Chapter 7 Transdermal Microfluidic Continuous Monitoring Systems David D. Cunningham, David D. Cunningham Abbott Laboratories, Abbott Park, IL, USASearch for more papers by this author David D. Cunningham, David D. Cunningham Abbott Laboratories, Abbott Park, IL, USASearch for more papers by this author Book Editor(s):David D. Cunningham, David D. Cunningham Abbott Laboratories, Abbott Park, IL, USASearch for more papers by this authorJulie A. Stenken, Julie A. Stenken Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR, USASearch for more papers by this author First published: 23 November 2009 https://doi.org/10.1002/9780470567319.ch7Citations: 2 Series Editor(s): J. D. Winefordner, J. D. WinefordnerSearch for more papers by this author AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary This chapter contains sections titled: Introduction Reverse Iontophoresis-Based Systems Ultrasound-Based Systems Ablation-Based Systems Microneedle-Based Systems Other Methods of Accessing Interstitial Fluid Conclusions and Future Outlook References Citing Literature In Vivo Glucose Sensing, Volume 174 RelatedInformation

Technology assessment involves systematically gathering and weighing a wide variety of information in order to identify commercially viable opportunities. Small entrepreneurial companies and universities generate much of the new technology. A process often followed by large companies to find and evaluate new technologies is described with the aim of facilitating interactions between the holders of new technology and large companies. Technology assessment generally follows the steps of obtaining new leads, screening leads, evaluating preliminary technology, performing due diligence, and negotiating a deal. The importance of a clear business strategy and proper consideration of intellectual property are emphasized.

Attachment of a small, medical device to the human body for an extended period of time in an ambulatory setting requires the careful consideration of the physical form of the device and the physiological constraints limiting the time a device will stay on the skin. Factors such as the size of the device, the area of the device available for attachment to the skin, and the occlusive nature of the materials in the device are likely to affect adhesion. Here, plastic acrylic disks, 25 mm in diameter, containing a crisscross pattern of air-filled channels were tested on the forearm and abdomen using a moderately aggressive, unsupported, pressure-sensitive transfer adhesive in a pilot human clinical study. After vigorous exercise, droplets of moisture were observed in the channels followed by evaporation of the droplets over time. Disks without channels remained attached to the skin for about a day and a half, while disks containing 450 μm deep channels remained on the skin about three times longer. Little difference was found when the channel-to-channel spacing was increased from 1.3 to 1.6 mm, however 230 μm deep channels were less effective than 450 μm deep channels. Overall, the moisture vapor transport channels appear capable of reducing the moisture content of the outermost stratum corneum layer of the skin, increasing the strength of the stratum corneum, and increasing the time a device remains attached to the skin. The median trial-to-trial relative standard deviation of 45% observed in the pilot study can be used to design appropriately powered studies for the comparison of different device designs.

Sorbitol dehydrogenase (hSDH) and aldose reductase form the polyol pathway that interconverts glucose and fructose. Redox changes from overproduction of the coenzyme NADH by SDH may play a role in diabetes-induced dysfunction in sensitive tissues, making SDH a therapeutic target for diabetic complications. We have purified and determined the crystal structures of human SDH alone, SDH with NAD(+), and SDH with NADH and an inhibitor that is competitive with fructose. hSDH is a tetramer of identical, catalytically active subunits. In the apo and NAD(+) complex, the catalytic zinc is coordinated by His69, Cys44, Glu70, and a water molecule. The inhibitor coordinates the zinc through an oxygen and a nitrogen atom with the concomitant dissociation of Glu70. The inhibitor forms hydrophobic interactions to NADH and likely sterically occludes substrate binding. The structure of the inhibitor complex provides a framework for developing more potent inhibitors of hSDH.

Newer clinical chemical instruments and devices feature advanced sample handling fluidic systems. This review presents descriptions of the technologies utilized in high throughput automated systems, remote point-of-care analyzers, non-automated test strip systems, blood glucose testing products, and automated nucleic acid based assay systems. The physical processes involved in the fluidic systems include simple diffusion, capillary action, positive pressure displacement, vacuum, magnetic forces, centrifugal motion, and electrochemical processes. Key issues and performance parameters are highlighted. Finally, the state-of-the-art in miniaturized fluidic components is presented with a summary of capillary electrophoresis chips and their application to clinically relevant targets.