Optimal Design Of Microfluidic Chip Based On Microcantilever Sensor

Traditional liquid detection of the microcantilever sensor mostly puts it on a special stage containing the sample,and then uses the atomic force microscope system to measure its deflection which aims to achieve liquid detection of the sample.However,this process cannot take advantage of the small size,fast convenient detection,and easy integration of the microcantilever,and also limits the application scenarios of the microcantilever sensor.Microfluidic chip detection technology has significant advantages such as high sensitivity,low detection limit,easy integration,and excellent compatibility,which can be widely used in the detection fields of chemistry,physics,and biology.In order to meet the needs of real-time and portable detection of the microcantilever,taking microcantilever sensor as the core,custom designing the microfluidic chip structure is an ideal solution for microcantilever sensor to get rid of the limitations in laboratory conditions and expand the detection application field.However,during the combined use of the microcantilever and the microfluidic chip,the liquid environment and fluid flow in the chip will affect the deflection,dynamic response,modal,frequency response of the microcantilever and other parameters that are closely related to the detection results.In view of the above problems in the integrated application process,this paper focuses on the microcantilever sensor with piezoelectric self-driving and piezoresistive self-sensing functions designed in the previous work of the research group.Based on the micro-nano fluid motion equation and diffusion mass transfer equation,using COMSOL Multiphysics software to establish the on-chip static and dynamic detection model of the microcantilever.Based on the on-chip static detection model of the microcantilever,the efforts of the sample flow velocity,the microchannel morphology size,the detection cell shape and the sensor fixed angle on the detection results were studied.Based on the on-chip dynamic detection model of the microcantilever,the effects of sample velocity,liquid environmental damping on its dynamic response characteristics and detection results were studied.Based on the simulation results,the structure and working conditions of the microfluidic chip with the microcantilever sensor as the core are determined as follows: For static detection,the microchannel of the detection cell is circular with diameter of 80 μm.The morphology of the detection cell is trapezoidal,and its upper bottom 280 μm,lower bottom 180 μm,height 280μm.The fixed angle of the sensor is 0°,and the flow rate of the sample is less than 4.71 μl/min.For dynamic detection,the amplitude of microcantilever beam decreases by 20% compared with air environment.The dynamic excitation frequency range in liquid environment is 50kHz~78 kHz and the typical value is 67.8 kHz.The dynamic excitation in air environment is115 kHz~132 kHz and the typical value is 124 kHz.The sample speed,detection cell,and channel size are the same as the static detection conclusions.Finally,according to the structural characteristics of microfluidic chip with microcantilever as the core,combined with the advantages of surface projection micro stereolithography 3D printing technology,microfluidic chip pretreatment and preparation scheme were proposed,microfluidic chip sample was successfully trial-produced.The microfluidic chip with microcantilever sensor as the core can further expand the detection field of microcantilever sensor.The realization and application of integrated microcantilever sensor has important practical significance for the improvement of MEMS technology.