微流道精密磨削技术及自驱动检测芯片实验研究

Experimental study on grinding technology of microchannel for self-driven detection chip

针对病原体检测用芯片需要蠕动泵和离心机外加驱动的问题,设计微V槽流道的自驱动芯片,研究微液体流动的微流道拓扑结构及其精密磨削技术。因为激光等物理加工难以保证微拓扑结构精度,所以采用金刚石磨削技术实现石英玻璃表面的微V槽流道精密加工。基于多轴联动技术和机械物理去除原理开发了砂轮微尖端的高效精密在位修整工艺,可将磨粒精密修尖至同一角度,进行机械精密复制的塑性域微磨削。然后,实验分析微V槽流道的尖角、表面粗糙度、梯度等对微液体流速的影响。最后,制造出病原体检测的微流控芯片。研究结果显示,更大梯度、更小尖角和更小粗糙度以及尖角端分布的纳米流道可以大幅提高微液体流速。而且,微流道的V槽尖端半径为15μm,表面粗糙度为30 nm,可诱导微液体运动。在此基础上,研发的自驱动微流控芯片不需离心机就能够检测出布鲁氏菌的病原体核酸,检测灵敏度可以小于100 ag/μL。

Pathogen detectionrequires additional driving witha peristaltic pump and centrifuge.Hence,a self-driven microfluidic chip was designed with micro-V-groove channels,and its topologic structure and precision grinding were studied in relation to flow.Because it is difficult for physical processing,such as laser processing,to ensure topologic microform accuracy,diamond grinding was employed to machine the micro-V-groove channelsprecisely on a quartz glass surface.The key was to develop efficient and precision on-machine truing of a wheel-V-tip with the same grain-tip angle through multiaxis control and mechanical physical removal and subsequently to perform ductile-modemicrogrinding with mechanical precision copy.Furthermore,the influence of themicro-V-groove angle,roughness,gradient,etc.on microliquid flowing velocity were experimentally investigated.Finally,a microfluidic chip was manufactured for pathogen detection.It was found that larger gradient,smaller angle,finer surface roughness,and at-V-tip distributed nanochannels lead to a much larger flow velocity in the microfluidic chip.Accordingly,the micro-V-grooves can be ground to attain a surface roughness of 30 nm and tip radius of 15μm,which induces microliquid flow.As a result,the developed self-driven microfluidic chip can detect Brucella pathogen nucleic acids with a detection accuracy of 100 ag/μLor lesser without a centrifuge.