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“Flexible and Printed Electronics for
Sensors, Displays and Photovoltaics”
Jurgen Daniel, T. Ng, A.C. Arias, L. Lavery,
S. Garner, R. Lujan, W. Wong, R. Street, B. Russo, B. Krusor
Palo Alto Research CenterPalo Alto, California
International Workshop on Flexible and Printed Electronics (IWFPE 10), Sept8-10, 2010, Muju Resort, Korea
DARPA
about PARC (www.parc.com)
Research with client companies
Government contracts
Partnerships with new ventures
(startup @PARC)
New business creation
Licensing and
technology transfer
Research as a business:
• formerly Xerox PARC
• Incorporated in 2002
• ~170 researchers
Palo Alto Research Center
Computer Sciences
Intelligent Systems
Hardware and Systems
Electronic Materials & Devices
4 Labs:
• MEMS, Optoelectronics, Printing concepts/Systems, PiezoMaterials, Biomedical Systems, Clean Technology, ...
Large area + Printed Electronics
Nokia concepts
The Vision of Flexible/Printed Electronics
Antenna Design conceptElectronic Patch Network (DK)
Displays, sensors, RFID, batteries, solar cells, lighting, …
Freshness sensor
(RF, H2S gas)
ITRI/ UCSB
Flexio : Yanko design
e-Drum
PARC Competences in Flexible Electronics Low-T a-Si and poly-Si, GIZO, nanowires
Organic electronics
Printed Electronics
Materials and substrate evaluation
Device physics and design
Device, array and systems prototyping
Circuit design and prototyping
Charge transport
Display system
X-ray imaging system
Printing system Printed pixel circuit Thin-film transistor
A portfolio of technologies
Flexible displays for electronic paper applications
6” digital lithography a-Si:H array
bistable image after ~1 month
8” low-T a-Si:H photolithography array
Display medium: E-ink electrophoretic imaging film
“for electronic paper applications”
Flexible Electrophoretic Displays (with low-T a-Si:H)
340 m pixels (74ppi)
• on/off ratio: ~107
• ~0.9 cm2/Vs
TFT: T < ~170 degC
(Inkjet based digital lithography)
W.S. Wong, et al., “Digital lithography for large-area electronics on flexible substrates”, J. Non-Crystalline Solids 352 (2006) 1981
W.S. Wong, et al., “Digital lithographic processing for large-area electronics”, J. of the SID, 15/7 (2007) 463
J. Daniel, et al., “Jet-printed Active-Matrix Backplanes and Electrophoretic Displays”, JJAP, Vol.46, 3B (2007) 1363-1369
Flexible Displays with Printed Backplane
50x50 pixels(~2 inch diag.)
37ppi
PEN substrate
PVP gate dielectric
Printed Ag
PQT semiconductor680 m pixels; PQT-12 jet-printed
Semiconductor
Display medium: E-ink electrophoretic imaging film
„active-Matrix pixel circuits for electrophoretic media‟
All-additive solution processA.C. Arias, et al., J. of the SID, 15/7 (2007) 485
J. Daniel, et al., SID 09, 44.3, 660
J. Daniel, et al., Proc. NIP25 and Digital Fabrication 2009, 599
movie
Printed TFT Backplane : layers
50x50 pixel arrayGate layer
Data layer
Pixel design
Printed pixels (PQT TFT)
Larger feature sizes -> good, e.g. for poster size displays
50x50 pixels37ppi
680 m pixels
PQT-12 jet-printed OSC
Jet-printed nano-silver
192 m
Printed Display Challenges Resolution and speed are important considerations
Consider printed displays for poster-type or small disposable displays
Data line
(4.5 micron)
Pixel pad
Photolithography Jet-printing
37 ppi
74 ppi
(~50 micron)
Commercial backplane
Multi-Layer pixel design requires via interconnect formation
200 m pixels should be possible without
further reducing a 50 m line width
Multi-layer Pixel Design
side view
top view
Display Resolution: Multi-Layer Pixels
„Printed Metal Mask‟ (PMM) Via Process
“Process uses same printer for
mask deposition as for
metal conductors”
Via processes are required also for many other electronic circuits
photopolymer
GND
20.619.3
12.414.2
8.3 8.7
7.2
Process:
- Deposit photopolymer
- Print silver mask -UV expose
- Remove unexposed polymer
- Print top-layer with silver
Via chain
Circuits with Printed Metal Mask Via ProcessShift-register and Pixel circuit
1G-2D pixel circuitDynamic shift-register
Complex circuits can be patterned using silver jet-printing only
Pixel TFT:
- PBTTT
(spin-coated)
PBTTT
-also well formation to confine OSC
PARC Printed Blast SensorTape
Pressure, acoustic, acceleration, light sensor integration
Readout electronics and memory (data storage for 7 days)
Printing/lamination processes for low cost (target ~<$1)
Peak-detect and 5ms recording of events
challenges
“to record blast events
that can cause
Traumatic Brain Injury (TBI)”
• pressure wave
• sound
• acceleration
• (light)
• (temperature)
explosion
source: MicroVision
disposable blast dosimeter tape
DARPA Sensor Tape Program
Approved for Public Release, Distribution Unlimited
Sensor tape development faces many new challenges
www.brainline.org
Existing Football Helmet Sensor
Lower cost solutions are desirable
The HITS helmet (for Head Impact Telemetry System)
monitors the precise location and severity of impacts.
Acceleration sensing:
-uses 6 accelerometers
Stick-on Sensor Tape Examples
Paksense: Temp data logger
Parlex: Oximetry sensor patch
Huggies: UV sensor patch
Axcess: Asset & patient tag
IMEC(NL): Flexible ECG patch
Electronic PatchNetwork (DK)
Ocean Optics:Oxygen sensor patch
NASA: sensor medical patch
Flexible, disposable sensors
“Printing” may include many Processes
Inkjet, gravure, offset, flexo, (rotary) screen, …
Microcontact, Nanoimprinting
(Laser) transfer printing (of high performance circuits)
Dip-pen nanolithography
Hot embossing
Vapor-phase printing
Laser processing (cutting sintering, patterning)
Stamping/die cutting
Slot-, dip-, spray-coating
Etching, R2R photolithography (!)
Lamination, …
The consumer does not care if and how a product is ‟printed‟
Requirements are more demanding !
Sensor Tape in Comparison to EP Displays
Low-voltage operation (low power)
CMOS (p- and n-type TFTs)
Higher speed
Continuous operation (some circuits)
Readout Precision
…
(Electrophoretic)
sensors
clock circuit
amplifiers
memory
thin-film battery
printed
+ conventional external
readout electronics
Sensor tape
Sensors
Light sensor
•100-400klux
•„all-printed‟
Accelerometer Pressure / Sound
- mechanical sensors based on
piezoelectric polymer (PVDF):• low power
• low drift
• compatible with R2R process
Sensor fabrication compatible with R2R fabrication
• 0-1000g (+/-10%)• 5-100psi (+/- 10%)
• 100-180dB (+/-10%)
Light Sensor All –inkjet printed
In comparison: PCBM (EQE>50%)
had stability issues when processed in air
All-printed light sensor with photo response up to 400,000 lux
air-stable blend
Leah, Lavery, submitted to ‘Organic Electronics’
Piezoelectric sensing is well suited for blast events
Mechanical Sensor Options
• Substrate flexure
• Stress
• Low power consumption
• Fabrication process (printing/ R2R)
Considerations:
methods Properties/issues
Capacitive drift issues, readout relative complex
Piezoresistive drift, high power consumption
optical complex; high power consumption
Magnetic high power consumption; complex
Piezoelectric low power; good for transients
Compatible with solution/web
processing
: stress
t: thickness
g: piezo-coefficient
Piezoelectric sensing
Sensor Components Piezoelectric sensing (laminated PVDF foil or PVDF-TrFE solution)
punched
polycarbonate
rigid
substrate
Flexible PCB sensor
foil
sensor with charge
amplifier
printed silver electrodes on
PVDF/steel foil
Components of sensors with conventional electronic amplifier readout
pressure
acceleration
Approved for Public Release, Distribution Unlimited
Similar processes for pressure, acoustic and acceleration sensors
Measurement Setup – example: pressure
PARC blast tube (for faster pulses)
To simulate blast event and to enable repetitive measurements
Pressure Pulse Generator
Enfieldvalve
PARC sensor
Endevco reference sensor
Pressure
chamber
~ 4 psi blast
Commercial sensor
PARC sensor
P
sensor
Pressure / Acoustic Sensors
~ 4 psi blast
Commercial sensor
PARC sensor
PARC sensor
commercial sensor
• 10 pressure sensors: 5-100psi
• 10 acoustic sensors: 100-175dB
sound
pressure
Piezoelectric polymers by lamination or solution process
Piezoelectric sensing (PVDF / PVDF-TrFE)
Sensor Calibration and Verification
@ 500Hzacoustic
pressure~1% error
Light sensorAccelerometer
Pressure Sound
Sensors were within +/-10% allowed error
Verification was performed with DARPA observer present
Sensor Endurance Test
PARC Sensor
Endevco
Pressure sensor withstands multiple pressure pulses
The Electronic Components
Ring oscillator Shift Register
-120
-80
-40
0
-60 -30 0 30 60
gate voltage [V]
so
urc
e-d
rain
cu
rre
nt
[nA
]
Vsd= -10 V
(a)
0
25
50
0 -20 -40 -60
switching voltage [V]
dif
fere
nce
in
cu
rre
nt
at
Vg=
0V
[n
A]
(b)-120
-80
-40
0
-60 -30 0 30 60
gate voltage [V]
so
urc
e-d
rain
cu
rre
nt
[nA
]
Vsd= -10 V
(a)-120
-80
-40
0
-60 -30 0 30 60
gate voltage [V]
so
urc
e-d
rain
cu
rre
nt
[nA
]
-120
-80
-40
0
-60 -30 0 30 60
gate voltage [V]
so
urc
e-d
rain
cu
rre
nt
[nA
]
Vsd= -10 V
(a)
0
25
50
0 -20 -40 -60
switching voltage [V]
dif
fere
nce
in
cu
rre
nt
at
Vg=
0V
[n
A]
(b)
0
25
50
0 -20 -40 -60
switching voltage [V]
dif
fere
nce
in
cu
rre
nt
at
Vg=
0V
[n
A]
(b)
Memory
Inverter
T. Ng, APL 94 (2009) 233307
- Complementary Electronics
- Ferroelectric (PVDF) memory
- Peak detect circuit for speed
CMOS electronics for low power and better performance
Low Voltage TFTs ALD dielectric (100nm HfO2 on printed Ag gate electrode)
Ci~ 60-65 nF/cm2
Low voltage TFTs are required for low power and battery operation
2V
10V
3V
10V
N-type P-type PBTTT
collaboration:
(additional thin
low-k polymer on HfO)
• printed Ag source/darin
Printed Complimentary Inverters
DC characteristics AC characteristics
Inkjet-printed complementary inverter
• Gain of -4 at supply voltage of 20V
• printed TFTs show p type mobility ~0.1cm2/Vs,
n type ~0.05cm2/Vs
Inverters as building block for logic and amplifier circuits
T. Ng, APL 94 (2009) 233307
Pressure Sensor with Printed Inverter
Endevco
Inverter as high-impedance sensor-signal input
Confirmed inverter operation
printed inverter
pressure sensor
Printed Uni-polar inverter coupled to
PVDF-TrFE pressure sensor
J. Daniel, et al. (to be published in Proc. IEEE Sensors 2010)
Stick-on Sensor Tape Concepts
Approved for Public Release, Distribution Unlimited
Printing enables large-area multifunctional sensors with redundancy
Printing enables multifunctional designs with redundancy
- conformal
- large area
- with redundancy
Sensor designs:
Large-area flexible Photosensors
p-i-n aSi
Array sensitivity limit on flexible substrates:
• organic blend = 30 pW/cm2
• amorphous silicon = 1.2 pW/cm2
T.N. Ng, et al : Appl. Phys. Lett. 92(2008) 213303; Appl. Phys. Lett. 91(2007) 063505
organic heterojunction blend (MEHPPV: PCBM 1:3)
p-i-n amorphous silicon
Starlight ~50 lx ~7 pW/cm2
Clear night sky ~1 mlx ~150 pW/cm2
Flexible photosensors processed at low temperature (<160 degC)
Flexible PV Concept by Mosaic TilingConcept:
• use high efficiency conventional cells
• flexible or textile substrates
• combine with other electronic tiles
mixing of tiles
Novel tiling concept enables multi-axis flexibility
contacting concept
SunPower cell
Summary
PARC has a portfolio of technologies and services for flexible and printed electronics
PARC is evaluating materials and developing processes for printed electronics
Inkjet-printing is particularly advantageous in prototyping phase and for applications where non-contact printing is desirable
Flexible and printed sensor technology will enable novel applications
Acknowledgment
PARC: S. Sambandan, C. Paulson, S.E. Ready
DARPA (contr. # W81XWH-08-C-0065)
Cambridge Nano Tech Inc. : Jill Becker, Ritwik
Bhatia, Ganesh Sundaram
Naval Medical Center San Diego: Ron Jackson,
Jianzhong Liu, John Coleman
Polyera
Xerox Research Center of Canada
Measurement Specialties (MSI): Mitch Thomson
DuPont Teijin
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