By Matija Mraovic, Insitut za celulozo in papir (CTP). This was presented during the New Ideas for the Paper Industry: Young Researchers' Presentations session, organised as part of European Paper Week 2015. More at http://www.cepi.org/epw

1. Functional printing on paper
substrates
Matija Mraović
matija.mraovic@icp‐lj.si

2. What is?
 Intelligent packaging
 Meta‐paper / Frequency Selective Screen

3. 3
Interdisciplinary approach:
• Paper science,
• Graphical science,
• Physics,
• Chemistry,
• Biology,
• Electronics,
• Management,
• …
New designs,
New materials,
Nanomaterials?
Printed
antennas, sensors
Printed displays,
indicators
Intelligent packaging

4. Includes:
 Internal and external sensing
 Monitoring of parameters vital for the goods inside
 Parameter recording and storing for later analysis (optimization)
 Shelf life calculation
 Communication
 Protection (anti‐tampering, anti‐counterfitting, damaged…)
 Transport and storage monitoring
 Life cycle monitoring
4
Intelligent packaging

5. TRENDI RAZVOJA
Bar code >>>> RFID
5
QR code + mobile phone
 extra info
 web shopping, marketing
 …
Intelligent packaging

6. PRINTED ELECTRONICS
 Flexible materials (paper, carton, foil…)
 Functional printing inks
 Conventional printing (not same perspective)
 Passive electronic components (antennas, sensors …)
 Active electronic components (displays, ICs …)
Intelligent packaging

7. prevodna TB
Printed electronics
– functional inksConventional print (illusion)
– (CMYK) …
PRINTED ELECTRONICS
Intelligent packaging

8. PRINTED HUMIDITY SENSORS
 Capacitive humidity sensors
 Gas sensor modification (functional coating)
 RFID sensor platform
Intelligent packaging

9. 9
FABRICATED WITH SCREEN PRINTING
• Commercial conductive ink (polymer with
silver micro/nano‐particles)
• Heat curing
• Simple to fabricate
• Low resolution
• Surface roughness
• Issue with electrical contacts
TWO SENSOR TYPES
• Lateral (comb) type capacitor ‐ A
• Flat plate capacitor – B
SENSOR DIMENSIONS
• 1X1 CM (A,B)
• 2X2 CM (A,B)
• 3X3 CM (A,B)
• ARRAYS WITH ALL DIMENSIONS
OF BASE TYPE SENSORS.

10. 10
1x1 cm
2x2 cm
3x3 cm
3x3 cm array
2x2 array 1x1 array
Flat plate
1x1 cm
2x2 cm
Layout of the printing form

11. 11
MAIN GOALS:
• Design and fabricate capacitive humidity
sensors of different geometry and
configuration.
• Test sensors on different cellulose based
substrates.
• Find the optimum design (electrically and
economically) for future work.
The ultimate goal is to fabricate a RFID enabled
system with screen printed sensors for use in
smart packaging applications.
Substrates and sensor labeling
Vimax (recycled paper) C1 (1×1 cm), C2 (2×2 cm), C3 (3×3 cm); comb type
M‐Liner (cardboard) K1 (1×1 cm), K2 (2×2 cm), K3 (3×3 cm); comb type
PackPro (food packaging paper) V2 (2×2 cm); comb type
Poly‐carbonate foil PC (2×2 cm); comb type
ASSUMPTION:
SENSOR RESPONSE IS A FUNCTION OF SUBSTRATE.

12. 12
Testing in the humidity chamber at the
Faculty of electrical engineering, Ljubljana
CONSTANT TEMPERATURE: T = 23°C
RELATIVE HUMIDITY RANGE: 35 % ‐ 80 % Rh
MEASURING QUANTITIES:
• CAPACITANCE [F]
• CONDUCTANCE [S]4 MEASUREMENT SERIES:
From low (35 % Rh) to high (80 % Rh) – 5 % Rh step, step duration 1h
From high to low – 5 % Rh step, step duration 1h
Cycling the Rh from 35 % ‐ 80 % ‐ 40 % Rh – 10 % Rh step, 1h
Cycling the Rh from 80 % ‐ 35 % ‐ 70 % Rh – 10 % Rh step, 1h
• Can track up to 16 sensors simultaneously with arbitrary period ( 30s ).

13. 0
0.5
1
1.5
2
2.5
3
x 10
-10
Capacitance[F]
Time response
11:17 12:34 13:35 14:39 15:42 16:44 17:45 18:52 20:01 21:10 22:20
35
40
45
50
55
60
65
70
75
80
Time
Rh[%]
C1
C2
C3
K1
K2
K3
PC
V2
RhSet
Rh
13
Time response plot
DATA FROM CYCLING MEASUREMENT (35 % ‐ 80 % ‐ 40 % RH)
• Lazy and lower response at low Rh (< 50 % Rh)
• Saturation and over response at Rh > 80 %

14. 30 35 40 45 50 55 60 65 70 75 80
0
0.5
1
1.5
2
2.5
3
3.5
x 10
-10
Rh [%]
Capacitance[F]
Capacitance vs Rh
C1
C2
C3
K1
K2
K3
PC2
V2
14
C vs Rh plot
DATA FROM CYCLING MEASUREMENT (35 % ‐ 80 % ‐ 40 % RH)
• Logarithmic response type
• Hysteresis (evident at Rh > ~60 % Rh) higher capacitance with
moist sensor (from 80 % to 40 % Rh) lower capacitance with
dry sensor (from 35 % to 80 % Rh)

15. 40 45 50 55 60 65 70 75 80
0
10
20
30
40
50
60
Rh [%]
SR
[%]
Relative sensitivity (SR
)
C1dry
C1moist
C2dry
C2moist
C3dry
C3moist
K1dry
K1moist
K2dry
K2moist
K3dry
K3moist
PC2dry
PC2moist
V2dry
V2moist
P2dry
P2moist
15
Relative sensitivity plot: SR vs Rh
DATA FROM CYCLING MEASUREMENT (35 % ‐ 80 % ‐ 40 % RH)
• All sensors in the same region of sensitivity (also P‐C foil)
• More sensitive when moist

16. 16
In conclusion:
• SENSOR RESPONSE IS NOT A FUNCTION OF SUBSTRATE, IT'S
A FUNCTION OF CONDUCTIVE INK (POLYMER).
• LOGARITHMIC RESPONSE.
• HYSTERESIS.
• REPEATABILITY IS POOR.
• CAN BE USED FOR SIMPLE APPLICATIONS WHERE IT'S ONLY
IMPORTANT TO DISTINGUISH BETWEEN DRY AND WET.
• CHEAP (MASS PRODUCIBLE), EASILY FABRICATED AND
INTEGRATED INTO PRODUCTS (EG. PACKAGING).
PROBLEMS
• ENERGY SUPPLY
• ELECTRICAL CONTACTS

17. META‐PAPER / FREQUENCY SELECTIVE
SCREEN
• The frequency selective surfaces (FSS) are
periodic structures in either one or two
dimensions which perform a filter operation.
Depending on their construction, material and
geometry, they are divided into low‐pass, high‐
pass, band‐pass and band‐stop filters.
173D
2D - printed

18. META‐PAPER / FREQUENCY SELECTIVE
SCREEN
APPLICATIONS
• Frequency splitting
• Cassegrain reflectors
• Frequency filtering (reflecting)
• EM radiation protection
• Wireless data protection
• Antenna power directing
• IR radiation reflecting
• …
18

19. META‐PAPER / FREQUENCY SELECTIVE
SCREEN
STRUCTURE (2D – PRINTED)
• Periodic conducting patterns (meta‐cells)
• Dimensions proportional to wave‐length
• Passive antenna (reflector) analysis approach
19

20. META‐PAPER / FREQUENCY SELECTIVE
SCREEN
META‐CELL
20

21. META‐PAPER / FREQUENCY SELECTIVE
SCREEN
MEASUREMENT RESULTS
• Screen‐printing Ag‐ink
• Operation @ 3,0 GHz
21

22. META‐PAPER / FREQUENCY SELECTIVE
SCREEN
22

23. META‐PAPER / FREQUENCY SELECTIVE
SCREEN
• IR reflector (~10 micron print?)
• Printed antennas (radar, Wi‐Fi; performance?)
• Cheap solutions (maritime, cars…)
23

24. ALL ACHIEVABLE BY PRINT!
• Intelligent packaging / electronic components
• Meta‐paper (fundamental physical property of
paper altered)
24
ACKNOWLEDGEMENT:
Thanks to Vipap d.d., for supporting and fully
financing the meta‐paper research.