Microfluidics is used in many applications ranging from chemistry, medicine, biology and biomedical research, and the ability to measure pH values in-situ is an important parameter for creating and monitoring environments within a microfluidic chip for many such applications. We present a portable, optical fibre-based sensor for monitoring the pH based on the fluorescent intensity change of an acrylamidofluorescein dye, immobilized on the tip of a multimode optical fibre, and its performance is evaluated in-situ in a microfluidic channel. The sensor showed a sigmoid response over the pH range of 6.0–8.5, with a maximum sensitivity of 0.2/pH in the mid-range at pH 7.5. Following its evaluation, the sensor developed was used in a single microfluidic PDMS channel and its response was monitored for various flow rates within the channel. The results thus obtained showed that the sensor is sufficiently robust and well-suited to be used for measuring the pH value of the flowing liquid in the microchannel, allowing it to be used for a number of practical applications in ‘lab-on-a-chip’ applications where microfluidics are used. A key feature of the sensor is its simplicity and the ease of integrating the sensor with the microfluidic channel being probed.

The detection of soluble proteins in biological fluids, as a form of liquid biopsy, is a promising tool for cancer diagnosis and prognosis, as it is less invasive than traditional diagnostic methods. CD44 is one of the most recognized markers of cancer stem cells, a small subset of cells responsible for cancer initiation, progression, and metastasis. Given the importance of CD44 as a cancer biomarker, several review articles explore the diagnostic and therapeutic value of cell-surface CD44. In addition to being a membrane-anchored protein, CD44 is also shed from the cell surface and can be found in various biological fluids. However, the role of soluble CD44 in cancer has not been comprehensively discussed in recent reviews. Measuring soluble CD44 in various biological liquids can provide a practical and valuable tool for cancer diagnosis and treatment monitoring. Therefore, this review comprehensively discusses the role of soluble CD44 as a marker in various cancer types, including serum, saliva, urine, and other fluids. In particular, its role as an early cancer biomarker and as a predictive and prognostic biomarker in several cancers is discussed. This work also provides an overview of a wide range of analytical techniques used to detect soluble CD44. The value of cells expressing CD44 versus soluble CD44 as a biomarker is also compared. The review concludes with a perspective on future directions, emphasizing the shift toward non-invasive analytical methods and the need for standardization of detection, including multiple biomarkers during evaluation, to improve the accuracy of cancer diagnosis.

Breast cancer remains a major cause of cancer-related mortality in women, and its substantial molecular heterogeneity highlights the need for methods capable of characterizing tumor cells at the cellular level. CD44, a transmembrane glycoprotein associated with breast cancer progression, metastasis, and cancer stem-like phenotypes, is a promising biomarker for selective recognition of aggressive, basal-like cell populations. However, conventional approaches to evaluating CD44 expression including immunohistochemistry, immunofluorescence, and flow cytometry require labeling and multi-step sample preparation. In this work, a gold-coated, polydimethylsiloxane (PDMS)-based extrinsic semi-distributed interferometric (SDI) optical fiber biosensor functionalized with anti-CD44 antibodies was developed for label-free, selective detection of CD44-expressing HCC1806 breast cancer cells. The functionalized sensor exhibited a concentration-dependent response with a limit of detection (LoD) of 2.51 cells/mL, while the antibody-free control sensor exposed to HCC1806 cells and the anti-CD44-functionalized sensor exposed to CD44-low HEK293 cells showed only minimal responses, supporting selective detection under the tested conditions. These results support the potential of the antibody-functionalized ESDI platform for label-free detection of CD44-expressing cells, providing a groundwork for its validation in clinical samples as a step toward tumor-cell diagnostics.

In the realm of supersonic design, obtaining data for numerous supersonic configurations amidst intricate flow conditions proves time-consuming due to the excessive costs associated with high-fidelity computational demands. Running iterative simulations over an extended period is often impractical or entails substantial expenses. This inherent challenge necessitates the adoption of low-order potential solvers with reasonable accuracy to generate datasets. In support of this objective, This study addresses the high computational costs of obtaining data for supersonic configurations by developing a low-order solver that combines the Taylor-Maccoll hypervelocity method (TMHM) with the supersonic vortex lattice method. This approach aims to provide accurate drag predictions in supersonic flows while minimizing computational demands. By integrating TMHM to calculate wave drag and skin friction drag and enhancing the vortex lattice method to handle shockwave impacts through panel matching, the solver achieves improved accuracy in lift and drag computations. Validation against experimental data shows a 20% reduction in drag prediction error compared to traditional vortex lattice methods, with a 2.01% error for low-shock angles. The method achieves accuracy rates between 90% and 95% across various configurations, including a 90% accuracy for delta wings, 85% for positive dihedral wings, and 95% for large sweptback angle designs, as confirmed by comparisons with high-fidelity CFD data.