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