The Study Of GaN Based Sensor Which Was Used To Detecte Harm Anion In Drinking Water

Water is the source of life, almost all animals and plants can't live on the earth without water. As populations grow, the resource of water is reducing day by day, and all kinds of toxicants and hazardous substances run into the ground?rivers?lakes and reservoir, which make the ground water and surface water polluted seriously with the development of industry and agriculture technology. Although city water also need disinfected treatment, the processing of disinfection does not remove heavy metal ions, and it will be bring some harmful disinfection by-products such as halogenated actic acid?bromate?chlorate anions etc., they have been proven to be of getetictoxicity? carcinogenic or reproductive and developmental toxicities. In this context, we make the advantages of the ion imprinted polymer combined with GaN HEMT device to construct electrochemical sensors, realizing detection of phosphate?trichloroacetic acid harmful anions.The character of sensors are strong ion selectivity?high sensitivity?low detection limit?detection stable and can be used repeatedly. The main research contents and results of this paper are as follows:1. Based on the characteristics of the phosphate anion imprinted polymer and AlGaN/GaN HEMT device, a novel electrochemical sensor for detection of phosphate anion was designed. The characteristics of the AlGaN/GaN HEMT sensor were detected by Keithley 2600A, and the experimental results showed that the sensor is of high selectivity for phosphate anion solutions, but it can hardly recognize permanganate and sulfate etc interfering ions. This is because the ion imprinted polymer has specific recognition to the template ion. And the sensitive of the sensor is 3.191 ?A/mg·L-1, the detection limit is 1.97?g/L. The sensor showed high selectivity sensitivity and stability for phosphate anion, so it has great application potential on line monitoring field of phosphate anion.2. Due to AlInN/GaN heterojunction with thinner barrier layer, and the surface charge is more sensitive to regulate the concentration of two dimensional electron gas, an ultrasensitive electrochemical sensor for phosphate anion was designed. The performance of the sensor was tested using the Keithley 2600A Source Meter. We compared the test results with AlGaN/GaN HEMT sensor, it was found that the AlInN/GaN HEMT sensor had higher selection and identification of phosphate anion, stronger anti-interference ability. This is mainly because AlInN/GaN heterojunction barrier layer is thinner, the distance is short between surface charge and 2DEG channel, which makes control the concentration of 2DEG easily. The the sensitivity is 3.191 ?A/mg·L-1 for the AlGaN/GaN HEMT sensor, and 60.831?A/mg·L-1 for the AlInN/GaN HEMT sensor. Their detection limited is 1.97?g/L?0.09?g/L, respectively. So AlInN/GaN HEMT sensor with thinner barrier is more sensitive than AlGaN/GaN HEMT sensor, it has potential application advatages in the ion sensors.3. Using novel surface imprinting technique, the ungated of AlInN/GaN HEMT device was modified by trichloroacetic acid ion imprinted polymers which were preparated by changing the template ion and functional monomer, the new sensor for detection of trichloroacetic acid anion was fabricated successfully. The performance of the sensor was detected with the Keithley 2600A Source Meter. The experimental results show that the sensor has higher recognition for trichloroacetic acid anion and almost no recognition for dichloroacetic acid?sulfate and other interfering ions. This is because the ion imprinted polymers have special selectivity and recognition ability for the template ion. The sensitivity of AlInN/GaN HEMT sensor is 51.01?A·L/mg, the detection limited is 0.01 ?g/L. This shows the AlInN/GaN HEMT sensor can be fast and sensitive to the detection of trichloroacetic acid anion and provides a new method for on-line monitoring of the drinking water.