Sensory-Hair-Based Flow Sensor

制作了一种由悬臂梁和应变片组成的感觉毛发结构流量传感器。悬臂的长度为1.5 mm，宽度为600 μm，厚度为80 μm，由SU-8制成，SU-8通常用于制造具有高纵横比的微结构。在悬臂梁底部采用Au/Cr薄膜制作应变片，其电阻变化率与悬臂梁挠度呈线性关系。虽然该传感器的测量系数很小，但它与硅应变计一样敏感，因为悬臂材料SU-8的杨氏模量比硅的小两位数，因此悬臂梁更容易偏转。当空气和其他流体接近悬臂梁时，悬臂梁被弯曲，通过悬臂梁的挠度来测量流量。在此基础上，设计了一种基于半规管结构模型的角加速度传感器。流量传感器安装在宽度为2mm，半径为5mm的圆形通道的侧壁上。当对通道施加角加速度时，填充在通道内的液体的运动引起悬臂梁的挠曲和应变片电阻的变化。角加速度16.7 rad/sec^2产生的电阻变化，放大300后转化为近20 mV的输出电压。该传感器在响应性方面不太敏感，因为它依赖于液体运动。然而，它保留了一个很大的优势，允许更小的串扰与角加速度围绕其他轴。

A flow sensor with a sensory hair structure consisting of a cantilever and a strain gauge was fabricated. The cantilever measured 1.5 mm in length, 600 μm in width, and 80 μm in thickness, and was made of SU-8 which is often used for fabrication of microstructures having high aspect ratios. The strain gauge was made of Au/Cr thin film at the bottom of the cantilever, and showed a linear relationship between the rate of change of its resistance and deflection of the cantilever. Although the fabricated sensor had a small gauge factor, it was as sensitive as that of a silicon strain gauge because the cantilever material, SU-8, had smaller Young's modulus by two digits compared to that of silicon, and therefore the cantilever was much easier to deflect. When air and other fluids approached the cantilever, it was bent and the flow rate was measured by deflection of the cantilever.Moreover, a sensor for detecting angular acceleration based on a semicircular canal structure model was developed using the technique described above. The flow sensor was attached to the sidewall of a circular channel of 2 mm in width and 5 mm in radius. When an angular acceleration was applied to the channel, motion of the liquid filled inside the channel caused deflection of the cantilever and change in resistance of the strain gauge. The angular acceleration of 16.7 rad/sec^2 generated resistance change which was then converted to an output voltage of nearly 20 mV when amplified by 300. The sensor is less sensitive in terms of responsiveness because it relies on liquid motion. However, it retains a big advantage of permitting much smaller cross-talk with angular accelerations around other axes.