An integrated microfluidic chip for chromosome enumeration using fluorescence in situ hybridization

Fluorescence in-situ hybridization (FISH) is more sensitive than classical cytogenetics for detecting cryptic chromosomal abnormalities. H; however, the protocol complexity, high reagent cost and long hybridization time associated with a typical interphase FISH analysis have slowed its utilization in a clinical setting. For various cancers, such as multiple myeloma, the lack of a cost-effective and informative diagnostic method has compromised the quality of life for patients. Here, wWe present the first demonstration of a microchip-based FISH protocol for the analysis of chromosomal abnormalities in multiple myeloma cells to address this issue. The developed microfluidic arrays allow several chromosomal abnormalities associated with multiple myeloma to be detected with a 10 fold higher throughput and 1/10th the reagent consumption of the traditional slide based FISH. These benefits have resulted in the arrays being actively used in a clinical laboratory. We examined two methods of enhancing the hybridization, using mechanical and electrokinetic agitation. Both methods yielded improvements in the hybridization efficiency and warrant further optimization studies. Ultimately, we established a novel method of performing interphase FISH on a microchip in hours whereas the conventional protocol requires days. We believe that additional optimization studies would improve the hybridization enhancement even further, reducing the analysis time to less than one hour and making point of care FISH analysis a possibility

An Energy Efficient Thermally Regulated Optical Spectroscopy Cell for Lab-on-Chip Devices: Applied to Nitrate Detection

Reagent-based colorimetric analyzers often heat the fluid under analysis for improved reaction kinetics, whilst also aiming to minimize energy use per measurement. Here, a novel method of conserving heat energy on such microfluidic systems is presented. Our design reduces heat transfer to the environment by surrounding the heated optical cell on four sides with integral air pockets, thereby realizing an insulated and suspended bridge structure. Our design was simulated in COMSOL Multiphysics and verified in a polymethyl methacrylate (PMMA) device. We evaluate the effectiveness of the insulated design by comparing it to a non-insulated cell. For temperatures up to 55 °C, the average power consumption was reduced by 49.3% in the simulation and 40.2% in the experiment. The designs were then characterized with the vanadium and Griess reagent assay for nitrate at 35 °C. Nitrate concentrations from 0.25 µM to 50 µM were tested and yielded the expected linear relationship with a limit of detection of 20 nM. We show a reduction in energy consumption from 195 J to 119 J per 10 min measurement using only 4 µL of fluid. Efficient heating on-chip will have broad applicability to numerous colorimetric assays

Nanomolar detection with high sensitivity microfluidic absorption cells manufactured in tinted PMMA for chemical analysis

We describe a novel, cost effective and simple technique for the manufacture of high sensitivity absorption cells for microfluidic analytical systems. The cells are made from tinted polymethyl methacrylate (PMMA) in which microfluidic channels are fabricated. Two windows (typically 250 ?m thick, resulting in little optical power loss) are formed at either end of the channel through which light is coupled. Unwanted stray light from the emitter passes through a greater thickness of the tinted substrate (typically the length of the cell) and is preferentially absorbed. In effect, this creates a pin-hole configuration over the length of the absorption cell, providing improved performances (sensitivity, S/N ratios, baseline noise and limit of detection) when used as an absorption cell compared to clear substrates. The method is used to achieve a LOD of 20 nM with a colourimetric iron assay and a LOD of 0.22 milli-absorption units with a pH assay

Lab-on-Chip Measurement of Nitrate and Nitrite for In Situ Analysis of Natural Waters

Microfluidic technology permits the miniaturization of chemical analytical methods that are traditionally undertaken using benchtop equipment in the laboratory environment. When applied to environmental monitoring, these “lab-on-chip” systems could allow high-performance chemical analysis methods to be performed in situ over distributed sensor networks with large numbers of measurement nodes. Here we present the first of a new generation of microfluidic chemical analysis systems with sufficient analytical performance and robustness for deployment in natural waters. The system detects nitrate and nitrite (up to 350 μM, 21.7 mg/L as NO3 −) with a limit of detection (LOD) of 0.025 μM for nitrate (0.0016 mg/L as NO3 −) and 0.02 μM for nitrite (0.00092 mg/L as NO2 −). This performance is suitable for almost all natural waters (apart from the oligotrophic open ocean), and the device was deployed in an estuarine environment (Southampton Water) to monitor nitrate+nitrite concentrations in waters of varying salinity. The system was able to track changes in the nitrate−salinity relationship of estuarine waters due to increased river flow after a period of high rainfall. Laboratory characterization and deployment data are presented, demonstrating the ability of the system to acquire data with high temporal resolution

An automated microfluidic colourimetric sensor applied in situ to determine nitrite concentration

A stand-alone sensor system with integrated sub-systems is demonstrated. The system is portable and capable of in situ reagent-based nutrient analysis. The system is based on a low cost optical detection method, together with an automated microfluidic delivery system that is able to detect nitrite with a limit of detection (LOD) of 15 nM. The sensor was operated in situ at Southampton Dockhead for 57 h (December 2010) and 375 measurements were taken

Optical Measurement of Saturates, Aromatics, Resins, And Asphaltenes in Crude Oil

We describe a novel apparatus and method for rapidly separating and measuring four subfractions of crude oil: saturates, aromatics, resins, and asphaltenes (SARA). This work is an extension of our previous work on the microfluidic measurement of asphaltene content, where a microfluidic technique was used to rapidly separate asphaltenes from crude oil for indirect optical measurement. Here, we extend the measurement by adding column chromatography to fractionate the deasphalted oil into saturate, aromatic, and resin fractions. Saturates are measured by refractive index, whereas the aromatics, resins, and asphaltenes are measured by ultraviolet–visible (UV–vis) absorbance. We evaluate 15 samples from various geographical origins to determine appropriate optical-to-gravimetric response factors. The response factors are then used to enable a seamlessly automated SARA measurement technique. When the 15 samples are run through the automated procedure, the optical-to-gravimetric root-mean-square error (RMSE) values are ±3.8 wt % for saturates, ±2.7 wt % for aromatics, ±2.3 wt % for resins, and ±1.2 wt % for asphaltenesabsolute errors. The final microfluidic SARA technique exhibited excellent reproducibility; the measurements were within ±0.8 wt % for saturates, aromatics, and resins and within ±0.2 wt % for asphaltenes. Further, the technique reduced SARA experimental times from 2 days to 4 h for topped samples while greatly reducing the need for manual labor