Urease Biosensor And Testing Systems

Urea has universal existed in processing of Alcoholic fermentation.It can generate Ethyl carbonate by the reaction of urea and ethanol,which is carcinogenic and harmful to human health.A variety of detection methods included analysis method of enzyme electrode,liquid chromatography and chemiluminescence has been applied.Existing measurement methods require complex test methods,procedures and equipment,what is more,it is operated complicatedly,slowly and difficultly.Therefore,it is very necessary to design a system for the rapid detection of urea and to control the quality and safety of food.This paper describes the origin,background and present foreign and domestic research to urea content.Besides it introduces common detection methods to urea,enzymatic curing technology,and the works of enzyme electrode etc.The standard curve has been drawn.the shortcomings to existing measuring instruments,the system to urea rapid detection designs with urease biosensor,reaction tank,hardware circuit and software program.The ammonium ion selective electrode is used to assemble biosensor,the head of which is covered by sensing membrane of urease.The reaction tank is designed based on the principle of urease biosensor.Meanwhile,the standard urea solutions in different concentrations were measured by biosensor to detect a standard curve.The system is based on Msp430 microcontroller development board,module of LCD12864,amplifier Module with LM358 and Industrial temperature sensors with DS18B20.The system software program is formed by sub-module program.In addition,debugging movement is accomplished.System contains measurement function and calibration function.Measurement function is to measure urea content.When the system is used for the first or not used for a long time,properties of these urease membranes are not the same.So calibration function is used to correct for the standard curve.Besides,the accuracy is analyzed though repeatedly measuring standard solution many times.The maximum relative standard deviation is 1.086%.The steps of recovery experiments are to add urea solutions in five different concentrations to urea solution in 20 mg / L.Recoveries is greater than 80%.Uncertainty Analysis in precision Measurement is also completed.Synthesis of uncertainty is 0.587 mg / L and expanded uncertainty is 1.439 mg / L.The system can be used to detect urea content quickly,and it includes characteristics of Stable performance,high precision and Simple operation.It can measure anywhere because of portable design.Trial production and commissioning is also completed,which provide a reliable basis to the design of portable urea rapid detection instrument.