We describe the translation of a cloth-based hybridization array system (CHAS), a colorimetric DNA detection method that is used by food inspection laboratories for colony screening of pathogenic agents, onto a microfluidic chip format. We also introduce an articulated centrifugal platform with a novel fluid manipulation concept based on changes in the orientation of the chip with respect to the centrifugal force field to time the passage of multiple components required for the process. The platform features two movable and motorized carriers that can be reoriented on demand between 0 and 360° during stage rotation. Articulation of the chip can be used to trigger on-the-fly fluid dispensing through independently addressable siphon structures or to relocate solutions against the centrifugal force field, making them newly accessible for downstream transfer. With the microfluidic CHAS, we achieved significant reduction in the size of the cloth substrate as well as the volume of reagents and wash solutions. Both the chip design and the operational protocol were optimized to perform the entire process in a reliable, fully automated fashion. A demonstration with PCR-amplified genomic DNA confirms on-chip detection and identification of Escherichia coli O157:H7 from colony isolates in a colorimetric multiplex assay using rfbO157, fliCH7, vt1, and vt2 genes.

We have investigated high-frequency ultrasound generated by single laser pulses in thin (50μm) aluminum foils as a function of the laser fluence. Laser-pulse durations of 80fs and 270ps were used to compare the ultrasound generated in two very different regimes: thermoelastic and ablation. The measured rear-surface displacement induced by the ultrasound pulse is similar after 50-μm propagation through the foils for the two laser-pulse durations in the fluence range of 0.1–0.7J∕cm2. For fluences greater than the ablation threshold (0.25 and 0.63J∕cm2 for the 80-fs and 270-ps pulses, respectively), the ultrasound amplitude generated by the 270-ps laser pulse is increased significantly due to absorption of laser energy by the ablating plasma. This is not observed for the 80-fs laser pulse since ablation is produced well after the laser-pulse irradiation of the target. The measured surface displacement as a function of laser fluence is compared to the calculations of a one-dimensional fluid code for both laser-pulse durations. The model calculations agree in many ways with the experimental results, but some discrepancies are observed.

Thick film (90µm) piezoelectric ceramic ultrasonic transducers (UTs) have been successfully deposited on a barrel and a mold insert of a micromolding machine by a sol-gel spray technique. The ball-milled bismuth titanate fine powders are dispersed into PZT solution to achieve the gel. The gel is then sprayed onto the substrate at room temperature. The films with desired thickness have been obtained through multilayer coating approach. Piezoelectricity is achieved using a corona discharge poling method. These UTs can operate at more than 500°C. The center frequency of ultrasound generated is 13MHz and 6dB bandwidth is 13MHz. In the pulse/echo mode the ultrasonic signals have a signal to noise ratio of more than 30dB. The ability of these UTs to monitor the polymer properties in real-time at the barrel and the mold insert of the micro-molding machine during processing is demonstrated.

The goal of this project was to demonstrate the feasibility to measure the mechanical properties of low carbon steel sheets on the production line using laser ultrasound. Three types of steels were selected: ultra low carbon (ULC), low carbon (LC), and high strength low alloy (HSLA). The mechanical properties under study were yield strength (YS), ultimate tensile strength (TS), tota1 elongation (TE), uniform elongation (UE), strain hardening exponent (n), and the two plastic strain ratio parameters, F and Ar . In addition, the ultrasonic techniques provided information on crystallographic texture, grain size, and sheet thickness. The measurement target accuracy for the various mechanical properties were (the "*" refers to one standard deviation):not specified.The in-plane average plastic strain ratio was measured to within k 0.04 to * 0.09 depending whether all grades from all companies were considered together or individually.Grain size measurement accuracy varied between f 2 % and f 14 % depending on grade.Sheet thickness could be measured to within f 4 pm when all grades were considered together, although thicknesses measured within a single grade and thickness, variations of * 1 pm could easily be detected.A prototype aimed at validating the technology on the production line was installed at the #1 Inspection line at LTV, Cleveland. Overall, the prototype's performance was as good online as in the laboratory. Sheet vibrations as well as ambient mechanical and electrical noise did not adversely affect the measurement. Optical alignment was preserved over time scales of about two weeks, i.e. between two successive trips to the plant. And data acquisition and analysis were done in real time. Thus, the project reached its goal to demonstrate that mechanical properties can be measured online using laser-ultrasonics. (RDP Standard Form, Form 298)Sponsor