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污染物对热膜式气体流量传感器精度的影响 被引量:3
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作者 袁昌荣 孙中圣 李小宁 《中南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2020年第2期367-376,共10页
为了预测污染物对热膜式气体流量传感器精度的影响,研究传感器精度下降机理。首先,分析传感器测量原理,建立传感器电压输出理论数学模型,并基于绕流理论推导气体流经污染物后流速公式;然后,搭建污染物颗粒累积试验平台,进行长时间颗粒... 为了预测污染物对热膜式气体流量传感器精度的影响,研究传感器精度下降机理。首先,分析传感器测量原理,建立传感器电压输出理论数学模型,并基于绕流理论推导气体流经污染物后流速公式;然后,搭建污染物颗粒累积试验平台,进行长时间颗粒累积试验,验证理论模型合理性。研究结果表明:传感器的输出电压与所测气体流速、基底隔膜厚度以及导热系数有关;气体流速下降幅度随污染物高度增加而增大,随污染物与加热电阻中心距离增加而减小;污染物颗粒主要围绕热膜电阻周边呈“U”型分布,热膜电阻上方基本无累积,说明传感器精度下降主要是由热膜电阻前端累积的污染物改变气流流速所致;传感器电压输出理论计算值和试验测量值相吻合,证实了理论模型的合理性。 展开更多
关键词 热膜式 气体流量传感器 芯片污染 累积厚度 精度
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密立根法测量热膜式气体流量传感器中污染物颗粒带电量 被引量:2
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作者 袁昌荣 李小宁 孙中圣 《机械科学与技术》 CSCD 北大核心 2021年第5期775-779,共5页
热膜式气体流量传感器在实际使用过程中,其芯片表面很容易被微小颗粒污染,使精度达不到工作要求。试验研究发现,传感器通电工作时,芯片表面电场力是造成污染物颗粒吸附堆积的主要因素。因此,污染物颗粒带电量的大小对芯片表面颗粒的堆... 热膜式气体流量传感器在实际使用过程中,其芯片表面很容易被微小颗粒污染,使精度达不到工作要求。试验研究发现,传感器通电工作时,芯片表面电场力是造成污染物颗粒吸附堆积的主要因素。因此,污染物颗粒带电量的大小对芯片表面颗粒的堆积有着直接影响。文中采用Mastersizer 2000激光粒度分析仪和密立根油滴仪联合测量了颗粒群的平均粒径和平均带电量。激光粒度分析仪所测污染物颗粒的平均粒径为3.311μm,根据此平均粒径值,密立根油滴仪所测3.2~3.4μm范围内的颗粒所带平均带电量为6.4×10^(-17) C,此带电量即为整个颗粒群的平均带电量。 展开更多
关键词 热膜式气体流量传感器 芯片污染 颗粒粒径测量 颗粒带电量测量 密立根法
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Surface-imprinted polymers in microfluidic devices 被引量:4
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作者 SCHIRHAGL Romana ZARE Richard N. 《Science China Chemistry》 SCIE EI CAS 2012年第4期469-483,共15页
Molecularly imprinted polymers are generated by curing a cross-linked polymer in the presence of a template. During the curing process, noncovalent bonds form between the polymer and the template. The interaction site... Molecularly imprinted polymers are generated by curing a cross-linked polymer in the presence of a template. During the curing process, noncovalent bonds form between the polymer and the template. The interaction sites for the noncovalent bonds become "frozen" in the cross-linking polymer and maintain their shape even after the template is removed. The resulting cavities reproduce the size and shape of the template and can selectively reincorporate the template when a mixture containing it flows over the imprinted surface. In the last few decades the field of molecular imprinting has evolved from being able to selectively capture only small molecules to dealing with all kinds of samples. Molecularly imprinted polymers (MIPs) have been generated for analytes as diverse as metal ions, drug molecules, environmental pollutants, proteins and viruses to entire cells. We review here the relatively new field of surface imprinting, which creates imprints of large, biologically relevant templates. The traditional bulk imprinting, where a template is simply added to a prepolymer before curing, cannot be applied if the analyte is too large to diffuse from the cured polymer. Special methods must be used to generate binding sites only on a surface. Those techniques have solved crucial problems in separation science as well as chemical and biochemical sensing. The implementation of imprinted polymers into microfluidic chips has greatly improved the applicability of microfluidics. We present the latest advances and different approaches of surface imprinting and their applications for microfluidic devices. 展开更多
关键词 molecular imprinting microfluidic devices surface imprinting bioanalysis separation sensors
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