2. Project Goal
To build affordable portable rapid diagnostic
devices that can successfully aid in disease
control
Our project focused on the mechanical side of the device.
The molecular technology used for disease detection will
be covered, but was not a main component of our research.
3. Device Function
A liquid drop of the sample is placed on a slide,
and the drop is physically aligned between the
emitting LED and the detecting photodiode and
fiber optic receiver.
4. Device purpose and benefit
● Rapidly diagnose blood and tissue samples
in the field
● Inexpensive user-friendly device for reliable
disease control device
● Alert government of problematic disease
areas quickly and before outbreaks
6. Key Device Features
● Battery powered - easily available 9V power
source in any country
● Low power signal - Light Emitting Diode (LED)
emission signal with a fiber optic cable and
photodiode to receive the signal after passing
through the sample
● Indicator LED - indicator light turns off once
sample is properly aligned
● Circuit - Operational amplifiers detect amount
of light scattering (positive or negative sample)
7. Historical Background
Rapid Diagnostic Tests (RDTs) are the
prefered method of testing samples in the field
where microscopy or a laboratory may not be
practical
RDTs provide a user with a quick reliable way
to classify positive and negative samples
Major drawbacks of many RDTs is their high
cost
9. Molecular Detection
Disease detecting antibodies are conjugated
with gold nanoparticles
In positive samples,
antibodies will cluster
around infectious areas.
In negative samples, the antibodies have no
preference for a particular site, and the
distribution will be uniform.
10. Distinguishing Samples
Positive and Negative samples are
distinguished by light scattering from gold
nanoparticles
A uniform negative sample will focus light
through the drop as expected
A positive sample will have areas of clustered
gold nanoparticles, and create a lower signal
reading
12. Sample Alignment
For consistent readings, light must hit the drop
a the same angle every time.
To accomplish this, an optical property of
curved surfaces is incorporated to ensure
proper alignment
Optical caustics aid in the visual alignment
13. Optical Caustics
A caustic is the bright pattern of reflected or
refracted light rays on one surface to another
The recognizable shape has been used in
many other fields, especially digital image
rendering
14. Application of Caustics
A curved surface, in this case a liquid drop,
creates a bright area where the signal is most
intense
Using operational amplifiers, the reading from
the fiber optic reciever is processed and the
indicator LED is shut off when the brightest
region of the caustic is properly aligned
15. Consequences of Device
Consistent readings can be taken using a
simple monochromatic LED.
Affordable technology can be used with little
training
Rapid results can be generated and regional
conclusions can be gathered within a day
16. Further Work to Do
Magnetic stabilizer - sample alignment is
critical to the device, there are plans to
implement a magnetic coupling to ensure
emitter and receptor pieces remain stationary
Rechargeable Power Source - the current 9V
source can take rechargeable 9V batteries. We
are also looking into adding a photovoltaic cell
to aid in the recharging batteries
17. Application and Impact
Affordable health care is in constant need in
order to accelerate growth of developing
countries
This device proves especially helpful in south
american countries combating the spread of
mosquito transferred diseases
Early detection can save a government millions
of dollars, as opposed to treating a wide spread
18. Acknowledgements
Sokolov K, Follen M, Aaron J, Pavlova (2003)
Real-time vital optical imaging of precancer
using anti-epidermal growth factor receptor
antibodies conjugated to gold nanoparticles.
Johannes Kofler (2004)
Focusing of Light in Axially Symmetric Systems
within the Wave Optics Approximation
