The Liquid Sensor Based On Sub-wavelength Slot Phononic Crystal

Fast, precise analyzing the component and characteristic of liquid play a critical role in numerous applications, including microbiology, environment monitoring and food quality control, which is an important development direction of the current and future sensor field. The basic mechanism of operation is that acoustic waves travel through the medium of interest thereby probing its acoustic properties, such as density, elastic moduli, speed of sound, viscosity, etc. The localized wave in the slot based on artificial structure(phononic crystal, metamaterial, etc.) can enhance the acoustic wave-matter interaction, and it is a new mechanisms to detect small changes.In this paper, the detection mechanism of liquid sensors based on sub-wavelength slotted phononic crystal system is researched and the corresponding key parameters are explored. Thus, the research provides fundamental physics support for high quality factor and high sensitivity sensors. The main work is as following:Firstly, the acoustic characteristic with double plate sub-wavelength slotted phononic crystal system is explored. The effect of surrounded by fluid system on acoustic performances is discussed. The results are that the advantages of the system are sub-wavelength dimensions, strong localized wave in the slot, and enhancing the acoustic wave-matter interaction. Meanwhile, the system is sensitive to the liquid mixtures, especially for these density and speed of sound variation on the contrary.Secondly, the different liquid sensors based on sub-wavelength slotted phononic crystal system are studied. The results are that the system has high quality factor 6095 and is sensitive to the liquid mixtures, especially for the fluid with density and speed of sound variation on the contrary. The resonance frequency shift relationship of the four kinds of sub-wavelength slotted phononic crystal materials with methyl methacrylate, pure aluminum, glass with high-borosilicate, monocrystalline silicon are simulated. And the resonance frequency of the four kind materials is analyzed. The results show that the best solid material of slotted phononic crystal system is silicon. Finally, the effect of different slot widths on resonance frequency of is simulated as well. The best slot width is about 50 micrometer.Thirdly, the effect of sub-wavelength slotted BST phononic crystal system on the liquid temperature sensor is studied. The results are that transmission spectrum is sharp and the system has high quality factor 12906. The resonance frequency varied obviously as the temperature changing from 293 K, 303 K to 313 K. Therefore, the system has high sensitivity 3.02 kHz/K. The effects of resonance frequency on sub-wavelength slotted BST phononic crystal system under different temperature and slot widths are simulated. The results are that BST ceramic material, furfural liquid and the slot widths all can change the resonance frequency of the sub-wavelength slotted BST phononic crystal system.In summary, the advantages of sub-wavelength slotted phononic crystal liquid sensor are compact size, high quality factor, and high sensitivity. In the future, it can be applied to chip technology, biological testing and miniaturization of medical technology.