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: marcel.zevenbergen@imec-nl.nl

© 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

© Holst Centre

Ion sensor; applicable in many areas

Specific set of ions tailored to the application is key!

© Holst Centre

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

© Holst Centre

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

© Holst Centre

Sensor fabrication: lamination in TPU foil

© Holst Centre

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

-10

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

© Holst Centre

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

© Holst Centre

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!

© Holst Centre

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

© Holst Centre

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

© Holst Centre

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