This document summarizes a presentation about a wireless chipless passive microfluidic temperature sensor. The sensor uses two parallel plate capacitors separated by a microfluidic channel. As the temperature increases, the liquid in the channel dilates and changes the dielectric constant between the capacitors. This causes a change in capacitance that can be detected remotely. The sensor was fabricated by depositing metal plates on a glass substrate and patterning microfluidic channels. Testing showed the sensor could detect a temperature range of 9°C and had a sensitivity of 43um/°C as the liquid filled the channel.

1. 按一下以編輯母片標題樣式
NATIONAL TSING HUA UNIVERSITY
National Tsing Hua University
HsinChu, Taiwan
Presenter : Wan-Cheng Chiu (邱萬誠)
Instructor : Cheng-Hsien Liu (劉承賢)
Final Presentation
-Presentation I-
June 3, 2014
NATIONAL TSING HUA UNIVERSITY
Transducer 2013, Barcelona, Spain
Wireless Chipless Passive Microfluidic Temperature Sensor
A. Rifai1,2, E. Debourg1,2, S. Bouaziz1,2, A. Traille1,2, P. Pons1,2, H Aubert1,2, M. Tentzeris3
1CNRS, LAAS, 7 avenus du colonel Roche, F-31400 Toulouse, France
2Univ de Toulouse, LAAS, F-31400 Toulouse, France
3School of ECE, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A

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2
• Introduction
• Principle
• Concept
• Fabrication
• Characterization
• Conclusion
Outline

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3
• Introduction
• Principle
• Concept
• Fabrication
• Characterization
• Conclusion
Outline

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Introduction
Active Sensor Passive Sensor
Transmit
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Transmit
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Introduction
Bimorph Cantilever Variation of Dielectric Constant
Transmit
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Transmit
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Temperature Sensor:
Temp.
Beams bent down
Frequency
Temp.
Dielectric constant changes
Frequency
20 ℃ to 300 ℃ 19.45 to 19.30 GHz 50 ℃ to 1000 ℃ 5.12 to 4.74 GHz

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• Introduction
• Principle
• Concept
• Fabrication
• Characterization
• Conclusion
Outline

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Principle
•For two parallel plate:
+
V
-
g
Capacitance = εA/g
ε, permittivity changes for different
medium between the two plates.
Material Permittivity
Vacuum 1
Air ~1
Water ~80
SiO2 3.9

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• Introduction
• Principle
• Concept
• Fabrication
• Characterization
• Conclusion
Outline

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Concept
As temperature rises
liquid dilates
Plate capacitors
both 100nm thick
•Device Mechanism:
As the temperature rises,
the dilated liquid will
change the permittivity
between capacitors thus
causing a capacitance
change.
Glass substrate
to reduce loss
Operating frequency fixed
at 29.75GHz to match their
radar.

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Concept
Materials Permittivity
Air ~1
Water ~80
As temperature increases and
water fills up the channel, the
reflection coefficient decreases.
~The simulation proves this
method can work.~
Reflection Coefficient versus Frequency
12.5%
25%
37.5%
50%
62.5%
75%
87.5%

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Concept
The geometry of the capacitor was tuned
to allow a S11 full scale of 9dB between
full and empty channel.
400 μm
400 μm

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Concept
Without Water With Water
Capacitor
Surface
Capacitor
Surface
Vertical Axis Vertical Axis
Electric field without water is stronger and 100μm thick
water is enough to confine the electromagnetic field

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• Introduction
• Principle
• Concept
• Fabrication
• Characterization
• Conclusion
Outline

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Fabrication
Glass substrate
Glass substrate
Glass substrate
1.
2. Metalized with Ti/Cu, then patterned
3. 3050-SU8 spun on, then patterned
Glass substrate
4. Lamination of 3050-SU8

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• Introduction
• Principle
• Concept
• Fabrication
• Characterization
• Conclusion
Outline

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Characterization
Temperature range of 9℃(24 ℃ ~33 ℃) from beginning to
end of capacitor electrode.
~43μm/℃

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Characterization
∆S11~8dB for a full scale range
This corresponds to a capacitance
shift between 20fF and 140fF

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Characterization
Reflection Coefficient for Various Liquid Filling the Channel
PG: propylene glycol
EG: ethylene glycol
S11 full scale
variation are too low
for pure EG or PG
(less than 1dB).
A mixture water and
PG or EG (50%/50%)
shows an increase up
to 6dB.

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• Introduction
• Principle
• Concept
• Fabrication
• Characterization
• Conclusion
Outline

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• A new concept of passive temperature sensor
based on electromagnetic coupling between an
RF capacitor and dielectric liquid has been
presented.
• This type of temperature sensor obtained a
high sensitivity.
• Water has been replaced to avoid evaporation
problem.
Conclusion

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~Thanks for your attention~