The global need for accurate and efficient cancer cell detection in biomedicine and clinical diagnosis has driven extensive research and technological development in the field. Precision, high-throughput, non-invasive separation, detection, and classification of individual cells are critical requirements for successful technology. Lab-on-a-chip devices offer enormous potential for solving biological and medical problems and have become a priority research area for microanalysis and manipulating cells. This paper reviews recent developments in the detection of cancer cells using the microfluidics-based lab-on-a-chip method, focusing on describing and explaining techniques that use optical phenomena and a plethora of probes for sensing, amplification, and immobilization. The paper describes how optics are applied in each experimental method, highlighting their advantages and disadvantages. The discussion includes a summary of current challenges and prospects for cancer diagnosis.

Hybrid inorganic–organic Nafion membranes modified with metal oxides (typically TiO ₂ , ZrO ₂ , WO ₃ ) are a good alternative for fuel cell applications. However, one of their main limitations is associated with their relative low proton conductivity at temperatures above 80 °C. In this work, we overcome this issue using HfO ₂ as a filler. HfO ₂ was prepared by a sol–gel method, and it was compared with a recast Nafion membrane (named as recast). Deconvolved XPS spectra confirmed the presence of hafnia, while EDS analysis was used to determine its weight content resulting in a 1.88 wt%. FT-IR ATR experiments indicated that the HfO ₂ hybrid membrane possess a higher capability to retain water than the recast. Thus, the water uptake, swelling degree, conductivity tests and fuel cell evaluations were performed. The water uptake analysis revealed that the hybrid membrane presented a higher retention percentage at 100 °C (61%) than recast (29%). This improvement enabled a higher ionic conductivity at 80 °C and 100 °C. The hybrid membrane displayed a higher conductivity at 100 °C than the recast membrane (112 versus 82 mS cm ⁻¹ ), increasing the cell performance to 0.36 W cm ⁻² ; being this performance almost two-fold higher to that obtained for the recast membrane. In summary, herein we demonstrated that HfO ₂ can be considered as an excellent substitute to conventional fillers.

Microfluidic fuel cells (μFFC) are emerging as a promising solution for small-scale power demands. The T-shaped architecture of the μFFC promotes a laminar flow regimen between the catholyte and anolyte streams excluding the use of a membrane, this property allows a simplest design and the use of several micromachining techniques based on a lab-on-chip technologies. This work presents a combination of new materials and low cost fabrication processes to develop a light, small, flexible and environmental friendly device able to supply the energy demand of some portable devices. Well-defined and homogeneous Pd nanocubes which exhibited the (100) preferential crystallographic plane were supported on Vulcan carbon and used as anodic electrocatalyst in a novel and compact design of a SU-8 μFFC feeded with formic acid as fuel. The SU-8 photoresist properties and the organic microelectronic technology were important factors to reduce the dimensions of the μFFC structure. The results obtained from polarization and power density curves exhibited the highest power density (8.3 mW cm−2) reported in literature for direct formic acid μFFCs.

This work presents the design, fabrication, and testing of a circular split ring resonator (Cir-SRR) with an embedded interdigital capacitor (IDC) for emerging contaminant detection. The IDC attached to the outer ring gap of the Cir-SRR concentrates the electric field and improves the sensitivity of the resonator. According to measurements, the IDC/Cir-SRR resonates at 1.77 GHz and achieves a quality factor Q of 295. The simulation reported a hot spot of 115.9204 dBV/m in the IDC detection zone. The resonant frequency shifts approximately 400 MHz when the liquid sample changes from water to ethanol. The sensitivity was studied using ethanol in deionized water. An average sensitivity of 1.53% was achieved in the relative permittivity range of 18–79. Triclosan and glyphosate were selected as emerging contaminants and were tested by dissolving them in a 50% ethanol-water mixture and water, respectively. Linear relationships between the S₂₁ transmission parameter and concentration were found in the selected ranges of 0–50 μg/mL and 0–35 μg/mL for triclosan and glyphosate, respectively. A sensitivity of 6.87×10^-2 dB/(μg/mL) and a limit of detection (LOD) of 1.83 μg/mL were obtained with glyphosate solutions. In contrast, the values of 1.47×10^-2 dB/(μg/mL) and 1.18 μg/mL were obtained with triclosan solutions. The results suggest that this technology offers a viable approach for the rapid detection of emerging water contaminants.