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Microfluidics and Biosensors for Point-of-Care Diagnostics
Xuanhong Cheng
Materials Science and Engineering
Bioengineering Lehigh University
November 24, 2014
Basic Water Supply Microfluidics for Medicine
Micronit.com
Advantage of Microfluidic Systems
• Small sample volume • Small reagent volume • Low production cost • Portable, potential for integration and
automation • High surface to volume ratio • Laminar flow, predictable transport
property
POC Diagnostics
Master
Micro-scale Fabrication
CD4 Count
Time (years)
6 4 2
1000
200
WHO Stage 4 AIDS CD4 < 200 TB, infections Death ~18 months
WHO Stage 2 and 3: Symptomatic HIV infection CD4 200 - 500 Mild infections Weight loss, fatigue TB, Thrush
WHO Stage 1: Asymptomatic HIV infection CD4 >500
350
HIV Diagnostics
CD4
Viral load (HIV RNA level)
time Years Weeks
Begin ART
Impact of Treatment
Basic Water Supply Clinical Indicators
Years
Weeks
‘Viral load’
HIV RNA level
(copies/
mL plasma)
1 2 3 4 5 6 7 8
CD4 cell count
(cells/µL blood)
900
800
700
600
500
400
300
200
100
0
108
107
106
105
104
103
102
101
100
Basic Water Supply State of the Art Technologies
BD FACSCalibur
RT PCR
CD4-count start treatment < 200 cells/ul
Viral load count measure resistance to treatment
Basic Water Supply Lab Diagnostics in Resource Poor Settings
• Low cost
• Easy to use
• Rapid and Robust
• Portable
• Sensitive and specific
What is Needed
Basic Water Supply Microchip Technology for Medicine
Portable CD4 Counter
K+ Cl-
Na+K+ K+
Cl-
Cl-
Cl-
Cheng, X. et. al, Lab on a Chip, 2007
Microfluidic Cell Counting Chip
Daktari Diagnostics Inc.
CD4 counting microchip
• Controllable pore size • High porosity • Bio-functionality • Tight pore size distribution • Thin membranes
Nanoporous Membrane for Viral Processing and Sensing
PDMS membrane
Embedded Nanoporous Membranes for Virus Capture
Embedded Nanoporous Membranes for Virus Staining
Optically Forced Cytometry for Nanoparticle Counting
• Significant in clinical diagnosis, biohazard surveillance, food safety monitoring, etc.
• Contemporary approaches require laboratory access • Electrical test can be fast, compact, sensitive and label free
Flow Cytometer Cell Staining Molecular Markers
Detection of Bacteria Viability
HP Schwan (1985): Hypothesis based on :ssue measurement
Frequency (Hz)
Dielectric Con
stan
t
Cond
uc:v
ity (m
S/cm
)
Cellular Proper:es
Subcellular Proper:es
Molecular Proper:es
Broadband Electrical Sensing
22
Broad Band Electrical Sensing
Syringe Pump Inverted
Microscope
Signal Generator
Network Analyzer
High-‐Speed Oscilloscope
Micro-‐ Chamber
Cells In
RF In
Experimental Setup
Cells In
RF In
RF Connector
Cells in μ-‐Chamber
RF Connector
Transmission
Input
Reflec2on
Sample Volume = 20 cubes of 10μm×10 μm×10 μm
Modeling to Extract Cell Information
Cell Immobilized by Dielectrophoresis
0
0.5
1
1.5
2
0 5 10 15 20
S 11 D
isp. (1
0−10 dB/Hz
)
No. of Cells Trapped
S11 Live
S11 Dead
Differentiating Live vs Dead HEK Cells
0
0.25
0.5
0.75
1
0 5 10 15 20
S 11 D
isp. (1
0−10 dB/Hz
)
No. of Cells Trapped
S11 Dead Jurkat
S11 Dead HEK
HEK Jurkat
Differentiating Dead HEK and Jurkat Cells
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0 0 500 1000 1500 2000
aver
age
delta
S11
(dB
) Number of bacteria
Live
Dead
Differentiating Live and Dead E. coli
0 0.2 0.4 0.6 0.8 1
1.2 1.4 1.6
0.01 1 100 Ab
sorban
ce
Log scale Conduc:vity (mS)
CM1 19 h
LB 19h
Culture
Biofilm Monitoring on a Chip
Next Steps • Monitor biofilm growth on
chip • Screen anti-biofilm reagents
Acknowledgments
Collaborators Fil Bartoli Arthur Chiou (Yangming U, Taiwan) Tim Friel (LVHN) MarJn Hirsch (MGH) Jim Hwang Jim Gilchrist Sabrina Jedlicka Yaling Liu Alp Oztakin Daniel Ouyang William Rodriguez (MGH) Olga LaJnovic (IHV) Peikuen Wei (Academia Sinica, Taiwan) Frank Zhang
Students Caroline Multari Krissada Surawathanawises Bu Wang Chao Zhao
• Controllable pore size • High porosity • Bio-functionality • Tight pore size distribution • Thin membranes
Nanoporous Membrane for Viral Processing and Sensing
Embedded Nanoporous Membranes for Viral Processing
Perc
enta
ge o
f Viri
ons
(%)
0
20
40
60
80
100
120
200nm Pores 20nm Pores
Filtrate
Absorbed on membrane
Suspended above membrane
Vira
l Con
cent
ratio
n (/m
L)
0
2e+7
4e+7
6e+7
8e+7
Original Sample 1mL filtration + 10µL Wash
% o
f Viri
ons
Cap
ture
d on
Mem
bran
es
0
10
20
30
40
50
60
70
Bare PEG
AntiCD44
Community-based Care
Care takes place in the community. Reinforced in the
clinic.
