聚二甲基硅氧烷封装石墨烯基柔性红外探测器的制备及其应用

采用热还原法在不同退火温度(从100到1200℃)下制备了一系列还原氧化石墨烯(r GO)薄膜,并通过X射线粉末衍射(XRD)、傅里叶变换红外光谱(FTIR)、拉曼光谱、四探针电阻仪和扫描电镜(SEM)对其进行了表征和分析.随后利用旋涂封装法制备了聚二甲基硅氧烷(PDMS)封装的石墨烯基柔性红外探测器(P-r GO-P),并成功用于红外激光、人体红外辐射、弯曲变化和压力探测.实验结果表明,采用不同温度还原的rGO薄膜封装得到的P-r GO-P柔性红外探测器在近红外(1064 nm)激光照射下均有响应,其中最高的光响应可达2.78 mA/W.此外, P-rGO-P柔性探测器对人体红外辐射和弯曲变化也具有快速、灵敏的响应,并且经过反复弯折仍能保持完整性与响应能力.

Blockage effect on the flow around a cylinder probe in calibration

Flow around a 2-D cylinder pressure probe placed in uniform flow,free jet flow,and wind tunnel flow was analyzed with potential flow theory and simulated with numerical method.Blockage effect was investigated under several typical flow Mach numbers.The result from numerical simulation shows a similar trend to the one from potential flow method while varies in quantity.Wind tunnel walls accelerate the flow near the probe and thus produce a blockage effect;Boundary of free jet flow,however,decelerates the flow and thus produces a 'negative' blockage effect.A maximum incoming Mach number exists when the probe is calibrated in wind tunnel in high subsonic condition due to choking caused by shocks and shock induced separation.The critical Mach number varies with blockage ratio,which makes high Mach number impossible to achieve in large blockage ratio condition.The blockage effect itself is unavoidable for calibration or measurement although a sufficiently small blockage ratio brings minor effect.Correction can be implemented based on the numerical simulation result presented in this paper and further works.