A rapid, low cost, accurate point-of-care (POC) device to detect influenza virus is needed for effective treatment and control of both seasonal and pandemic strains. We developed a single-use microfluidic chip that integrates solid phase extraction (SPE) and molecular amplification via a reverse transcription polymerase chain reaction (RT-PCR) to amplify influenza virus type A RNA. We demonstrated the ability of the chip to amplify influenza A RNA in human nasopharyngeal aspirate (NPA) and nasopharyngeal swab (NPS) specimens collected at two clinical sites from 2008–2010. The microfluidic test was dramatically more sensitive than two currently used rapid immunoassays and had high specificity that was essentially equivalent to the rapid assays and direct fluorescent antigen (DFA) testing. We report 96% (CI 89%,99%) sensitivity and 100% (CI 95%,100%) specificity compared to conventional (bench top) RT-PCR based on the testing of n = 146 specimens (positive predictive value = 100% (CI 94%,100%) and negative predictive value = 96% (CI 88%,98%) ). These results compare well with DFA performed on samples taken during the same time period (98% (CI 91%,100%) sensitivity and 96% (CI 86%,99%) specificity compared to our gold standard testing). Rapid immunoassay tests on samples taken during the enrollment period were less reliable (49% (CI 38%,61%) sensitivity and 98% (CI 98%,100%) specificity). The microfluidic test extracted and amplified influenza A RNA directly from clinical specimens with viral loads down to 10 3 copies/ml in 3 h or less. The new test represents a major improvement over viral culture in terms of turn around time, over rapid immunoassay tests in terms of sensitivity, and over bench top RT-PCR and DFA in terms of ease of use and portability.

A continuous flow polymerase chain reaction (CF-PCR) device comprises a single fluidic channel that is heated differentially to create spatial temperature variations such that a sample flowing through it experiences the thermal cycling required to induce amplification. This type of device can provide an effective means to detect the presence of a small amount of nucleic acid in very small sample volumes. CF-PCR is attractive for global health applications due to its less stringent requirements for temperature control than for other designs. For mass production of inexpensive CF-PCR devices, fabrication via thermoplastic molding will likely be necessary. Here we study the optimization of a PCR assay in a polymeric CF-PCR device. Three channel designs, with varying residence time ratios for the three PCR steps (denaturation, annealing, and extension), were modeled, built and tested. A standardized assay was run on the three different chips, and the PCR yields were compared. The temperature gradient profiles of the three designs and the residence times of simulated DNA molecules flowing through each temperature zone were predicted using computational methods. PCR performance predicted by simulation corresponded to experimental results. The effects of DNA template size and cycle time on PCR yield were also studied. The experiments and simulations presented here guided the CF-PCR chip design and provide a model for predicting the performance of new CF-PCR designs prior to actual chip manufacture, resulting in faster turn around time for new device and assay design. Taken together, this framework of combined simulation and experimental development has greatly reduced assay development time for CF-PCR in our lab.

A magnetic catalyst could be applied in a fluidized bed to improve the catalytic efficiency in the methanation and selective hydrogenation processes. Its distributions play an important role in accelerating the reactions. Electromagnetic tomography (EMT) provides an effective solution for online monitoring of the distribution of a magnetic catalyst. However, most of the EMT systems were developed to investigate the conductivity distribution. A novel EMT for the reconstruction of permeability distribution is presented in this paper. The coils, of which the sensitivity are related to frequency and coil size, were used as receivers in conventional EMT systems. In this paper, a tunneling magnetoresistance (TMR) sensor is applied to take the place of the coil. Compared with coils, the advantages of a TMR sensor on the frequency-independence and spatial resolution were investigated. A coil-TMR array was designed, in which the coil geometry was optimized and the TMR sensor was selected. The sensitivity matrix of the novel system was calculated by the perturbation method in a 3D simulation model. A FPGA-based system was designed. The reconstruction results of the magnetic catalyst validated the practicability of the permeability EMT based on TMR sensors.

Fast and effective diagnostics play an important role in controlling infectious disease by enabling effective patient management and treatment.

We fabricated a surface acoustic wave (SAW) NH 3 gas sensor based on a TiO 2 sensitive film. The TiO 2 film was deposited using a combined sol-gel and spin-coating technology. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that the film was porous and had good crystallinity. Fourier Transform infrared spectroscopy (FTIR) analysis revealed that there was a large amount of hydroxyl groups on the film, which can capture H 2 O molecules from the ambient environment. The sensor showed a positive response to NH 3 gas and the response increased significantly with increasing relative humidity. The positive response was found to be caused by the change in the elastic modulus of the sensitive film, which was induced by the condensation of the hydroxyl groups on the film catalyzed by NH 3 . The sensor also had a low detection limit of 1 ppm and excellent selectivity and stability to NH 3 gas.