Screen-printed potentiometric sensors for...Screen-printed potentiometric sensors for quantification...
Transcript of Screen-printed potentiometric sensors for...Screen-printed potentiometric sensors for quantification...
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Screen-printed potentiometric sensors for quantification of multiple ions
M.A.G. Zevenbergen, V.A.T Dam, M. Goedbloed, G. Brom-Verheyden and R. van Schaijk
Imec/Holst Centre, 5656 AE Eindhoven, The Netherlands
Email: [email protected]
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© Holst Centre
Multiple ionic concentrations using a single sensor
• Continuous long-term monitoring
• Mass producible by microfabrication
• Disposable, point of care • Conformable, flexible • Mass producible by printing
and dispensing
Solid state Screen printed
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Ion sensor; applicable in many areas
Specific set of ions tailored to the application is key!
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Sensor transducing mechanism
K+
K+
membrane
K+
K+
K+
K+
K+
Cl-
Cl-
Cl-
test fluid Ion selective membrane contains:
• polymer matrix
e.g. polyvinylchloride
(PVC)
• Ionophore
forms selective complex
with the ion to be
determined
• Lipophilic ionic sites R-
maintain charge balance
R-
R-
R-
R-
Inner electrolyte
K+
Cl-
K+
Cl-
0.1 M KCl
AgCl ele
ctr
ode
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Sensor fabrication: AgCl electrodes
A4 polyethylene terephthalate (PET) sheet
Sensing electrodes: multiple printed AgCl layers
• DEK HORIZON O3i printer
• Dupont 5876 Ag/AgCl paste
• DuPont 8153 insulating paste
6
Sensingelectrodes
Referenceelectrode
After optimization of printing: thickness, viscosity, composition etc. electrode drift
< 1 µV/hr for more than a week
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Sensor fabrication: lamination in TPU foil
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Reference electrode
Reference potential independent on composition test fluid
• AgCl electrode modified with hydrogel
• PVC polymer matrix containing KCl
0 4 8 12 16-25
-20
-15
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Vo
lta
ge
(m
V)
Time (hrs)
Drift increases
(leakage KCl)
Reference electrode can be used for ~15 hrs then recalibration is required Note: shelf life sensor > 2 months
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Sodium and potassium ion selective membranes
• Similar hydrogel as reference electrode is drop casted as internal electrolyte
• Covered by Na+ and K+ selective
membranes
substrate
isolation
TPU
AgCl electrode AgCl electrode
hydrogel
AgCl electrode
Cross-section:
hydrogel
K+ selective membrane
hydrogel
Na+ selective membrane Reference electrode
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Hand held wireless ion sensor
• Sensitivity for ion > 55 mV/decade • Range: 10-4 M – 1 M, 10% accuracy • No cross sensitivity • Work in progress: nitrate ion
Demonstrator at Holst Centre booth!
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Roadmap
Solid state pH/chloride sensor
Flexible platform added
Extension to other ions, Na+
and K+
Increase life-time, mass-producible with dispense tool
Algorithm development, E-tonque
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Conclusion
• Holst Centre’s ion sensor is a versatile fluid sensor platform
• Multiple miniaturized sensors in 1!
• Tailored to a specific application
• Demonstrators are available
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Acknowledgement
Ion-selective membranes
Dr. Louis de Smet, Prof. dr. Ernst Südholter
Chuan Nie, Dr. Arjan Frijns, Prof. dr. ir. Jaap den Toonder
Sweat patch