Documents / Report
This Defense Intelligence Agency reference document, dated 31 March 2010 (DIA-08-1003-020), was one of a series of advanced technology reports produced in FY 2009 under the Advanced Aerospace Weapon System Applications (AAWSA) program. It surveys biosensors and BioMEMS, covering brain-implanted neuroelectrodes, drug-delivery pumps, implantable glucose sensors, brain-machine interfaces, retinal prostheses, microfluidic lab chips, NASA cell culture systems, and microcantilever sensors. It concludes that the field is expanding rapidly toward nanomechanical systems.
“The Advance”8 pages
UNCLASSIFIED/ i<F&R: &FFI@Itlrt 1!181!! 8HL'f An enzyme-gel is applied in a thin layer over a electrically biased metal electrode. An electrical current flows through the electrode when the hydrogen peroxide produced by the glucose reaction is decomposed and causes an electrical current to flow. If there is a fixed concentration of glucose present, a corresponding amount of peroxide will be produced, and this can be measured by the electrical current flow. The amount of peroxide measured is an indicator of the glucose concentration. The actual amount of analyte consumed by a small BioMEMS sensor is exceedingly small and has no significant effect on the local concentration. Figure 11 shows a MEMS implementation of a blood glucose sensor using this kind of approach (Advanced Biosensors Inc). The fine needle geometry is generally meant for insertion into tissue. This device is comprised of multiple independent small sensors and is actually a system of components that adds signal processing and interface electronics to allow its communication with insulin pumps for automated delivery of insulin based on patient need. Advanced BioSensors blood glucose sensor Flip chip assembly ASICs, power sources and circuit components Separate sensors, mount with electrical connections. add the biocompatible polymer, assemble the sensor patch. The sensor based on glucose oxidase reaction with blood plasma from capillaries in the dermis. biochemical coating - sensor 1n place 3 - 7 days Docking port for electronics assembly v,ith amplifier, ADC, vmeless transceiver. power source encrypted digital data to wristwatch-sized monitor/recorder module In future combine the CGMS with an insulin pump to produce a closed-loop system-an artificial pancreas. Figure 11. An Experimental MEMS Blood Glucose Sensor ,•·-..--. •••. .•• 1 rr long x 200 um •:,ice Glucose sensors based on electrical measurement of hydrogen peroxide products have been found to have the significant problem of a drifting baseline over time. It is difficult to maintain calibration of the sensors, and the electrode is affected by proteins and other substances in the blood stream. Although this sensing approach has had some success, its longevity in the body is much less than desired; sensors based on this approach decay after a few days of use. THERMOPILE IMPLANTABLE GLUCOSE SENSORS Towe et al. at Arizona State University have been working on an improved approach to blood glucose sensing. It depends on the fact that the glucose oxidase reaction generates a small amount of heat as indicated in the above chemical reaction. The 15 UNCLASSIFIED/ ;«F&R: 8FFI&I.«1k W&liii Ollk¥
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 45 pages are in the text index: search them above, or from the library's search.