Lars Pleth NielsenDanish Technological InstituteTribology Centre

New and novel coatings for medical applications

– an introduction to Physical Vapour Deposition (PVD) with examples of passive and active coatings relevant for medical applications

Klaus Pagh Almtoft, Henrik Bækgaard,

Bjarke Hall Christensen, Jona Jacobsen, Helle Iben Jensen,

Christian Slot Jeppesen, Lone Larsen, Jens Erik Lionett,

Sascha Louring, Claus Mathiasen, Dorthe Kjær Pedersen,

Preben Munch Pedersen, Kristian Rechendorff,

Henrik Horup Reitz, Martin Simonsen, Jens Vestergaard

Outline

Introduction to surface coatings

Introduction to Physical Vapor Deposition (PVD) The technique Our equipment

Examples of coatings for medical applications Porous TiN for novel electrodes Low friction diamond-like carbon (DLC) coating for dental applications Strontium releasing coatings accelerating bone growth

Conclusion - summary

Advanced Surface Technology

Per Møller, Lars Pleth Nielsen

ISBN 978-87-92765-23-9

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Danish Technological Institute

Tribology Centre

More than 25 years of experience in coatings

17 employees + 6 students

Last year we coated 234.000 items

60% on production / 40 on R&D

Definition of Tribology:

It is the science and engineering of interacting

surfaces in relative motion. It includes the study and

application of the principles of friction, lubrication and

wear.

Danish Technological Institute

Introduction to surface coatings

Introduction to Physical Vapor Deposition (PVD) The technique Our equipment

Examples of coatings for medical applications Porous TiN for novel electrodes Low friction diamond-like carbon (DLC) coating for dental applications Strontium releasing coatings accelerating bone growth

Conclusion - summary

Advanced Surface Technology

Per Møller, Lars Pleth Nielsen

ISBN 978-87-92765-23-9

Introduction to surfaces coatings

Surfaces are extremely important

Surfaces are important – decorative

Surfaces are important – decorative

Low friction surfaces

Hard surface - Chromenitride

How do we select coatings?

CVD (Chemical Vapour

Deposition)

Organic coating

Electroplating

Thermal sprayed

coatings

PVD (Physical Vapour

Deposition)

Cladding

Hot dip

galvanizing

Vitreous enameling

Ion implantationNitriding Electroless plating

Anodization

PVD (Physical Vapour

Deposition)

Introduction to Physical Vapor DepositionA vacuum based process

PVD

Thin film processes

Fysiske processer

Kemiske Processer

Termiske processer

Sputtering

Plasma CVD

Termiske CVD

Laser

Vakuum Fordampning

Ionized cluster beam deposition (ICBD)

Activated reactive evaporation (ARE)

Ion Platering

Molecular Beam Epitaxy (MBE)

LASER CVD

Chemical Solvent

Simpel DC sputtering

Magnetron sputtering

RF sputtering

Dual magnetron sputtering

Ion processer Implantering

IBAD-proces

Plasma nitrering

Reaktiv sputtering

Materialedivisionen

TRIBOLOGICENTER

Thin film processes

Fysiske processer

Kemiske Processer

Termiske processer

Sputtering

Plasma CVD

Termiske CVD

Laser

Vakuum Fordampning

Ionized cluster beam deposition (ICBD)

Activated reactive evaporation (ARE)

Ion Platering

Molecular Beam Epitaxy (MBE)

LASER CVD

Chemical Solvent

Simpel DC sputtering

Magnetron sputtering

RF sputtering

Dual magnetron sputtering

Ion processer Implantering

IBAD-proces

Plasma nitrering

Reaktiv sputtering

Vacuum Chamber – controlled atmosphere

-

+

Raw material

Working plasma

Items to be coated

What is a plasmaDefinition: Plasma is a distinct phase of matter,

separate from the traditional solids, liquids,

and gases.

It is a collection of charged particles that

respond strongly to electromagnetic fields,

taking the form of gas-like clouds or ions.

The particles in a plasma are electrically

charged (formed by stripping electrons), it

is frequently described as an "ionized gas“.

Plasma was first identified (as

"radiant matter") by Sir William

Crookes in 1879.

Sir J.J. Thomson identified the nature

of the matter in 1897.

It was Irving Langmuir who assigned

the term "plasma" in 1928.

Plasma is actually the most common

phase of matter. Flame, lightning,

interstellar nebulae, stars, and even the

empty vastness of space are all examples

of the plasma state of matter.

What is a plasma

Materialedivisionen

TRIBOLOGICENTER

Sputtering

Plasma e.g. Ar+

Cathode of the raw material

Sputter yield =Atoms removed

Incoming ions

Materialedivisionen

TRIBOLOGICENTER

Sputter yield

Sputter yield =

What does it depends on?

Type of incoming atoms (the plasma)

Type of atoms in the target

Incoming energy

Incoming angle

Atoms coming out

Atoms coming in

Materialedivisionen

TRIBOLOGICENTER

Sputter yield; Ar versus Ne

Op in mass (Ne to Ar) -> Sputter yield increases

Morphology of films

vs. energy of bombarding ions

90 V

60 V

45 V

30 V

Floating

TiO2 morphology

Increased Ar ion energy, Bias

5 x PVD units

• 4×Targets:

• DC sputtering

• Bias: DC or RF supply

and samples

• 6 towers

• 4×Targets:

• DC or pulsed-DC

• Bias DC, MF or RF

• 6 towers

• 6×Targets:

• DC or pulsed-DC

• Bias: DC, MF or RF

• HiPIMS

• Bias: HiPIMS

• 6 towers

• 4×Targets

• DC sputtering

• Bias: DC, MF

• 10 towers

5 x PVD units

• 4×Targets:

• DC sputtering

• Bias: DC or RF supply

and samples

• 6 towers

• 4×Targets:

• DC or pulsed-DC

• Bias DC, MF or RF

• 6 towers

• 6×Targets:

• DC or pulsed-DC

• Bias: DC, MF or RF

• HiPIMS

• Bias: HiPIMS

• 6 towers

• 4×Targets

• DC sputtering

• Bias: DC, MF

• 10 towers

Vacuum Chamber

-

+

Raw material

Working plasma

Raw material: Ti

Working plasma: Ar Coating Ti metal

Raw material: Ti

Working plasma: Ar/N2Coating TiN ceramic nitride

Vacuum Chamber

-

+

Raw material

Working plasma

Raw material: Ti

Working plasma: Ar Coating Ti metal

Raw material: Ti

Working plasma: Ar/N2Coating TiN ceramic nitride

Materialedivisionen

TRIBOLOGICENTER

Sputter TiAlN

+ =

+ = TiAlN

mix

Ti Al

TiN – this is an old workhorse

Materialedivisionen

TRIBOLOGICENTER

TiN; an old workhorse for tools

TiN – this is an old workhorse

High surface area conductive electrodes

High surface area – conductive electrodes

TiN

Si

2-20 µm

”Changing deposition

parameters can have a

large effect on the coating

morphology”

High surface area – conductive electrodes

Reference TiN

Highest N content

Thicker TiN coating (x2)

High surface area – conductive electrodes

Göttingen minipig

High surface area – conductive electrodes

High surface area – conductive electrodes

High surface area – conductive electrodes

1) Electrode Contact

2) Lead

3) Electrode Body

4) Electrode Tines.

Microstructures on the PEEK body and the silicone tines to

accelerate and improve tissue integration

High surface area – conductive electrodes

Low-friction coatings for dental applications

Low frinction DLC to dental applicaiton

Reactive DC magnetron sputtering

Deposition parameters:

Cr to make CrN adhesion layer

C to make a low-friction top layer

Ar/N2

Deposition temperature ~180-200 °C

Thickness ~ 3 µm incl. adhesion layer

SubstratesTargets/

cathodes

Low frinction DLC to dental applicaiton

Robertson 2002

~10 million patients per year

Dental implants

~10 million patients per year

~10 % experience issues with peri-implantitis (bacteria,

vibrations..)

Bad mouth smell

Dental implants

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0,50

Ti-Ti Ti-DLC(ambient)

Ti-DLC (wet) Ti-MediCarb(ambient)

Ti-MediCarb(wet)

Friction c

oeffic

ient

Seunghwan Lee (DTU-MEK)

Applied a fixed Torque [M1]

F should be as high as

possible for fixed Torque

[M1]

Titanium against titanium is very bad

Titanium substrate Titanium substrate

CrN adhesion Ti adhesion

a-C toplayer

Coatings

a-C toplayer

Hydrogen free – no hydrogen embrittlement

Coatings

Applied a fixed Torque [M1]

F should be as high as

possible for fixed Torque

[M1]

Average of; 1st, 2nd and third tightening

Tighting force – fixed momentum

160

180

200

220

240

260

280

300

320

340

360

0 1 2 3 4 5

[Force] Pre-load at 25 [Ncm]

Old design

Old design + coating

New design

New design

+ coating

Low-friction drills

Low-friction drills

Sr-Ti coating for accelerated bone growth

Why Sr?

Substitutes for Ca in mineral phase of bone

Stimulates bone formation

Reduces bone resorption

Shown anti-inflammatoric effect

Sr is used via strontium ranelate as treatment for osteoporosis

Sr in the surface of an implant gives local effect where needed

Park, J.-W. et al.; Acta Biomaterialia (2010) 6(7); pp. 2843.

Roy, M. M. et al.; J. Biomed. Mat. Res. Part A (2012) 100(9);

pp. 2450.

Xin, Y. et al.; ACS Nano (2009) 3(10); pp. 3228.

Beneficial effects for accelerated and

increased implant osseointegration.

General healing times are 2-4 month

before placement of the prostheses

Coated

surface

The dynamic structure of bone

Constant remodeling – ”new” skeleton every 10 years

Sr ”negative” effect on OC - ”positive” effect on OB

Riggs and Parfitt;

J. of Bone and Mineral Research,

2005

A sufficient amount of Sr must be released from the implant surface to stimulate the

formation of bone around the implant

No delamination of particles from the surface can be accepted

Coating synthesis

DC magnetron sputtering

Industrial coating unit (CC 800/9 SinOx)

Deposition parameters

Co-sputtering of Ti target (Grade 1) and

Ti-Sr-O target (99.9%), 88mm x 500mm

Sr content 0 - 10 at.%

Argon sputtering gas

Deposition temperature ~ 100°C

Pressure ~ 0.4 – 2.4 Pa

Deposition rate ~ 240 nm/hr

Substrates (rotating): Silicon wafer,

titanium implants, steel, …

Coating characterization

Morphology (SEM), chemical composition (XPS, RBS), crystal structure (XRD)

Substrate

Sr-Ti-O

Ti adhesion layer

Sr release: wash-out in PBS solution + inductive coupled plasma optical emission spectroscopy (ICP-OES)

Bending test of Sr-Ti-O coated Ti rod – no delamination

Adhesion tests by screwing implants into polyoxymethyl (POM)

1 2 3 4 5 6 70

1

2

3

4

5

6

7

7.0 at.%

5.3 at.%

4.4 at.%

Sr

rele

ase (g/c

m2)

Days

Sr release vs. Sr concentration

1 2 3 4 5 6 70

1

2

3

4

5

6

7

7.0 at.%

5.3 at.%

4.4 at.%

3.6 at.%

2.9 at.%

2.3 at.%

1.1 at.%

Sr

rele

ase

(g

/cm

2)

Days1 2 3 4 5 6 7

0

1

2

3

4

5

6

7

7.0 at.%

Sr

rele

ase

(g

/cm

2)

Days1 2 3 4 5 6 7

0

1

2

3

4

5

6

7

7.0 at.%

5.3 at.%

Sr

rele

ase

(g

/cm

2)

Days

Sr-Ti-O on Si wafer

1 2 3 4 5 6 70

1

2

3

4

5

6

7

7.0 at.%

5.3 at.%

4.4 at.%

3.6 at.%

2.9 at.%

2.3 at.%

Sr

rele

ase (g/c

m2)

Days20 30 40 50 60

¤*

*

*

7.0

5.3

4.4

3.6

2.9

2.3

Inte

nsity (

a.u

.)

2 (deg)

At.%

1.1

*

¤

= 2 deg* : hex. Ti/ TiO

x

¤ : fcc TiOx

Si

Sr release vs. coating thickness

At.%: Sr 4.4; Ti 35.6; O 60.0

Pressure 1.1 Pa

Increased Sr release vs. thickness

Thickness + porosity larger effective area

1 2 3 4 5 6 70

1

2

3

4

5

6

1500 nm

1000 nm

200 nm

50 nm

Sr

rele

ase (g/c

m2)

Days

Sr-Ti-O on Ti rods

250 nm

300 nm

735 mPa

300 nm

2380 mPa

Sr release vs. pressure

At.%: ~ Sr 4.5; Ti 37; O 58.5

Thickness 650 – 900 nm (high pressure

lower thickness due to gas collisions)

Increased porosity (more/thinner columns) with higher pressure

2380 mPa

500 nm735 mPa

500 nm1 2 3 4 5 6 7

0

1

2

3

2380 mPa

1550 mPa

735 mPa

Sr

rele

ase

(g

/cm

2)

Days

Sr-Ti-O on Si wafer

Sr-Ti-O coatings

Sr-release profile can be tailored by deposition parameters

Coating thickness, deposition pressuer, Sr concentration

1 2 3 4 5 6 70

1

2

3

4

5

6

7

7.0 at.%

5.3 at.%

4.4 at.%

3.6 at.%

2.9 at.%

2.3 at.%

1.1 at.%

Sr

rele

ase (g/c

m2)

Days

Do Sr-Ti-O coatings improve

implant osseointegration?

1 2 3 4 5 6 70

1

2

3

2380 mPa

1550 mPa

735 mPa

Sr re

leas

e (

g/cm

2 )

Days

In vivo model

In vivo model

In vivo model

O. Z. Andersen et al., Biomaterials, 34 (2013) 5883-5890.

V. Offermanns et al., International Journal of Oral and Maxillofacial Surgery, 42(10) (2013) 1183

V. Offermanns et al., J Biomed Mater Res Part B, 103 (2015) 1099-1106.

Tested in rats and rabbits

Conclusion - summary

An introduction to surface coatings

An introduction to Physical Vapor Deposition (PVD)

Examples of coatings for medical applications Porous TiN for novel electrodes Low friction diamond-like carbon (DLC) coating for dental applications Strontium releasing coatings accelerating bone growth

Advanced Surface Technology

Per Møller, Lars Pleth Nielsen

ISBN 978-87-92765-23-9

We would like to invite you to collaborate with us

Lars Pleth Nielsen, Director

Tribology Centre, Danish Technological Institute

Email: lpn@dti.dk

Phone: +45 72201585

In the Bioneca COST action we are already cooperation with:

• University of Malta

• University of Eastern Finland

In a privous COST action:

• Nicolaus Copernicus University