Arthur J. Helmicki

An integrated microfluidic biochemical detection system for protein analysis with magnetic bead-based sampling capabilities

This paper presents the development and characterization of an integrated microfluidic biochemical detection system for fast and low-volume immunoassays using magnetic beads, which are used as both immobilization surfaces and bio-molecule carriers. Microfluidic components have been developed and integrated to construct a microfluidic biochemical detection system. Magnetic bead-based immunoassay, as a typical example of biochemical detection and analysis, has been successfully performed on the integrated microfluidic biochemical analysis system that includes a surface-mounted biofilter and electrochemical sensor on a glass microfluidic motherboard. Total time required for an immunoassay was less than 20 min including sample incubation time, and sample volume wasted was less than 50 microl during five repeated assays. Fast and low-volume biochemical analysis has been successfully achieved with the developed biofilter and immunosensor, which is integrated to the microfluidic system. Such a magnetic bead-based biochemical detection system, described in this paper, can be applied to protein analysis systems.

Development and Characterization of Microfluidic Devices and Systems for Magnetic Bead-Based Biochemical Detection

This paper presents the development and characterization of a generic microfluidic system for magnetic bead-based biochemical detection. Microfluidic and electrochemical detection devices such as microvalves, flow sensors, biofilters, and immunosensors have been successfully developed and individually characterized in this work. Magnetically driven microvalves, pulsed-mode microflow sensors, magnetic particle separators as biofilters, and electrochemical immunosensors have been sep-arately fabricated and tested. The fabricated microfluidic components have been surface-mounted on the microfluidic motherboard for fully integrated microfluidic biochemical detection system. A magnetic bio-bead approach has been adopted for both sampling and manipulating target biological molecules. Magnetic beads were used as both substrate of antibodies and carriers of target antigens for magnetic bead-based immunoassay, which was chosen as a proof-of-concept for the generic microfluidic bio-chemical detection system. The microfluidic and electrochemical immunosensing experiment results obtained from this work have shown that the biochemical sensing capability of the complete microfluidic subsystem is suitable for portable biochemical detection of bio-molecules. The methodology and system, which has been developed in this work, can be extended to generic bio-molecule detection and analysis systems by replacing antibody/antigen with appropriate bio receptors/reagents such as DNA fragments or oligonucleotides for application towards DNA analysis and/or high throughput protein analysis.

The Application of the Ecological Interface Design Approach to Neonatal Intensive Care Medicine

Ecological interface design techniques were used to first model and then develop an interface to help clinicians assess tissue oxygenation in a neonatal intensive care unit. Several challenges were encountered during this work. The abstraction hierarchy model structure that was used has limitations in this environment. The first limitation concerned the depth of knowledge that was available. Tissue oxygenation is a complex, and not totally understood process. Furthermore, it is truly distributed in nature. Both these limit the level of detail that could be included in the system model. Second, in this environment the sensor suite is very limited and is defined a-priori. Therefore, many of the variables that were identified as important in the abstraction hierarchy model are impossible to measure. Despite these limitations, the interface that resulted from the abstraction hierarchy model compared favorably to the existing interface in a simulated clinical environment.

Subjective and Objective Evaluations of Bridge Damage

A decommissioned, 40+-year-old reinforced concrete deck on a steel girder bridge was subjected to a series of induced damages, nondestructive field tests, and visual evaluations to compare objective and subjective methods of bridge-condition assessment. Prior subjective evaluations of bridge condition often produced highly variable results. For example, inspectors with different backgrounds and field experience disagreed on how severely certain forms of deterioration and damage influenced bridge behavior and safety so, consequently, different assessments of bridge condition were generated. Furthermore, a load rating of the “as-is” state of the bridge (e.g., the state before any induced damages), according to current Ohio Department of Transportation procedures, indicated that the bridge could only support truckloads of 227 804 N (51,192 lbf). However, the objective data acquired during nondestructive field testing of the bridge, which was subjected to truckloads of 282 130 N (63,400 lbf), revealed maximum superstructure deflections and live-load stresses of 0.190 cm (0.075 in.) and 15 985 kPa (2,320 psi)—values well within AASHTO limits. These values also imply that the bridge can support loads much greater than those indicated in the load rating. Comparing subjective and objective assessments for the induced damage scenarios yielded similar results. Essentially, data revealed that subjective methods of bridge evaluation and assessment were unable to properly characterize intrinsic bridge mechanisms and the influence that such mechanisms have on bridge behavior. Condition assessment of a typical reinforced concrete deck on a steel girder bridge should therefore include objective evaluations of bridge condition and behavior.

Performance of Five-Span Steel Bridge with Fiber-Reinforced Polymer Composite Deck Panels

To better understand the performance of bridges with fiber-reinforced polymer (FRP) composite decks, the short-term and long-term responses of a 207-m, five-span bridge retrofitted with four different FRP panel systems were monitored through controlled truck load and modal tests at various stages and through long-term monitoring of key load-transfer mechanisms and panel responses. The overall aspects of the panel systems, connection details, construction techniques, and experimental program are presented followed by presentation of the measured responses. Key design issues (impact factors, girder distribution factors, level of composite action, and overall structural stiffness) for FRP and reinforced concrete decks are evaluated and compared against published design provisions. Performance of panel-to-panel connections and panel-to-girder connections is also discussed.

An integrated microfluidic biochemical detection system with magnetic bead-based sampling and analysis capabilities

This paper presents the development and characterization of an integrated microfluidic biochemical detection system for fast and low volume immunoassays using magnetic beads, which are used as both immobilization surfaces and bio-molecule carriers. Magnetic bead-based immunoassay, as a typical example of biochemical detection and analysis, has been successfully performed on the integrated microfluidic biochemical analysis system that includes a surface-mounted biofilter and immunosensor on a glass microfluidic motherboard. Total time required for full immunoassay was less than 20 minutes including sample incubation time and sample volume wasted was less than 50 /spl mu/l during five repeated assays. Fast and low volume biochemical analysis has been successfully achieved with the developed biofilter and immunosensor, which is integrated to microfluidic system.

Cable-Stayed Bridges: Case Study for Ambient Vibration-Based Cable Tension Estimation

A cable-stayed bridge recently constructed by the Ohio Department of Transportation incorporates measures put forth by a Federal Highway Administration study to mitigate stay motion. In following recent trends, the stays at this bridge are built without the use of grout for the purposes of inspection and, if necessary, replacement. Several experiments were performed to determine the viability of using traditional vibration techniques, which assume an integral sheath, to estimate cable tension with this new configuration.

Development of a high permeability cored transintegumental power transformer.

Circulatory support devices require 10-20 W. Currently, several devices are under development for the transmission of this power via transcutaneous transformers, with the secondary implanted subcutaneously and the primary worn externally. Because these devices are air cored, they have relatively large, bulky external appliances, poor coil to coil coupling, and result in significant stray fields passing through adjacent tissues. This article reports on the engineering design of a novel, high permeability cored transformer implanted in a transenteric configuration using an isolated intestinal pouch. Such an approach offers greater energy transmission efficiency, less heat dissipation, less stray electromagnetic energy, and greatly reduced device size. Two competing designs using this concept have been developed and tested. Each consists of the transformer, together with power interface electronics, forming a direct current (DC)/DC resonant converter. Operating frequencies are 90.2 and 14.7 kHz, respectively, with primary/secondary turns ratios of 10/10 and 11/14, respectively. In addition, data interface electronics allows communication across the transformer of up to four signals at a per channel sample rate of 10 Hz. Both designs are able to continuously transmit 25 W at an output level of 12 Vdc into a 5.8 omega load. Calorimetry tests indicate DC to DC efficiencies greater than 75% and coil to coil efficiencies greater than 96%. Total package size for the implantable portion of each device (including sensor internal interface electronics) is less than 40 ml, with a weight weight of less than 100 g. The results of short-term implantation studies have been favorable. Long-term implantation studies currently are under way.

Abnormal behavior detection in the Jeremiah Morrow Bridge based on the long term measurement data patterns

Calibration of a finite element model based on measurement-data for complex structures is usually costly and sometimes not applicable. In this article, a methodology for detecting abnormal behavior including slow aging degradations of a structure solely based on historical patterns of the measurement data will be introduced. In the first step, principal components of the truck load test measurement data - that is centered and scaled - are calculated. In the second step, unsupervised classification is applied to the score data that is regenerated based on the major principal components. The same algorithm is applied to the measurement data of the bridge response to the sharp temperature change as well. Finally, the specified algorithm is applied separately to the collected static data from the Jeremiah Morrow Bridge (more than four years) using the calculated truck load test principal components. The optimized clustering model detected the outliers that are caused by heavy truck loads; clustering result is detailed. In summary, a simple data model that is able to find any known data signature such as truck load test in the daily measurement data is proposed. The proposed method is part of an ongoing effort in University of Cincinnati Infrastructure Institute to use the correlation between collected readings from different members of a bridge in order to interpret abnormal trend changes in the measurement data.

Development and Characterization of a Generic Microfluidic Subsystem toward Portable Biochemical Detection

This paper presents the development of a generic microfluidic system toward portable biochemical detection. Microfluidic and electrochemical detection devices such as microvalves, flow sensors, biofilters, and immunosensors have been successfully developed and characterized in this work. A magnetic bio-bead approach has been adopted for both sampling and manipulating target biological molecules. The microfluidic and electrochemical immunosensing experiment results obtained from this work have shown that the biochemical sensing capability of the complete microfluidic subsystem is suitable for portable biochemical detection of bio-molecules.