Preparation Of Silicon Nanowires Array Sensor And Design Of Multi-dimensional Force Sensor Based On MEMS

MEMS sensors are significant force to promote the fourth industrial revolution,attributing to small size,excellent reliability,high sensitivity and easy-integration.And MEMS sensors have been widely used in the detection of various physical,chemical and biological signals.Alpha Fetoprotein and Carcinoembryonic Antigen are two meritorious tumor markers for diagnosing liver cancer.However,general clinical detection methods for AFP and CEA have some shortcomings,such as low sensitivity,being time-consuming,involving labels and requiring expensive equipment.Aiming at the above shortcomings,a MEMS-based Si NWs array sensor was developed to realize highly sensitive,real-time,label-free and low-cost detection of AFP and CEA in this paper.Meanwhile,to verify the high performance of Si NWs array sensor,a gold-electrode-based electrochemical method was used to detect AFP for verification experiments.Moreover,Si NWs array can amplify the signals compared with single Si NW,but there is a certain degree of signal coupling under multi-signal detection.Therefore MEMS sensors with self-decoupling function were designed in this paper.The specific research contents were as follows:(1)The performance characterizations of Si NWs array sensors,including morphology,electrical characteristics,p H characteristics,and hydrophilicity.The scanning electron microscopy,the contact angle measuring instrument PZ-200 SD and the digital source-meter Keithley 2450 were used to characterize the morphology,electrical characteristics,p H characteristics and hydrophilicity of the prepared Si NW array sensor respectively.The results showed that the size of prepared Si NWs array were consistent,about 80 nm.Meanwhile,the Si NWs array sensors exhibit excellent MOSFET characteristics and are very sensitive under liquid phase conditions.After silanization modification,the sensor can sensitively identify the change in p H.Oxygen plasma treatment can enhance the hydrophilicity of Si NWs array.(2)Detection of AFP and CEA based on Si NWs array sensor and experimental verification.The detection limit of the sensor for AFP is as low as 0.00654 fg/m L,with a linearity of 0.99885(from 0.1 fg/m L to 100 pg/m L);the detection limit for CEA is 0.152 fg/m L,with a linearity of0.97677(from 1 fg/m L to 10 pg/m L).In addition,Si NWs array sensors show excellent specificity for AFP and CEA,and have good stability and reproducibility.To further verify the high-performance detection of Si NW array sensor to AFP,a gold-electrode-based electrochemical method was used to detect AFP for comparative experiments.The comparison results reveal that the Si NWs array sensor has more advantages,such as CMOS compatibility,high sensitivity,real-time detection,no labels,low cost and high detection efficiency.(3)Based on the disadvantage that Si NWs array sensor has a certain degree of multi-signal coupling,the decoupling applications of silicon-based sensors were expanded.By optimizing the sensor structure,silicon-based two-dimensional force,three-dimensional force,and two-dimensional torque sensors that can realize force/torque decoupling were designed.The principle of decoupling is to ensure that one input only corresponds to one larger output and suppress other outputs.In addition,the MEMS preparation process of two-dimensional force sensor,two-dimensional torque sensor and three-dimensional force sensor were designed.Since interdimensional coupling is suppressed,the designed decoupling structure will effectively improve the accuracy of the sensor.