1. Capture Strand Verification
Target Strand Verification
Binding Verification
Problem
Microfluidic Bacterial Detection
for Resource-Limited Areas
THESIS:
Developing a paper-based microfluidic bacterial detection device
improves healthcare, especially for resource-limited communitites,
because such a device provides a reliable and affordable method of
detecting pathogens that cause illness and death.
Ethical Impact
Device Proposal
System Overview
Bacterial Contaminated Water
Willy Leineweber, Mallory Williams, Dr. Ashley Kim
Santa Clara University Bioengineering Department
Nucleic Acid Sandwich Assay
Conclusion
Acknowledgements
A
Affordable
S
Sensitive
S
Specific
U
User
Friendly
R
Rapid
&
Robust
E
Equipment
Free
D
Deliverable to
End Users
Electro-
chemical
Cell Culture
Our
Proposed
Device
1. Collect water
sample and load
onto device.
2. Unfold
device to see
result
3. Take picture to
interpret result
Inexpensiv
e device
Equal
access to
technology
Improve
awareness of
preventable
health
threats
Uphold the
dignity of
the human
person
• Bacterial pathogens in
water sourcesProblem
• Affordable pathogen
detection deviceSolution
• Improved health in
resource-limited areasImpact
3.4 million deaths yearly
Current Detection Methods
Device Use
10% of Global Health Burden
Capture DNA immobilized
on zirconia-functionalized
cellulose
Bacterial Target RNA
anneals to complementary
Capture DNA
Complementary Detection
DNA conjugated with gold
nanoparticles completes
the sandwich assay
Immobilized Capture DNA
on Functionalized Cellulose
Color Change
=
Bacteria Present
Figure 6: (1) Images taken using fluorescent microscopy of DNA tagged with fluorescent protein to verify immobilization to
substrate and annealing of Target sequence to Capture DNA. (2) Validation that images of completed sandwich assay taken
using mobile app (red) correlate with histogram data of lab microscope images (black).
Figure 2: The WHO’s ASSURED standards for diagnostic devices in
resource-limited communities and how current devices compare.[2] [3] [4]
Figure 1: WHO map showing that the areas most affected by bacteria-
contaminated water are those in under-resourced areas lacking sufficient
healthcare infrastructure. [1]
Figure 4: Schematic of device use illustrating the simplicity of design.
Device substrate is cellulose with wax printing for low-cost and
environmentally friendly manufacturing and disposal
Load
Sample
Load
Signal
Enhancer
Unfold
See
Result
Figure 3: Overview of device platform. The device uses colorimetric
detection to signal presence of bacteria. The color change can be
quantified using an app to provide concentration of the bacteria.
Figure 5: Nucleic acid sandwich assay that produces the colorimetric signal in the presence of bacteria. DNA Assays utilize the
specific nucleotide sequences unique to different types of bacteria to produce a sensitive and specific detection platform.
(1) (2)
References
We would like to thank the University Honors Program and the Miller
Center for Social Entrepreneurship for awarding us the Hayes
Fellowship and Roelandts Grant to fund our research.
[1] WHO, ed. The World Health Report 2002 : Reducing Risks, Promoting Healthy
Life. Geneva, World Health Organization, 2002.
[2] M. Urdea, et al. "Requirements for High Impact Diagnostics in the Developing
World." Nature 2006. Vol 444. pp. 73-79.
[3] Wang, J.; Xu, D.; Polsky, R., Magnetically-induced solid-state electrochemical detection
of DNA hybridization. Journal of the American Chemical Society 2002, 124 (16),
4208-4209.
[4] Storhoff, J. J.; Marla, S. S.; Bao, P.; Hagenow, S.; Mehta, H.; Lucas, A.; Garimella, V.;
Patno, T.; Buckingham, W.; Cork, W., Gold nanoparticle-based detection of
genomic DNA targets on microarrays using a novel optical detection system.
Biosensors and Bioelectronics 2004, 19 (8), 875-883.