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AAWSAP DIRD, Biosensors and BioMEMS: A Survey of the Present Field, March 2010

U.S. Department of War · 2010-03-31 · 45 pages · text from the file's own layer

This Defense Intelligence Reference Document, dated 31 March 2010 and numbered DIA-08-1003-020, was prepared by the Defense Intelligence Agency's Defense Warning Office under its Advanced Aerospace Weapon System Applications Program. It surveys biosensors and biomedical microelectromechanical systems, covering brain-implanted micromachine neuroelectrodes, drug-delivery pumps, glucose sensors, neural interfaces, retinal prostheses, microfluidic lab chips, NASA cell-culture systems and microcantilever sensors. It concludes that the field is expanding rapidly, with nanomechanical systems expected to follow.

From the source:Release of 2026-09-18 Incident: 3/31/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys biosensors and BioMEMS, a broad class of miniature biomedical devices that combine microscale engineering with sensing, fluid handling, stimulation, or drug-delivery functions. The report reviews major application areas including implantable blood-chemistry sensors, neural interfaces, neurostimulation, drug-delivery pumps, microfluidic systems, and emerging nanoscale extensions of the field, while emphasizing that miniaturization can improve sensitivity and enable functions that are difficult or impossible at larger scales. However, it also makes clear that practical development is constrained by biocompatibility, long-term stability, sensor drift, device degradation inside the body, and the high regulatory burden associated with implantable medical systems. The document presents BioMEMS as a rapidly growing and productive field whose future advances are likely to come through continued improvements in fabrication, materials, and reliability.

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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.
Adva nced BioSensors blood glucose sensor
- Flip chip assembly
AS ICs , pow er sources and circui componen s
Separa e sensors, moun w i h electrical
connec ions, add he biocompa ible polymer,
assemble he sensor pa ch.
The sensor based on glucose oxidase reacti on
wi h blood plasma from ca pill aries in he dermi s.
- biochemical coa ing - sensor in place 3 - 7 days
- Docking par for elec ronics assembly w i h
amplifi er, ADC , w ireless transceiver , pow er source
- encryp ed digi al da a to w ri stwa ch-sized
morn or/ record er module
In fu ure combine the CG S wi h an insulin pump long x 200 u Ide
o produce a closed-loop sys em-an artifici al
pancreas.
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Figure 11. An Experimental MEMS Blood Glucose Sensor
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 alter 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
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Official release, from the pursue 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.