Study On AlGaN/GaN HEMT Heavy Metal Ion Sensor For Trace Detection

The main source of heavy metals is usually from human activities such as industrial processes,agriculture and mining.Because microorganisms are unable to degrade heavy metals,heavy metals are released into aquatic and terrestrial systems,further transferred to life systems including plants,animals and humans,and accumulate through transfer.Heavy metal ions such as cobalt,copper,iron,manganese and zinc play an important role in biological organisms.For the maintenance of metabolism,trace amounts can satisfy the normal functions in living organisms.However,excessive levels or even small doses of highly toxic metals(ie,lead,cadmium,mercury,arsenic,antimony,etc.)can cause serious problems for the environment and human health.The accumulation of these metals in the human body can cause diseases of the central nervous system,liver and kidneys,skin,bones and teeth.Therefore,the detection of heavy metals in the environment and in the human body has great practical significance.Due to the unique closed shell structure of zinc ions,there is no oxidative activity in the biological environment,making it difficult for the sensor to detect in the free state.In recent years,the fluorescence detection method has exhibited good performance characteristics in various fields,especially in the detection of heavy metal ions,and has excellent advantages in detection,low detection cost and visible detection results,and is widely used for heavy metal ion transmission.The research of sensation,but due to the limitations of its response time and sensitivity,it still can not meet the practical needs of zinc ion sensors for rapid trace detection.In this paper,a Schiff base fluorescence-detected zinc ion method was used to design a Schiff base functionalized AlGaN/GaN HEMT zinc ion sensor based on AlGaN/GaN HEMT biosensor.The specific research work is as follows:(1)The background and traditional methods of zinc ion detection are described,and combined with AlGaN/GaN HEMT biochemical sensors,it exhibits good chemical stability in liquid detection environment,and exhibits excellent sensitivity and detection limit in ion detection.A concept of an AlGaN/GaN HEMT zinc ion sensor with extended gate structure for trace detection is proposed.(2)Analyze the detection mechanism of the extended-gate structure AlGaN/GaN HEMT zinc ion sensor for trace detection,and perform micro-nano processing such as pre-processing,mesa etching,ohmic contact,lead electrode,extended gate electrode and back-end process.Fabrication of an extended-grating AlGaN/GaN HEMT zinc ion sensor was completed.(3)In the Schiff base fluorescence detection method,the Schiff base formed by the combination of bovine serum albumin and salicylaldehyde has good specificity for zinc ions.We express the trace amount of AlGaN/GaN HEMT zinc ion sensor.The modification was studied and experimentally,and the modification method of mercaptoethylamine was proposed,and then modified to 11-decylundecanoic acid modification method.After modification of 11-mercaptoundecanoic acid on the surface of the extended gate,the activation was successful in the extended gate.The surface was fixed with bovine serum albumin and the salicylaldehyde was modified to form a specific Schiff base,and the surface modification of the trace amount of AlGaN/GaN HEMT zinc ion sensor was completed.(4)The surface potential change on the extended gate is caused by the complex reaction between the Schiff base and the zinc ion,and the source leakage current is finally changed to achieve the purpose of detecting the zinc ion.The Schiff base functionalized extended-gate AlGaN/GaN HEMT ion sensor exhibits a fast response(less than 10 seconds)for zinc ions and a detection limit(LOD)of 1 fM.At the same time,the detection method showed good specificity and stability during real-time detection in the range of 1 fM to 1μM(R~2=0.9963)zinc ion concentration.Studies in this paper have shown that Schiff base functionalized traces formed by the reaction of bovine serum albumin and salicylaldehyde exhibit excellent properties in zinc ion detection with extended-gate AlGaN/GaN HEMT sensors,which are trace amounts of zinc ions.Real-time detection provides a detection method with broad application prospects.