| The manipulation of micro and sub-micrometer inorganic and organic particles at a solid-sample interface is important in many modern biomedical technologies, including biosensors and biochips, tissue engineering, drug delivery and MEMS. Currently available manipulation techniques such as Atomic Force Microscopy (AFM) and the techniques based on optical, magnetic, electrokinetic, and acoustic phenomena exhibit limitations related to stringent requirements on the properties of the particles, samples, as well on operational, experimental and environmental conditions. To overcome some of these limitations, a simple and versatile, technique called the Piezoelectric Interfacial Particle Manipulator (PIPM) is proposed. The PIPM principle of operation is based on an efficient generation of interfacial manipulation forces, at distances ranging from 0.5-50mum from the manipulator surface, which are capable of producing a broad range of particle motion in 3-D space. These forces, piezoelectrically generated by multi-modal surface vibration, can be applied to any type of the substrate on which manipulation is required. A theoretical study of the interfacial forces between the particle and the PIPM surface, and a finite element modeling of the P1PM-generated force pattern provide both formal and phenomenological models that enable understanding of the mechanism of particle manipulation as well deliver the criteria for a PIPM design. The PIPM was successfully tested with inorganic (5-50microm) and organic particles (0.5-5microm) that included stainless steel and silica microparticles as well bacteria spores. The PIM results were positively confirmed using standard laboratory instrumentation like atomic force microscope (AFM). The integration of the PIPM with a biosensor (TSM thickness shear mode sensor) demonstrated an improvement of up to 40% in analyte detection. The obtained results demonstrate that the PIPM provides the means for reproducible, high throughput manipulation of microparticles without stringent environmental and particle property XXIV requirements. Specifically, it provides a large array of manipulation modalities such as controllable sample delivery, concentration control, mixing and sorting on a single substrate that should find applications in development of broad range of industrial and biomedical devices, including various sensing structures based on piezoelectric, optical or magnetic principles of operation, biochips and bio-actuators.Keywords: Manipulation, AIM, FHA, TSM, piezoelectric... |
