bin Jia

A Miniature Electrical Impedance Tomography Sensor and 3-D Image Reconstruction for Cell Imaging

Real-time quantitative imaging is becoming highly desirable to study nondestructively the biological behavior of 3-D cell culture systems. In this paper, we investigate the feasibility of quantitative imaging/monitoring of 3-D cell culture processes via electrical impedance tomography (EIT), which is capable of generating conductivity images in a non-destructive manner with high temporal resolution. To this end, a planar miniature EIT sensor amenable to standard cell culture format is designed, and a 3-D forward model for the sensor is developed for 3-D imaging. Furthermore, a novel 3-D-Laplacian and sparsity joint regularization algorithm is proposed for enhanced 3-D image reconstruction. Simulation phantoms with spheres at various vertical and horizontal positions were imaged for 3-D performance evaluation. In addition, experiments on human breast cancer cell spheroid and a triangular breast cancer cell pellet were carried out for experimental verification. The results have shown that the stable measurement on high conductive cell culture medium and the significant improvement of image quality based on the proposed regularization method are achieved. It demonstrates the feasibility of using the miniature EIT sensor and 3-D image reconstruction algorithm to visualize 3-D cell cultures, such as spheroids or artificial tissues and organs. The established work would expedite real-time quantitative imaging of 3-D cell culture for assessment of cellular dynamics.

Impedance-based cellular assays for regenerative medicine

Therapies based on regenerative techniques have the potential to radically improve healthcare in the coming years. As a result, there is an emerging need for non-destructive and label-free technologies to assess the quality of engineered tissues and cell-based products prior to their use in the clinic. In parallel, the emerging regenerative medicine industry that aims to produce stem cells and their progeny on a large scale will benefit from moving away from existing destructive biochemical assays towards data-driven automation and control at the industrial scale. Impedance-based cellular assays (IBCA) have emerged as an alternative approach to study stem-cell properties and cumulative studies, reviewed here, have shown their potential to monitor stem-cell renewal, differentiation and maturation. They offer a novel method to non-destructively assess and quality-control stem-cell cultures. In addition, when combined with in vitro disease models they provide complementary insights as label-free phenotypic assays. IBCA provide quantitative and very sensitive results that can easily be automated and up-scaled in multi-well format. When facing the emerging challenge of real-time monitoring of three-dimensional cell culture dielectric spectroscopy and electrical impedance tomography represent viable alternatives to two-dimensional impedance sensing. This article is part of the theme issue ‘Designer human tissue: coming to a lab near you’.

Electrical Resistance Tomography Sensor for Highly Conductive Oil-Water Two-Phase Flow Measurement

Oil-water two-phase flows are encountered in various process industries, such as petroleum and chemical. The measurement of oil volume fraction and its distribution is of particular importance for managing oil production and water disposal and/or water reinjection. The water phase in these environments always has high electrical conductivity, which incurs significant difficulties for oil volume fraction measurement using electrical resistance tomography (ERT). In this paper, a method of solving this problem is introduced. A pilot plant scale flow loop at TUV NEL Ltd. was used to measure oil distribution and oil volume fraction in the range of 0–0.4. The total volumetric flow rate of oil and water was 30, 60, and 90

Image Reconstruction for Electrical Impedance Tomography Using Enhanced Adaptive Group Sparsity With Total Variation

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Correlation of Volume Ratio and Normalized Permittivity in Particle Mixture

/h. High-electrical conductivity of water in 27.6 mS/cm was applied as continuous phase. The measurement results from ERT were validated by the readings of NEL’s references and flow patterns were compared with visual observation, which demonstrated that ERT was able to visualize the oil phase distribution and monitor the local and overall oil volume fraction up to 0.4.

Effect of packing and liquid conductivity on gas distribution and holdup in reaction column

A novel image reconstruction algorithm for electrical impedance tomography using enhanced adaptive group sparsity with total variation constraint is proposed in this paper. The new algorithm simultaneously utilizes the prior knowledge of regional structure feature and global characteristic of the conductivity distribution. The regional structure feature is encoded by using an enhanced adaptive group sparsity constraint. Meanwhile, the global characteristic of inclusion boundary is considered by imposing total variation constraint on the whole image. An enhanced adaptive pixel grouping algorithm is proposed based on Otsu’s thresholding method, which demonstrates good noise immunity. An accelerated alternating direction method of multipliers is utilized to solve the proposed problem for a faster convergence rate. The performance of the proposed algorithm is thoroughly evaluated by numerical simulation and experiments. Comparing with the state-of-the-art algorithms, such as the L1 regularization, total variation regularization, and our former work on adaptive group sparsity, the proposed method has demonstrated superior spatial resolution and better noise reduction performance. Combined with the total variation constraint, distinct boundary of inclusions has also been obtained.

Design and fabrication of microelectrodes for electrical impedance tomography of cell spheroids

The volume ratio in the total solid particle mixture is an important parameter indicating the characteristics of particulate mixtures. Therefore, a simple measurement method is desirable. In this paper, the normalized permittivities of two groups of particle mixtures are tested using electrical capacitance tomography (ECT) with the series and parallel models. The experimental results show that normalized permittivity changes obtained from the series ECT model have a very strong linear relationship with the volume ratio of higher permittivity materials in the mixture. The Maxwell Garnett formula can predict the normalized permittivity only after the permittivity of each type of particle is known. The comparison between two methods suggests that ECT with the series model is a better way to monitor the volume ratio in mixtures comprising two different types of solid particle.

Real-Time Wind Velocity Monitoring Based on Acoustic Tomography

In the packed reaction column, constant packing is always added to improve contact areas between two phases of chemical or similar processes, such as absorption, stripping, and distillation. In this paper, gas distribution and overall holdup were measured by Electrical Resistance Tomography (ERT). The bubble column was packed with or without 6 mm glass beads and liquid conductivity varied from 1.446 mS/cm to 80.1 mS/cm. Experimental results demonstrate that packing structure have stronger impact on gas distribution and overall holdup in the bubble column than the conductivity of aqueous solution. Some similar research findings were reported in literature, which proves ERT is an efficient imaging tool for real-time monitoring and helps to understand complex two-phase flow.

Exploring the Potential of Electrical Impedance Tomography for Tissue Engineering Applications

Three-dimensional (3D) tumour spheroids exhibit great potential as an in vitro for pharmaceutical drug testing. Spheroids represent more physiologically relevant systems compared to 2D cell culture models. In this work, MCF7 spheroids are cultured in Corning® spheroid microplates to investigate cell morphology and proliferation. Platinum microelectrodes designed to enable electrical impedance tomography (EIT) imaging were fabricated on glass substrates. EIT measurements were performed on 250 μm radius circular electrode tips for 0.71 mm MCF7 spheroid at 20 kHz using time difference imaging method. Initial results indicate the capability of EIT to image cell spheroids.

Image Reconstruction in Electrical Impedance Tomography Based on Structure-Aware Sparse Bayesian Learning

Wind-related disasters cause tremendous loss around the world, therefore a fast, low-cost but accurate wind velocity monitoring technique is highly desirable and will provide great benefits for wind risk management. Acoustic travel-time tomography, which utilise the dependence of sound speed on the wind velocity along the sound propagation path, is considered to be a promising remote sensing technique for wind velocity monitoring. The success of acoustic tomography technique stems from then various advantage of non-invasive, low cost and easy to implement when compared to other techniques. This chapter describes the fundamentals of the simultaneously multi-channel time-of-flight measurements and the tomographic reconstruction of 2D horizontal wind velocity distributions based on the use of offline iteration method. The feasibility and effectiveness of the proposed methods will be numerically validated in a simulation study.