PRINTED ELECTRONICS:A PATHWAY TO FUNCTIONALLY-RICH
SYSTEMSVivek SubramanianEECS Department
University of California, Berkeley
Why print? Low cost?
Added functionality Integration – spatially specific deposition Customizability – digital printing Lightweight / robust / flexible
Courtesy:G. Cho, Sunchon National University
Towards a viable printing technique…
Understanding Gravure Printing
Doctor blade
Substrate
Gravure roll
Ink
Printing direction
Filling
Wiping
Transfer Spreading
Characteristics of Gravure Printing
𝜑𝜑𝑝𝑝 = 𝜑𝜑𝑓𝑓𝜑𝜑𝑤𝑤𝜑𝜑𝑡𝑡Printed volume fraction:
Capillary number
Prin
ted
volu
me
frac
tion
𝜑𝜑𝑡𝑡
𝜑𝜑𝑤𝑤𝜑𝜑𝑓𝑓
𝝋𝝋𝒑𝒑
1
0
𝜑𝜑𝑙𝑙𝜑𝜑𝑑𝑑
Gravure Scaling
1500
um
12.55um
1125
um
750u
m
7.42um
9.17um
*Gap/Width = 25%
1um 2um 5um 5um 7.5um 10um
Cell width:
187.
5um 37
5um
940u
m
6.98um
1.91um
3.35um
*Gap/Width = 5%
Nanoparticles as printable precursors Nanoparticles generally show a reduction in melting point relative
to bulk counterparts
Additionally, nanoparticles may be stabilized in solution by encapsulating them in organic ligands, which may be removed after printing by subsequent annealing
Achieved thin film conductivity as high as 70% of bulk @ <150°C!
)/1()( RTRT bulkmmelt σ−=
Huang et al, J. Electrochem. Soc, 150, 2003
Passive Components We have made numerous passive components for
use in tagging applications.
Close-up of inductor on
plastic (Q > 30 have been
demonstrated)
Close-up of capacitor, showing 2 layers of gold separated by
100nm of polyimide.
Printed Transistors
Substrate
Gate electrode is printed usinggold nanocrystals
Substrate
Low-temperature anneal forms gate stripeto edge of array (out of page)
Substrate
Polymer dielectric is depositedvia inkjet
Low-temperature anneal forms S/D stripesand connections (in plane of page)
Various active layers are deposited via inkjet
Substrate
Source / Drain contacts areprinted using gold nanocrystals
Substrate
Substrate
-30 -25 -20 -15 -10 -5 0 5 10 15 201E-11
1E-10
1E-9
1E-8
1E-7
1E-6
1E-5
1E-4
Gate current
Curre
nt (A
)
Vg(V)
Drain current
Device Characteristicsµsat
Imax/Imin (sat) µlin Vt(V) Swing (V/dec)
Average 0.58 2.77E+03 0.28 1.83 4.83
STD 0.14 4.46E+03 0.05 0.68 0.59
Number of devices: 19
-30 -20 -10 0 10 20
0.0
2.0µ
4.0µ
6.0µ
8.0µ
10.0µ
Tran
scon
duct
ance
(S)
Gate voltage (V)
0.0
0.2
0.4
0.6
0.8 S
atur
atio
n m
obilit
y (c
m2 /V
sec)
We are able to realize circuits running @ >1Mhz entirely using printing on flex
Novel devicesExploiting the advantages of printed materials
Printed healthcare analytics Thin film components needed in
biological chips can be very efficiently printed
Additive Processing- saves cost and time in fabrication
Integration of diverse biological functionality and materialson the same substrate
PCR:a) Printed Heatersb) Printed RTDs
DETECTION:OTFT Sensors
ELECTROPHORESIS:Printed Valves
Printed Heaters for PCR
Average Resistance: 33Ohms
Printed Temperature Detectors
Printed Valves for Control
Integrated PCR Chamber
16
PCR Demonstration
Printed Power Sources We’ve made printed batteries with energy density better than
thin film Li.
1000 2000 3000 4000 5000 6000 7000 80000
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Time (seconds)
Vol
tage
(Vol
ts)
Internal resistance: 24 OhmsSilver oxide utilization: 94%
The coming convergence
Novel Materials New Manufacturing Paradigms Ubiquitous systems integrating
Batteries Computation / Communication Sensing Interaction