nano-Particle Resonance Imaging

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This is a strong industrial demand for on-line characterisation of particle size and concentration distribution in chemical engineering processes, e.g. the precipitation or crystallisation process in pharmaceutical or nuclear fuel industries. The currently available techniques are mostly in the type of sampling and off-line analysis. There is no on-line device for nano-particle characterisation. Another common features of these imaging systems is that they measure the same form of energy as the type of the excitation. Therefore, it may have difficulties in the separation of the excitation and responding variables in the use of the frequency domain analysis. The resolution of this type imaging methods is also constrained by their physical limitation, e.g. the wavelength and intensity of the excitation signal in optical imaging methods.The size and density of particles are normally different from those of ions in colloids. The distribution of charges carried by ions is in exponential decay with the distance from the particle surface. Under an external force, they will move with different acceleration and terminal speeds, or vibrate with different amplitudes and phase lags in the case of an alternating force. The differences in the acceleration and terminal speeds, or the amplitudes and phase lags reflect the properties of particles' zeta-potential, size and density. The research proposed is to utilise the unique features of particles in colloids for indirect imaging of characteristic distribution of nano-particles. The indirect imaging method is based on the concepts ofa)the vibration of electric charged particles in colloids energized by an external force;b)the energy conversion due to the vibration of charged particles;c)the resonance principle for maximising the signal strength;d)the tomographic reconstruction to position the vibration. The proposed PRI method has unique advantages at a)the separation of excitation and responding variables;b)the correlation of particle size and density;c)the reflection of particle-particle interaction;d)the resolution selective based on either excitation or responding field.Through the appreciated approach, the proposed Particle Resonance Imaging (PRI) may lead to a new indirect imaging method and provide a highly desirable and powerful on-line particle analysis tool to meet the emergent requirement from pharmaceutical, nuclear and other wide range industries.