Self-cleaning And Self-powered UV Sensors

Along with the rise of Information Revolution,the world has gradually stepped from the Industrial Age into the Information Age.In the Information Age,the first thing that needs to be solved is the acquisition of information.Therefore,sensors have drawn ever increasing attention and played an important role in personal daily life and industrial area.As a member of the family of sensors,the UV sensors have important applications in many areas such as missile warning,ultraviolet communication,battlefield environment monitoring and flame detection.Wireless Sensor Network which born from the joint of sensor technology,microelectric technology,wireless communication technology and embedded technology,can greatly improve the sensors' ability in acquiring information of the above-mentioned areas.The bottle neck that restricts the development of Wireless Sensor Network is the long power supply of individual node in the sensor network.With the propose of the nanogenerator which can harvest the ambient mechanical energy and convert it into electricity,the self-powered device which combine the nanogenertor with functional device give a potential solution to this bottle neck.With the development of nanogenerators,although there have some researches about self-powered UV sensors recently,studies on how to optimize the performance of individual component and how to achieve optimal performance as a whole are rarely reported.In this thesis,we carried out studies about high performance UV sensor with,the optimization of piezoelectric nanogenerator.And in order to avoid the self-powered device's performance degradation caused by the environmental dust pollution,we developed a self-cleaning film with high light transparency,and expanded the self-powered devices to self-cleaning and self-powered devices.Firstly,after analyzing the mechanism of ZnO UV sensing,we proposed the design about high sensitivity UV sensor,and fabricated a sensor with high sensitivity by studying the fabricating technique of ultra-thin and dense ZnO film.When illuminated by UV light with intensity of 0.1 mW/cm2 wavelength of 365 nm,this UV sensor achieved a sensitivity of 1.3 ? 106 which is 3 times higher than the record value for ZnO based UV sensors.On the basis of this,we fabricated a flexible UV sensor.Bending the sensor to a radius of curvature about 18.5 mm,the sensor's mechanical performance and sensitivity can be well maintained.Secondly,as for the piezoelectric nanogenerator(PENG),we systematically studied the influence of the form of external force on the PENG's dynamic electric output.After categorizing the ambient mechanical force into squared shaped force,triangular shaped force,and sinusoidal shaped force,we discussed the PENG's output character and gave the PENG's mean power dependence on the frequency of external force,resistance of external circuit when the PENG was driven by the above forces,respectively,and found that PENG driven by square shaped force driven can achieve the highest mean power.Finally,we verified the above conclusions by experiments.Thirdly,we did a systematic study about the self-powered UV sensor and found that the design that based on testing the PENG's electrical signal peak is better.After analyzing this design,we pointed out that as for the system driven by low frequency force,using the PENG's voltage peak to reflect the UV intensity is a better choice.After that,we constructed two kinds of self-powered sensor and gave a fitting formula combined with the above theoretical analysis,this formula can be used to calibrate the UV intensity.Fourthly,we fabricated a superhydrophobic self-cleaning film aiming to protect the optoelectronic devices against the performance degradation caused by the environmental dust.This self-cleaning film possesses a sling angle lower than 1? and a light transmittance higher than 88% when the light was in the range of 300 nm-800 nm.Applying the film on commercial solar cell,the solar cell's efficiency could restore to its original value after a self-cleaning process via water or wind.Finally,we combined the optimized BaTiO3/PDMS composite based PENG,ZnO UV sensor with high sensitivity and self-cleaning film together and fabricated a self-cleaning self-powered UV sensor than can quantitatively calibrate the UV light intensity.