Ultrasound Standing Wave Action on Suspensions and Biosuspensions in Micro- and Macro Fluidic Devices
June 7, 2010 — June 11, 2010
Coordinators:
- Jeremy J. Hawkes (University of Manchester)
- Juerg Dual (ETH Zentrum, Zuerich, Switzerland)
This course is aimed at PhD students and researchers with diverse backgrounds. It should also be of interest to academics and professionals who want to broaden their knowledge of the subject.
Standing wave vibrations are used by many groups to move both biological cells and other types of particles in liquids and gases, and also to move the liquids and gases themselves. Ultrasonic vibrations put larger forces on cells than lower frequencies and are generally preferred but, since their short wavelengths don’t actually move the cells very far microfluidic scale systems are the usual choice. In these sub millimiter channels processes have been established for: filtration, separation, transfer between two media, particle attraction to a wall (used to enhance cell capture by biosensors), mixing of fluids and reactants, forming patterns and stirring for enhanced heat transfer. At microfluidic scales an added advantage is that fluid movement is in the laminar flow regime and can be accurately predicted and modelled, so the potential for very precisely controlled systems exists.
More than 200 years ago Ernest Chladni reported moving particles in resonant fields yet only recently have a large number of potential applications reached the first proof of principle stage. The proofs demonstrate that manipulation by standing waves could accomplish many of the vital requirements for processing industries and also for medical and environmental monitoring, yet this approach has not been widely implemented. There are many reasons for this slow development, the main one being the large number of complex and interacting subjects which must be mastered to make progress. Since much of the information is not taught at undergraduate level students entering this area face a steep learning curve. This highly interdisciplinary course will explain how the acoustic radiation force acts on particles, how to identify and control the many forms of acoustic streaming, describe principles of resonance for the successful design of fluid containing resonators, and describe micro-engineering methods, system control and handling of biological samples. The course will also cover more general ground in fluidics and acoustics. In addition, to give an understanding of the potential applications many of the currently perceived requirements of microbiology, medicine and chemical engineering will be explained.
Work focused on a single purpose such as manipulation of particles is often disrupted by associated effects such as acoustic streaming, cavitation heating or particle-particle interaction. The aim of this course will be to give students sufficient knowledge to understand the many interacting events they will encounter during system development. Fully mastering and controlling all of these effects together is still a goal for the future but the course will show how to select out a phenomenon of interest and control it for many practical purposes.
Keywords: Vibrations of Solids and Structures, Wave Motions in Solids, Waves in Fluids, Solid Fluid Interactions