Analytical Devices Made Out of Patterned Paper
Andres W. Martinez
Department of Chemistry & BiochemistryCalifornia Polytechnic State University
Microfluidic Paper‐Based Analytical Devices (MicroPADs)
• Millions of people die every year from preventable disease.
• Effective diagnosis of disease is the first step towards an appropriate treatment.
• 1st world diagnostic technologies are not always useful in developing countries.
A Global Problem
ASSURED Diagnostic Tests
AffordableSensitiveSpecificUser‐friendlyRapid and robustEquipment‐freeDeliverable to end‐users
—World Health Organization
Current Diagnostic Technologies microfluidic devices dipstick assayslateral‐flow assays
(pregnancy test)
MicroPADs
large‐scalemanufacturing
easy to stackand transport
disposable
versatilefunctionality
aldehydes, acids, amines, cations, anions, etc.
1)
3)
4)
Paperlow cost ($0.15/m2
for paper towel),widely available in many types
2)
wicks fluids
5)
6)
Why isn’t everybody making paper-based diagnostic devices?
1 cmurinalysis dipstick lateral-flow immunoassay
(pregnancy test)
Channels in Paper
1 cm
Fabrication by Photolithography
i. apply photoresist
ii. pre‐bakeiii. align under a mask
iv. expose to UV lightv. post‐bake
vi. develop
paper
mask1 cm SU‐8 photoresist
chromatographypaper
oblique view cross‐section
Martinez, A.W. et al. Angew. Chem. Int. Ed. 2007, 46, 1318‐1320
Fabrication by Wax Printing
1 cm
wax hydrophobic barriercross‐section:
Carrilho, E. et al. Anal. Chem. 2009, 81, 7091‐7095
Assays on microPADs: Detection of Glucose and BSA
BSA assayreagents
1 cm
exposed to an artificial urine solution containing
glucose and BSA
glucose assay
reagents
[BSA](μM)
500
50
10
5.0
2.5
0
[glucose] (mM)
75
7.5
1.5
0.75
0.38
0
0.5 cm
Quantitative Paper‐Based Assays
1 cm
Mean: 130.12
Dip device into sample
Device wicks sample into test zones
Color develops for each assay
Scan or photograph the device
Select test zonesand record mean intensity using Adobe®Photoshop®
Martinez, A.W. et al. Anal. Chem. 2008, 80, 3699‐3707
[Glucose], mM
Known Concentration
Observed Concentration
2.5 2.3 ± 0.5
3.5 3.9 ± 0.7
4.5 4.5 ± 0.7
[BSA], μM
Known Concentration
Observed Concentration
25 27 ± 7
35 36 ± 8
45 44 ± 7
Telemedicine: Quantitative Assays Using a microPAD and a Camera Phone
Three‐Dimensional microPADs
Martinez, A.W. et al. Proc. Natl. Acad. Sci. U.S.A. 2008, 105, 19606‐19611
0.2 min 2 min 4 min
• 4 samples distributed into 64 detection zones.3‐D μPADs for Sample Distribution
Paper‐Based ELISA
Cheng, C.M. et al. Angew. Chem. Int. Ed. 2010, 49, 4771‐4774
Paper‐Based ELISA vs. Bench‐Top ELISA
ConclusionsMicroPADs are a new platform for ASSURED
diagnostic tests.
MicroPADs: 1. are simple to use2. detect multiple analytes3. are portable4. are inexpensive5. use small volumes of sample
AcknowledgmentsGeorge WhitesidesManish ButteEmanuel CarrilhoChao‐Min ChengAudrey EllerbeeMalancha GuptaNina JainJustin KohMonica Mascareñas
Katherine MiricaZhihong NieScott PhillipsAdam SiegelHayat SindiSam ThomasSarah VellaBen WileyThe Whitesides group
Questions?
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