Printing Flexible Electronics for Health Care Applications

Printing Flexible Electronics for health care Applications

Pit Teunissen

Eric Rubingh

Ruben Lelieveld

Marc Koetse

Juliane Gabel

Pim Groen

Printed and organic electronics

November 20, 2014

Presentation overview

Printing Flexible Electronics for health care Applications, Pit Teunissen

1. Introduction smart blister

2. Device architecture

3. Way of working

4. Results

5. Towards high volume production

6. Conclusions

7. Outlook

© Holst Centre

Smart Blister

• Pharmaceutical package capable of monitoring when a pill is taken out of its packaging

• Data can easily be transferred wireless via NFC

• Main purpose: To ensure that patients in clinical trials take their medicine at the time and frequency recommended to avoid non-compliance issues


© Holst Centre

Smart blister: Partner request


• Assembled

• “3D”-system

• High cost

• Added to existing package

• Fully integrated

• 2D-System in Foil

• Low cost, mass fabrication

• Roll to Roll compatible

Request from partner: from assembled PCB to low-cost integrated system in foil

© Holst Centre

Technological challenges

System engineering

• Simplification, cost reduction

• Optimal chip set

• Design rules

Printing

• Conductivity (Antenna)

• Multi layer (circuitry)

• Overlay precision

Assembly

• Adhesives

• Accuracy

• Reliability and durability




1. Introduction Smart blister


3. Way of Working

4. results


6. Conclusions

7. Outlook

© Holst Centre

Substrate selection

Substrate:

• Price

PI >50€/m2

PEN <10 €/m2

PET <1 €/m2


Preferred substrate PET

• Tg PET ~ 100°C

Processing temperature < 130 °C

© Holst Centre

Building Blocks


sensing

logic

radio

antenna

power Thin film battery

Resistance ladder to monitor which pill was taken from package

Integrated chips for measuring and registration

Printed antenna for data transfer

Integrated chips for RFID communication and data storage

© Holst Centre

Deposition method

Processing:

• High speed processing / large volume

R2R compatible

High speed

Resolution ~100µm features

Multi-layer 100µm overlay accuracy

High aspect ratio for high conductivity


Screen printing

© Holst Centre


Device layers

• Five layers

1: Circuit including antenna

~100µm feature size

Good conductivity

2: Antenna

~100µm overlay accuracy

~100µm feature size

Resistance ≤40 Ω

3: Dielectric

Good insulating properties

Prevent shorts in crossing layers

4: Bridges

Make electrical contact between components

5: Printed resistors

Monitor which pill is taken out

Accurate resistance (< 5% deviation)

© Holst Centre


Components

Components

• 3 chip solution

MC: micro controller (measure and register)

RTC: real time clock (date, time)

NFC Eeprom: RFID communication and data storage

• Thin components

Components can be integrated in foil

• Assembly

No soldering possible!

Use novel low T cure isotropic conductive adhesives (100 °C cure)

without package

thinning chip down to 20-30 µm

chip becomes flexible





3. Way of working

4. Results


6. Conclusions

7. Outlook

© Holst Centre

Way of Working – Deposition method

• Screen printing: principle

Paste is applied in a patterned mesh

Mesh is positioned above substrate

Ink is pushed through the mesh and a direct image of the screen is made on the substrate


smallest feature size (lab)

30 m

smallest feature size (industrial scale)

80 m

ink viscosity range 100 – 800,000 mPas

wet layer thickness 12 – 500 m

dry layer thickness 0.5 – 50 µm

dry layer thickness accuracy

15 – 40 %

alignment/overlay accuracy

100 m

Processing time < 1 min. / sheet

Woven mesh

© Holst Centre


Way of working – Equipment and materials

• S2S screen printer

DEK Horizon 03i

• Mesh technology

Stainless steel woven mesh

Stork Prints PlanoMesh, electroformed Nickel

• Materials

Silver paste (layer 1, 2 and 4)

1: Circuit, including antenna (DuPont 5025)

2: Antenna (DuPont PV410)

4: Bridges (DuPont 5025)

Isolator (layer 3)

3: Dielectric (DuPont 7165)

Carbon (layer 5)

5: Resistors (DuPont 7082 + DuPont 5036)

Stork Prints PlanoMesh

Dek screen printer

© Holst Centre


Way of working – Sintering

• Sintering

Metal nano,- and micro particle need to be dried and/or sintered to become conductive

Sintering = merging particles via atomic diffusion

Fraction of the bulk melting temperature

Nanoparticle inks are ideal for conductive structures on temperature-sensitive substrates

Sintering can be done thermally, photonically, electrically, using plasma, chemically, etc.

Here we use thermal sintering in an oven at 130°C

Sintered Ag nanoparticles





3. Way of working

4. Results


6. Conclusions

7. Outlook

© Holst Centre

Results


• 1st layer: circuit for electrical contacts

Smallest line width: 100µm

Good Conductivity

Typical line height ~6µm

Profile measurement antenna Screen printed circuit

© Holst Centre

Results


• 2nd layer: antenna

Extra layer is printed to improve the conductivity

Resistance 15-16 Ohm (<40 Ohm needed)

SPG PlanoMesh screens are used to print thicker in one step while maintaining resolution

Stork Antenna DuPont 5025 + PV410

-5000

0

5000

10000

15000

20000

25000

30000

35000

40000

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Position (µm)

He

igh

t (n

m)

Profile measurement antenna 2 layers printed using woven mesh

Profile measurement antenna 2 layers printed using plano mesh

© Holst Centre

Results


• 3rd layer: dielectric

Al spikes in Silver should be covered

No pinholes allowed

Back scatter: White Silver; black dielectric Left Silver; right Silver+dielectric

Defect piercing dielectric

© Holst Centre

Results


• 3rd layer: dielectric

Depending on 1st layer, up to 4 layers needed to give optimal isolation

Pinhole in dielectric

Antenna silver lines

Cross section dielectric on Silver

Profile of antenna covered with dielectric

© Holst Centre

Results


• 4th layer: bridges

Challenge is to print high resolution lines on multi layer stack with >30µm step height

Printed 100µm lines on top of 2 layers of silver and 4 layers of dielectric

Dielectric

Silver bridges

Profile of printed silver bridges on top of silver and dielectric

© Holst Centre

Results


• 5th layer: printed resistors

• Results carbon resistors

Resistance accuracy < 5% within one sheet

Practical tests show that with a resistance ladder for 4 different pills pushed out all combinations can be correctly registered (DAC converter behavior)

Low value resistors have larger resistance than designed

A theoretical model was made and showed the same effect

The edges of the large carbon resistors have a relative larger contribution to the conductivity compared with small carbon resistors

© Holst Centre

Results

• Towards lower cost materials

Use printed copper for main circuit and bridges

Antenna is still silver to get the high conductivity needed

Working blisters were made

160°C processing temperature needed

Lifetime not yet good enough


Cross section Copper-dielectric-Copper Smart blister made of screen printed Copper

© Holst Centre

Results

• Current process suits for low volume production

High volume needs continuous production process


4 intermediate generations of smart blister

• Several working devices were made

Components on top Components in blister

Components in blister Components in blister

Final version of smart blister





3. Way of working

4. Results


6. Conclusions

7. Outlook

© Holst Centre

Towards high volume production

Transfer from S2S process to R2R process

• Flatbed screen printing Rotary screen printing

Similar process as flatbed screen printing

Circular formed mesh for continuous production


smallest feature size (lab)

40 m

smallest feature size (industrial scale)

100 m

ink viscosity range 100 – 80,000 mPas

wet layer thickness 12 – 500 m

dry layer thickness 500 – 50,000 nm

dry layer thickness accuracy

15 – 40 %

alignment/overlay accuracy

100 m

linear line speed >> 10 m/min, independent from resolution

http://www.storkprints.com/

© Holst Centre


Towards high volume production

Transfer from S2S process to R2R process

• Thermal sintering Photonic sintering

Selective heating through light absorption by the ink, not by the foil

High energy densities achieved by light focusing with an elliptical reflector

Pulsed light instead of continuous radiation to prevent excessive heating and substrate deformation Reflector geometry

Fast sintering (50 ms) of

development paste

3 flashes of 10 ms

Ref: Abbel et al., MRS Commun., 2012, 2, 145.

© Holst Centre


• Inline temperature and resistance measurement

The temperature profile reveals the change in material properties of the conductive ink. DuPont W693 (Ag development paste) on PEN

Photonic Sintering: Process study

Thermal conductivity: Low Heat capacity: High

Thermal conductivity: High Heat capacity: Low

Tg of PEN

© Holst Centre


• Entrapped solvents, bubbles and ablation

Top illumination: Shell formation

Short pulses: Not suited for drying

Fast heating: Entrapped solvents and exploding bubbles

Solvent evaporation: Back illumination and long pulses

High peak temperatures: Ablation due to polymer degradation

Process study

Shell formation Short pulses

Ablation (pre-dried ink) High peak temperature

Exploding bubbles Fast heating

50 x 50 x SEM, 100 x

© Holst Centre


• Sequence flash sintering (Silver np ink)

To achieve highly conductive structures without deforming the temperature-sensitive substrate, two flash settings are used

Process Time Temperature Pulse settings

Solvent evaporation seconds < Tg low intensity, high frequency

Sintering milliseconds >(>) 250°C high intensity, short pulse(s)

Using NIR pre-drying is a good alternative for the first stage

50x

Photonic sintering – process study

© Holst Centre


• Stand alone photonic sintering unit

Research tool to investigate sintering behavior of conductive inks

Elliptic shaped reflector to focus light

Inline resistance and temperature measurement (4-point)

Nitrogen atmosphere possible (copper inks)

• S2S photonic sintering unit

Research tool to upscale from single line to 30x30 cm

2 side illumination

Up to 10 lamps

Inline resistance and temp.

measurement (4-point)

Photonic sintering: Experimental setup (1)

Stand alone photonic sintering unit

© Holst Centre

Pit Teunissen, The IJC Dusseldorf, September 30, 2014

< 33

Novacentrix PulseForge 1300

Max radiant energy delivered

45 (J/cm2)

Curing dimension per pulse

75 x 150 (mm)

Max area cured per sample

300 x 150 (mm)

Capable of sintering copper materials

Particle based, complexes, oxides

Additional functionality developed at Holst

Inline measurement at 10,000 samples/s

Resistance

Temperature

Functionalities beyond sintering only

Photonic sintering: Experimental setup (2)

© Holst Centre

Rotary screen printing of functional structures: 3 layer stack

1st layer: Circuitry

2nd layer: Isolation

3rd layer: Bridges

Photograph of the R2R system containing the rotary screen printer and the sintering module

R2R rotary screen printing and in-line photonic sintering


R2R screenprint 3 layers aligned.mp4





3. Way of working

4. Results


6. Conclusions

7. Outlook

© Holst Centre

Conclusions


• Screen printing was demonstrated as a cheap manufacturing method for smart blisters

5 different layers were printed

Good conductivity

Overlay accuracy of ~100µm; even on multi-layer stack

Printed resistance ladders to monitor which pill is removed

Thinned down components integrated in foil

• Rotary screen printing in combination with NIR drying and photonic sintering was shown to be a way for high volume production





3. Way of working

4. Results


6. Conclusions

7. Outlook

© Holst Centre

Roll to roll inkjet printing

Printer: SPG inkjet printer

Print head: Xaar 1001

Material: Sun Chemical EMD5603

Foil: Agfa PET, 125 µm

Print speed: 10 m/min

Outlook processing


Movie: R2R Inkjet printing and sintering

Sintering module

NIR dryer

60% Power

Photonic sintering

2 lamps used;10Hz, 60% intensity

SPG R2R IJP on PET 10m_min.MOV

© Holst Centre

System in foil solution

Tutorial Hybrid Electronics – LOPEC 2014 (Munich) 26/05/2014

Storeskin

• shelve can detect spatially resolved presence of objects

• done by integration of a ‘large area pressure sensing foil’

• Only digital signals to outside world: more reliable

© Holst Centre

Skinpatch

• Wearable health application

• Demonstrated to work with monitoring skin temperature, humidity and movement

© Holst Centre

User interface design conference, April 1, 2014

Health patch

• Screen printed electrodes

• Disposable patch, reuse of electronics

• Stretchable electrodes for comfort

© Holst Centre

User interface design conference, April 1, 2014

Multi-functional printed sensor

• Sweat sensor

• Sensor measures ions (sodium, chloride); measure for dehydration

• More functionalities are under development

Pain relieve bandage

• For RSI patients

• Wearable electronics

• Stretchable and conformable printed circuit

• Integrated LED’s

© Holst Centre


Outlook application Storeskin

• shelve can detect spatially resolved presence of objects

• done by integration of a ‘large area pressure sensing foil’

• electronics external, hidden in box

• Luxury chocolate box with integrated light sensor and LED’s

• Upon opening the box, the light sensor activates the LED’s

• LED’s reveal location of origin of the chocolate

local printing company started doing explorative work on printed electronics after attending several workshops on this topic by Holst Centre and TNO

Thank you for your attention!

Documents

Printing Flexible Electronics for Health Care Applications