Department of Applied Physics, Aalto University , P.O. Box 15100, 02150 Espoo, Finland.
Department of Bioproducts and Biosystems, Aalto University , P.O. Box 16000, 02150 Espoo, Finland.
Langmuir. 2017 Jun 27;33(25):6300-6306. doi: 10.1021/acs.langmuir.7b01327. Epub 2017 Jun 14.
The damped oscillations of liquid-immersed ferrofluid sessile droplets were studied with high-speed imaging experiments and analytical modeling to develop a novel microrheology technique. Droplet oscillations were induced with an external magnetic field, thereby avoiding transients in the resulting vibrational response of the droplet. By following the droplet relaxation with a high-speed camera, the frequency and relaxation time of the damped harmonic oscillations were measured. We extend upon existing analytical theories to describe our liquid-immersed sessile droplet system, and directly quantify the droplet relaxation with the viscosity of the internal and external fluid as well as the interfacial tension between these. The easily controllable magnetic droplets make our oscillating ferrofluid droplet technique a potential candidate for high-throughput microrheology and tensiometry in the future.
用高速摄像实验和分析模型研究了浸液铁磁液滴的阻尼振荡，以开发一种新的微流变技术。通过外加磁场诱导液滴振荡，从而避免了液滴振动响应中的瞬变。通过高速摄像机跟踪液滴的弛豫，可以测量阻尼谐波振荡的频率和弛豫时间。我们扩展了现有的分析理论来描述我们的浸液固着液滴系统，并直接用内部和外部流体的粘度以及它们之间的界面张力来定量描述液滴的弛豫。这种易于控制的磁性液滴使得我们的振荡铁磁液滴技术成为未来高通量微流变学和张力测量的潜在候选者。
