APPLICATION OF HYDROELASTICITY AT MICROSCALE FOR FLOW CONTROL AND MICROMIXING
Zhiping Wang1, Huanming Xia2
1Singapore Institute of Manufacturing Technology, A*STAR, Singapore;
2Nanjing Univesity of Science and Technology, China
Hydroelasticity is concerned with the deformations of elastic bodies responding to hydrodynamic excitations and simultaneously the modification of these excitations owing to the body deformation. The problems of hydroelasticity are coupled, which implies
that the elastic deformations of the body depend on the hydrodynamic forces and vice versa. Hydroelasticity has been used in our microfluidics design for flow control and micromixing. A pressure driven passive micro-oscillator, making use of the interactions of hydrodynamic, elastic and inertial forces, has been developed to convert stead laminar flow to oscillatory flow in microchannels. A simple geometric design with a diaphragm generates an alternating flow with a frequency between 10 Hertz to 1000 Hertz. Analog to an electric circuit, the micro-oscillator consists of a fluid capacitor and a fluid resistor, for which the fluid resistance changes with the deformation of diaphragm. Under a given geometry, oscillation takes place when the flow pressure reaches a critical value and the system is biased into a negative differential resistance region.
The micro-oscillator is a basic element of a fluid circuit. The oscillation flow can be designed for rapid mixing when it meets with another stream of liquid. This phenomenon has been used for anti-solvent precipitation of solid-lipid nanoparticles. It shows that within a wide concentration range from 10 to 300 mg/ ml, solid lipid particles of 50~240 nm can be produced with the polydispersity index ranging from around 0.16 to 0.26.
In this talk, the latest design of a hydroelasticity-based micro-oscillator, its mechanism and applications will be presented.