Dynamic stressing measurement of viscous liquids using microfluidic chips

This paper demonstrates the dynamic stressing of viscous liquids in microfluidic channels. An infrared laser pulse is focused within the testing liquid in a microfluidic channel and a spherical shock wave near an air-liquid interface is created. The shock is reflected as a tension wave by the free surface due to the acoustic impedance mismatch. The displacement of the free surface within hundred nanoseconds is captured by a developed double-exposure optical system. The tensile strength can be estimated by extrapolating a series of shock pressure approximation at several different distances between the bubble and the free surface to the measurement accuracy. This study has a great potential in the optical breakdown of biomaterials.