Sriphutkiat Yannapol, Zhou Yufeng
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Ave., Singapore Centre for 3D Printing (SC3DP), Singapore 639798, Singapore.
Sensors (Basel). 2017 Jan 7;17(1):106. doi: 10.3390/s17010106.
Accumulation of particles in a high concentration on a microchannel wall is a common phenomenon in a colloidal fluid. Gradual accumulation/deposition of particles can eventually obstruct the fluid flow and lead to clogging, which seriously affects the accuracy and reliability of nozzle-based printing and causes damage to the nozzle. Particle accumulation in a 100 μm microchannel was investigated by light microscopy, and its area growth in an exponential format was used to quantify this phenomenon. The effects of the constriction angle and alginate concentration on particle accumulation were also studied. In order to reduce the clogging problem, an acoustic method was proposed and evaluated here. Numerical simulation was first conducted to predict the acoustic radiation force on the particles in the fluid with different viscosities. Interdigital transducers (IDTs) were fabricated on the LiNbO₃ wafer to produce standing surface acoustic waves (SSAW) in the microchannel. It was found that the actuation of SSAW can reduce the accumulation area in the microchannel by 2 to 3.7-fold. In summary, the particle accumulation becomes significant with the increase of the constriction angle and fluid viscosity. The SSAW can effectively reduce the particle accumulation and postpone clogging.
在微通道壁上高浓度地积累颗粒是胶体流体中的常见现象。颗粒的逐渐积累/沉积最终会阻碍流体流动并导致堵塞，这严重影响基于喷嘴的打印的准确性和可靠性，并对喷嘴造成损坏。通过光学显微镜研究了100μm微通道中的颗粒积累情况，并以指数形式的面积增长来量化这一现象。还研究了收缩角和藻酸盐浓度对颗粒积累的影响。为了减少堵塞问题，本文提出并评估了一种声学方法。首先进行了数值模拟，以预测不同粘度流体中颗粒上的声辐射力。在LiNbO₃晶片上制作了叉指换能器（IDT），以在微通道中产生表面驻波（SSAW）。结果发现，SSAW的作用可使微通道中的积累面积减少2至3.7倍。总之，随着收缩角和流体粘度的增加，颗粒积累变得显著。SSAW可以有效减少颗粒积累并延缓堵塞。
