Fluidic bypass structures for improving the robustness of liquid scanning probes
Upon analyzing failure modes and their causes in the operation of liquid scanning probes, two main modes were identified. These failure modes can be countered by a simple design element, a microfluidic bypass channel, which is straightforward to implement in most liquid scanning probe. The bypass can be operated in dc mode when filled with liquid or in ac mode when filled with gas. Each mode allows to prevent one of the two main failure modes. Presented analytical models, engineering design considerations and experimental verification enable a swift adaption of these bypass channels approach to increase operational robustness of liquid scanning probes.
A New RF Heating Strategy for Thermal Treatment of Atherosclerosis
Restenosis remains a challenge for treatment of atherosclerosis due to damage of the vascular endothelium and induced proliferation of the smooth muscle cell. A new thermal balloon is designed to selectively ablate the atherosclerosis plaque. The volume heating of RF currents is integrated with the surface convection of the internal cooling agent to focus the thermal energy on the plaque while sparing the vascular endothelium. Microelectrodes array is designed for the conformal treatment. The numerical study clearly illustrates the heating and regulating capacity of the design for different treatment necessities. With its further development, a precision thermal treatment of atherosclerosis resistive to restenosis may be realized.
3D Microwave Tomography Using the Soft Prior Regularization Technique: Evaluation in Anatomically-Realistic MRI-Derived Numerical Breast Phantoms
MRI breast images with microwave tomography is combined through a soft prior technique, incorporating spatial information from MRI into the regularization process of the image reconstruction algorithm. Numerical experiments were completed on MR-derived 3D breast geometries with different parenchymal densities, as well as a simulated tumor. When the soft prior technique was applied, relative root mean square error values decreased in all cases across all breast densities. The incorporation of structural priors significantly increased the recovered contrast between tumor and fibroglandular tissue. This study confirmed that the soft prior regularization algorithm is robust in our 3D microwave image reconstruction.
Three-Dimensional Electrical Impedance Tomography with Multiplicative Regularization
We applied the multiplicative regularization scheme to the image reconstruction of electrical impedance tomography (EIT) to alleviate its ill-posedness. In this scheme, an objective function is constructed in which the data misfit function is multiplied by a regularization function. The main advantage of this scheme over the additive regularization scheme is that no artificial regularization parameter needs to be set in the objective function. Based on the multiplicative scheme, we formulated both the absolute and difference image reconstruction problems. Numerical and experimental results show the promising application of this scheme for thoracic imaging.
Correlation Between Optical Fluorescence and Microwave Transmission During Single-cell Electroporation
In this study, multimodal characterization of a mammalian cell by optical and microwave techniques simultaneously during electroporation. Using a coplanar waveguide with a Jurkat cell trapped in the middle of its center conductor, continuous waves at 100 kHz of different amplitudes were applied for 20 s to porate single cells while microwave transmission coefficients at 9 GHz were measured every 0.4 s. The onset of electroporation was indicated by abrupt changes in both fluorescence intensity and transmission coefficient. Experimental results show that the transmission coefficient could serve as a label-free indicator of cell membrane permeability during and after electroporation.
A New Image Similarity Metric for Improving Deformation Consistency in Graph Based Groupwise Image Registration
Image similarity metric (ISM) is used to construct the graph of input images in graph based groupwise image registration (G-GIR). Most existing G-GIR methods adopt image intensity-based ISM. However, image intensity is not directly related to deformation directions in image registration, and inconsistent deformation along the shortest paths in the resulting graph is inevitable, making G-GIR inefficient and inaccurate. We propose a new ISM to build the graph with deformation consistency. Our ISM reduces inconsistent deformation and improves registration outcome.