摘要
按重视的是外形尺寸还是内在微特性,把微系统分成微外形系统和微特性系统,通过比较分析,得到后者的存在普遍性比前者广而且外形大小与内在微特性好坏无直接联系的结论。就微物质传输和微传热常见的细长流道低雷诺数内流条件,提出微流动、微结构、微综合等3方面的微特性。研究了微系统中和低速流动中合理流动形态的概念,提出了人为地产生和利用可预测可控制小幅脉冲流动序列是解决微流体流动不正常这一本质困难钥匙的思考。按所提出的3方面微特性对现有微流体影响方法进行了评价,并指出了我们的微流体数字化(digitalizationofmicrofluids)与Kim的数字化微流路(digitalmicrofluidiccircuits)在各方面的不同。提出了基于脉冲惯性力的微流体脉冲影响方法及其装置,实验结果表明多方面微特性俱好,流动正常性好,分辨率达fL级,最低流量达3pL/min,流动阻力降低,扰动性好,能实现微流道中和微射流中数字化流动,能实现裸微结构的数字化器件,方法普适于普通液体和粉体的驱动、控制和扰动,对流体性质无特殊限制,工作可靠性、生产率、可自动化性均较高。
We classify the micro systems into two categories, the micro over-all systems and the micro characteristic ones, in the former the over-all sizes must be small and in the latter other and more intrinsic micro characteristics are emphasized. By comparing them, we found that the latter are more universal and that smaller over-all sizes do not lead to better intrinsic characteristics in most cases. We proposed that three micro characteristics, the micro flowing, micro structure and micro comprehensive ones, should be considered for inner flowing under very low Reynolds number Re, which occurs often in fine-long conduits and in micro substance transport and micro heat transfer. We studied the concept of reasonable flowing form for fluids that flow in micro systems or with very low velocities, and put forward the idea that the flowing pulse sequences, which are predictable and controllable and which are produced artificially, may become the key of dealing with the most intrinsic difficulty in the field of microfluidic systems that micro flowing readily loses its normality. The existent methods were evaluated of influencing, that is, driving, controlling or disturbing, micro fluids according to the three micro characteristics mentioned above, and the differences between our digitalization of microfluids and Kim＇s digital microfluidic circuits were pointed put. Then we advanced the pulse influencing method, which is based on pulse inertia force, and its devices. Experimental results showed that the micro characteristics are satisfactory in many respects： the flowing normality holds in a wide frequency range, the substance transport resolution reaches the fL order, the minimum flow rate is 3 pL/min, the flowing resistance is minimized especially for fine-long conduits, digital fluidic flowing is realized both in micro conduits and in micro jet streams, some digital microfluidic components with neither micro movable parts nor embedded micro electric circuits have been made, the method is suitable universally for ordinary liquid and solid powder driving, controlling and disturbing purposes, no special properties of liquids and solid powders are required, and, finally, higher reliability, productivity and automaticity have been reached.
出处
《科技导报》
CAS
CSCD
2005年第8期4-9,共6页
Science & Technology Review
基金
国家自然科学基金项目(50275079)
国家"863"计划项目(2001AA423220)
关键词
粘性流体力学
微流体数字化
微特性
低雷诺数内流
脉冲惯性力
普通液体
粉体
viscous fluid mechanics, digitalization of microfluids, micro characteristics, inner flowing under low Reynolds numbers, pulse intertia forces, ordinary liquids, solid powders
