functionand its application, lacks in multiple functions combination in one device.These problems resultin (1) insufficient power support;(2) lack of biology reaction environment;(3) the control systemand treatment process can not meet the demands of offline clinical application of bio-artificialliver device.This paper focuses on the requirements of offline bio-artificial liver treatment, resolves theshortcomings of the existing biological artificial liver treatment equipment, and design aninnovative offline compositive bio-artificial liver to be used in clinical blood purificationtreatment and experimental research. The main research works is as follows,which includesresearch contents, methods, and results.(1) The construction of offline compositive bio-artificial liver treatment processConstruction of the offline compositive bio-artificial liver treatment process is based on theexisting treatment method and process. Normally, artificial liver therapy method is chiefly dividedinto two kinds:non-biological and biological treatment,and most existing treatment devices belongto non-biological treatment,or biological treatment which has single function. At present,few ofbio-reactor treatment,but segmented treatment,or several machines corporation is usually adoptedin clinical therapy.The offline compositive bio-artificial liver device is coupled single bio-reaction withnon-bio-reaction treatment.So-called “offline” is the means that the patient is isolated withextracorporeal circulation equipment physically to avoid the influence of pressure,velocity onpatient.After plasmapheresis and adsorption treatment, as the amount of exoteric accumulatedplasma is achieved the preset value, the plasma perfusion and bio-reaction treatment areproceed,and then the purified plasma is transfused back to the patient.The offline compositive treatment process assures the indirect connection between patient withon line plasma purification process,namely,molecular adsorption and bio-reaction treatmentprocess are isolated with patient, so it is called the offline compositive bio-artificial liver. Duringthe extracorporeal circulation treatment, the physical effects caused by offline therapy, such as thechange of temperature, flow, pressure, have little influence on patient.It brings many advantages,such as higher security and stability,and lesser treatment time, physical comfort.(2) The development of control system for offline compositive bio-artificial liver therapydeviceThe control system of offline compositive bio-artificial liver is consists of programmablecontroller (PLC), touch screen man-machine interface, pressure sensor, weighing sensor, hallsensors, clip pipe valve and so on. It can provide many kinds of treatment mode,and accomplishthe automatic treatment process.The control system provides driving force for extracorporealcirculation of patients,heating and temperature control,plasma mass of in and out patientbalance,purification and disinfection environment for bio-reactor treatment,operation parametersmodification during treatment, safety monitoring and alarming,etc,which has manyadvantages,such as friendly man-machine interface,higher safety and stability,multiple optionaltreatment mode,indication the approach of tube coupling on touch screen, operational andalarming parameters setting,etc.All paremetes are displayed on the touch screen,at the same time,are compared with the set values to decide whether compensation or alarming.(3) The design of incubator chamber, air purification and video monitoring deviceBecause the bio-reactor is placed in incubator chamber, which should maintain the environmentsterile, constant temperature, real-time visual during treatment. incubator chamber is consists ofbox, air purification device, ultraviolet disinfection lamp, carbon fiber heater, video monitor,bioreactor rocker. Carbon fiber wires is used as heating materials,which is supplied by24v lowvoltage power,and the temperature of incubator chamber can be controlled in the range of34to40℃. Infrared night vision camera is placed in the incubator chamber to monitor its real-timestatus. At the top of incubator chamber,there is a mouth for the air circulation purification, at thesame time,which is used for the air cycle to balance the temperature. A ultraviolet disinfectionlamp is placed in the incubator chamber to disinfect the internal surface during preheating.(4) The design and manufacture of mechanical structure.The mechanical struture of bio-artificial liver device is simulated repeatedly by3D drawingsoftware to gain more better result.All machine parts are made by precision CNC machine tool,and the prototype artificial liver treatment equipment is developed. Filter clamp is designed forfour adjustable direction to meet the demands of different angles when dialyser and pipe areinstalled. According to the requirements of treatment, all tube must be placed in the incubatorchamber.(5) The design and manufacture of adjustable peristaltic pumpPeristaltic pump is composed of servo motor,pump head and base, which is driven by PLC tocontrol and adjust the rotation speed. producing the extracorporeal circulation power for bloodpurification. Pump head consists of is pump head body, roller, roller frame, anti-shedplug,connecting shaft,and is produced by precision machine tool.The pedestal consists of pumpcranium, base body.Hall switch sensor is installed on the Peristaltic pump to ensure the operationsafety. The clamp size of Peristaltic pump is adjustable to adapt for the demands of differentmaterials, tube size, and expand the pump head adaptability. (6) Security alarm functionSecurity alarm function is mainly used to remind the operator by sound and light alarm whenall kinds of malfunction emergence. The alarm instances include:(1)the temperature in incubatorchamber or heater is higher or lower than preset value, at the same timen,the temperature result isalso as an input parameter to adjust the output heating amount, the system can be timely andeffective to adjust heating system of automatic balance;(2) the bubbles detection. During theoperation process, the different sizes of bubble are simulated to test the sensitivity of sensor andthe real-time response of alarm device. The testing result shows that the alarm system can respondto different bubbles,including minuteness bubbles in the tube,meanwhile the pipeline valve isclosed to terminate the blood circulation;(3) blood leak detection. During the operation process,the simulation of different concentration of the different liquid color is simulated to test thesensitivity of blood leak detection.The testing result shows that the alarm system can respond todifferent liquid color in the tube,meanwhile the pipeline valve is closed to terminate the bloodcirculation.(4) electronic weighing balance detection. According the preset parameter of bloodbalance weighting, the testing result shows that the system can respond to the out of rangeweight,at the same time,the real-time weight is adjusted by pump speed controlling.In conclusion, the advantages of offline compositive biological artificial liver in this paperinclude:(1) Three treatment modes, plasma exchange, adsorption treatment, and bio-artificialliver treatment are integrated in one device,and on the base of treatment demands,three treatmentmodes are optional.By offline process design, patients can be isolated from blood purificationprocess,and the patient’s physiological reaction is decreased,the demanded volume of blood andtime consuming are both reduced;(2) intelligent control: the process operation is automatedcontrolled by PLC and its peripheral modules, the touch screen is as man-machine interface,whichdisplays clearly all real-time treatment process,and easy to operate.The alarm response during thetreatment process is rapid and accurate;(3) higher safety. The device is equipped with videomonitoring, alarm device, a variety of sensors, low voltage power supply for heater,isolationtransformer, offline treatment process,all of these provide more security for patient;(4) Incubatorchamber,pipeline,bio-reactor and plasma pool are integrated in one set, and the its cleanliness isimproved evidently;(5)The operation of treatment process is convenient, and hardware composedby several modules is easy to be maintained and extended.