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The essence of the original SMSI®
invention was to embed the excitation source in the
sensing element. Specifically, the invention places
a tiny, low cost LED in a matrix containing the fluorescent
indicator molecules (fluorophore) (see Figure 3).
Figure 3
For in vivo applications, a version of
the platform in Figure 4 is placed inside a bean-shaped
waveguide, encapsulated in the indicator matrix, and
combined with telemetry capabilities. A conceptual schematic
is shown in Figure 4.
Figure4
This simple concept solves numerous technical
and economic problems of existing optical sensors, as
summarized below.
- Sensitivity and Response Time
Independent - The SMSI design has eliminated the
sensitivity vs. response time trade-off inherent in
existing technology. The SMSI design delivers response
times as low as 20 milliseconds for oxygen.
- Ease of Miniaturization
- Nearly all of the components of the sensor platform
are solid state and may be reduced to an integrated
circuit.
- Dramatic Cost Improvements
- The SMSI design permits
the use of relatively inexpensive, off-the-shelf components,
and can be manufactured in high volumes.
- Energy Efficiency
- The SMSI design delivers optical energy with an
efficiency that is far superior to the current state
of the art.
- Neither Indicator nor Analyte
is Consumed - The fluorescent
indicator molecule and the analyte interact directly
yet reversibly. This is in stark contrast to commercialized
glucose sensors and electrochemical oxygen sensors,
both of which need a continuous supply of fresh glucose
and/or oxygen, as well as reagents/strips.
- Generalizable to Other Analytes
- The SMSI hardware
platform can easily accommodate different targets.
To sense a different target analyte, we simply use
a different indicator molecule in the outer layer.
Copyright © 2008 Sensors for Medicine and Science, Inc.®
All rights reserved. Date of last update: 4/8/08.
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