考虑中性层位置变化的微悬臂梁气体传感器静态模型的分析

微悬臂梁是一种高灵敏度的生化传感器。本文考虑吸附表面应力引起的中性层位置的变化，采用能量法建立了微悬臂梁在单层分子吸附稳定后的静态弯曲模型，并以表面吸附有水蒸汽分子的微悬臂梁为例，研究了微悬臂梁曲率半径随其厚度、杨氏模量及吸附分子间距的变化规律以及中性层位置变化对微悬臂梁传感器性能预测的影响，结果发现：1)微悬臂梁的曲率半径与其杨氏模量、厚度及吸附分子间距之间可以近似用一次、二次和八次函数关系表示；2）中性层变化导致的曲率半径计算误差，随着微悬臂梁厚度、杨氏模量的增加而减小，但影响较小，而吸附分子间距会对该相对误差产生明显影响；3）中性层位置变化会对微悬臂梁传感器灵敏度和表面应变预测产生明显的影响。

ANALYSIS OF STATIC BENDING MODEL OF MICROCANTILEVER GAS SENSOR CONSIDERING THE CHANGE OF NEUTRAL LAYER POSITION

Microcantilever is a kind of biochemical sensor with high sensitivity.In this paper,the change of neutral layer position caused by adsorption-induced stress is introduced into modeling,and the static bending model of microcantilever with monolayer molecules is established based on energy method.On this basis,the relationship between the curvature radius of microcantilever and its thickness,Young’s modulus and adsorbed molecules distance and the effect of change of neutral layer position on the performance prediction of microcantilever are investigated using the microcantilever adsorbed with water molecules.The results show that:(1)the relationship between the curvature radius and Young’s modulus,thickness and adsorbed molecules distance can be expressed using the linear,quadratic and eight approximation function;(2)the predicted error of bending curvature radius caused by the change of neutral layer position slightly increases with decreasing Young’s modulus and thickness,whereas the effect of distance between adsorbed molecules on the error is significant;(3)the change of neutral layer position can significantly affect the sensitivity and surface strain of the microcantilever.