Development of Ultrasonic Devices for Microparticle and Cell Manipulation
An emerging demand for the precise manipulation of cells and microparticles for applications in cell biology and analytical chemistry has driven recent development of ultrasonic manipulation technology. Compared to the other major technologies used for cell and particle manipulation, such as magnetic tweezing, optical tweezing and dielectrophoresis, ultrasonic manipulation has shown excellent capabilities and flexibility in a variety of applications with its advantages of versatile, inexpensive and easy integration into microfluidic systems, maintenance of cell viability, and generation of sufficient forces to handle cells with dimensions up to tens of microns and agglomerates of a large number of cells. This thesis reviews current state-of-the-art of ultrasonic manipulation technology and reports the development of various ultrasonic manipulation devices, including simple devices integrated with high frequency (> 20 MHz) ultrasonic transducers for the investigation of biological cells and complex ultrasonic transducer array systems to explore the feasibility of electronically controlled 2-D and 3-D manipulation. Piezoelectric and passive materials, fabrication techniques, characterisation methods and possible applications are discussed. The behaviour and performance of the devices have been investigated and predicted in virtual prototyping with computer simulations, and verified experimentally. Issues associated during the development are highlighted and discussed. To assist long term practical adoption, approaches to low-cost, wafer level batch-production and commercialisation potential are also addressed.
Ultrasonic manipulation, Transducer arrays, Finite element analysis, Microfabrication
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