Design and modeling of tunable microfluidic devices for label-free separation of circulating tumor cells

Reliable separation and detection of circulating tumor cells from blood cells are crucial for early cancer diagnosis and prognosis. Many conventional microfluidic platforms take advantage of the size difference between particles for their separation, which renders them impractical for sorting overlapping-sized cells. To address this concern, a hybrid inertial-dielectrophoretic microfluidic chip is proposed in this work for continuous and single-stage separation of lung cancer cell line A549 cells from white blood cells of overlapping size. The working mechanism of the proposed spiral microchannel embedded with planar interdigitated electrodes is validated against the experimental results in the existing literature. A numerical investigation is carried out over a range of flow conditions and electric field intensity to determine the separation efficiency and migration characteristics of the cell mixture. The results demonstrate the unique capability of the proposed microchannel to achieve high-throughput separation of cells (~0.7mL/min) at low applied voltages (~10V) in both vertical and lateral directions. A significant lateral separation distance between the CTCs and the WBCs has been achieved, which allows for high-resolution and effective separation of cells. The separation resolution can be controlled by adjusting the strength of the applied electric field. Furthermore, the results demonstrate that the lateral separation distance is maximum at a voltage termed as the critical voltage, which increases with the increase in the flow rate. Moreover, several electrode configurations have been studied and it was found that better separation can be achieved with higher number of electrodes and also positioning the electrodes towards the beginning of the channel makes them more effective for cell separation. Additionally, the robustness of the system was studied by using a mixture of WBCs containing four main subtypes having different sizes and dielectric properties. The electrode embedded spiral microchannel was successful in separating the CTCs from the mixture of WBCs. The proposed microchannel and the developed technique can provide valuable insight into the development of a tunable and robust point-of-care device for effective and high-throughput separation of cancer cells from the WBCs

Deterministic Lateral Displacement (DLD) Analysis Tool Utilizing Machine Learning towards High-Throughput Separation

Deterministic lateral displacement (DLD) is a microfluidic method for the continuous separation of particles based on their size. There is growing interest in using DLD for harvesting circulating tumor cells from blood for further assays due to its low cost and robustness. While DLD is a powerful tool and development of high-throughput DLD separation devices holds great promise in cancer diagnostics and therapeutics, much of the experimental data analysis in DLD research still relies on error-prone and time-consuming manual processes. There is a strong need to automate data analysis in microfluidic devices to reduce human errors and the manual processing time. In this work, a reliable particle detection method is developed as the basis for the DLD separation analysis. Python and its available packages are used for machine vision techniques, along with existing identification methods and machine learning models. Three machine learning techniques are implemented and compared in the determination of the DLD separation mode. The program provides a significant reduction in video analysis time in DLD separation, achieving an overall particle detection accuracy of 97.86% with an average computation time of 25.274 s

Drag-based aerodynamic braking system for the Hyperloop: a numerical study

The Hyperloop promises to revolutionize the transport infrastructure of the 21st century by reducing travel time and allowing people to reach transonic speed on land. It carries with it the hope of a sustainable transportation system during an era of global energy crisis. Overall passenger safety in a high-speed pod necessitates a reliable braking system. This paper introduces the possibility of utilizing aerodynamic drag in the Hyperloop, anticipated to operate at high Mach and low Reynolds flow regime, to attenuate the speed of the pod. Numerical analysis was conducted to investigate the effect of incorporating an aerodynamic brake at different pod velocities (100, 135, and 150 m/s) and deployment angles (30°, 45°, 60°, and 90°). A detailed comparison between the proposed aerodynamic braking system (AeBS) and existing braking systems for the Hyperloop has been presented in this paper. The results demonstrate an increase in drag value of the pod by 3.4 times using a single 0.15 m2 brake plate. When the brake plate was fully deployed at a pod velocity in excess of 112 m/s, the aerodynamic drag-based braking systems was shown to be more effective than the contemporary eddy current braking system.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Neovaginoplasty using sigmoid colon flap technique

Background and objectives: Vaginoplasty is a procedure for the reconstruction of vaginal canal. Various surgical techniques have been described for vaginal reconstruction with variable success. The aim of this study was to assess the use of sigmoid colon in vaginal reconstruction of patients with disorders of sex development. Methods: Eleven patients were included in this study from January 2009 to December 2016. All patients underwent karyotyping, pelvi-abdominal ultrasonography, endocrine and psychiatric assessment. Sigmoid neo-vaginoplasty was the procedure chosen for all the cases. Surgical and functional outcomes were assessed post-operatively over a period of 6 month to 6 years. Results: The preoperative diagnosis included 9 cases of aplasia of the Mullerian ducts or Mayer-Rokitansky-Küster-Hauser syndrome (MRKH), 1 androgen insensitivity syndrome (AIS) and 1 pseudohermaphrodite case. The mean age of the study population was 22.5 years (range 15-30 yrs). No intra-operative or early postoperative complications occurred. The mean vaginal length achieved was 13.0 cm (range 10.5 – 15 cm). Long term follow-up showed introital stenosis in 2 cases (17%) which resolved well to vaginal dilatation. One patient had pelvic abscess and treated by surgery. Sexual satisfaction was achieved in 10 cases, as 1 case was unmarried. Conclusion: For patients with disorders of sex development of various etiologies, sigmoid vaginoplasty is the preferred technique for vaginal reconstruction. It is a safe technique and provides the patient with a cosmetic neovagina of adequate caliber with satisfactory functional outcome. IMC J Med Sci 2018; 12(1): 27-3

Energy analysis of a solar driven vaccine refrigerator using environment-friendly refrigerants for off-grid locations

10.1016/j.ecmx.2021.100095Energy Conversion and Management: X1110009