Virtual Laboratory for Biomaterials: Processing and

CharacterisationBikramjit Basu

Department of Materials Science and Engineering,Indian Institute of Technology Kanpur, INDIA.

*E-mail: bikram@iitk.ac.in

Broad objectives:

• To design five web-based interactive experiments in the broad area ofmanufacturing/fabrication of Biomaterials.•To excite the students remotely in the emerging area of Biomaterials.•To enable sharing of highly costly equipments like spark plasma sintering as well as somestate-of-art cell culture and bacteria culture facilities with other institutions remotely.

Experiments originally proposed in the proposal: Super fast densification of Biomaterials Biological cell interaction with a material How a material can be anti-bacterial? Influence of external electric field on the cell-material interaction Inhibition of bacterial infection on implants by magnetic field

Virtual Laboratory for Nanocomposite Fabrication

and Biomaterials LaboratoryCurrent Status - experiments completed / under progress:• Video of Biomaterials fabrication using spark plasma sinteringcompleted

• All the required files on the fundamentals of Nanocompositefabrication as well as cell-material interaction in the contest of thebiomaterial application are uploaded on VLFM website maintained atIIT Kharagpur

• Planning of bacteria culture to show bactericidal /bacteriostaticproperty in magnetic field

• Cell culture experiments in electric field experiments to beperformed

Schedule of meetings with the DNCs: December, 2010 in IIT Kharagpur

Ceramics Biomaterials research

Spark Plasma Sintering (SPS) UV Spectrophotometer

Compression molding CO2 incubator

3D Printing to fabricate materials

with designed structure

Phase contrast microscope

High temperature furnaces Ultra low deep freezer

Fretting wear tester Critical point dryer

Laser surface Profilometer Pulse Electric field set up

Dynamic Elastic Modulus

analyzer

Shaking incubator

Bacterial cell incubator

Facilities developed at IIT Kanpur

Research Facilities

Spark Plasma Sintering facility

Cell Culture facility

Bacteria culture facility

Some background on Spark Plasma

Sintering

(MOVIE uploaded on website)

Spark plasma sintering (SPS)

Initial activation of powders by pulsed voltage.

Resistance sintering under pressure.

Heating rate: upto

600K/min.

Sintering temperature

lower by 200-3000C.

Holding time 0-10 min.

Total processing time:

20 min.

Benefits:

Reduced sintering

time.

Good grain to grain

bonding.

Clean grain

boundaries.

Phenomenology of SPS:- release of electrical energy through a porous powder compact

- breakdown of surface films

- Arcing at pores leading to enhanced mass transport to neck

Experimental: Spark Plasma Sintering

Heating rate : 600 – 650 K/min; Maximum pressure: 50-60 MPaDC Voltage : 5 – 10 V; Pulse frequency: 30-40 kHZVacuum: 60-70 mtorr; Sintering time: 5 minutes

SPS effect

Simultaneous application of mechanicalpressure and high power pulse source (upto 6kA).

Pulsed direct current leading to cleaning andsurface activation of powders.

Generation of electric discharge at the neckregion

In the presence of pressure and electric current, localized

necking occurs faster due to joule heating. Consequently, the

temperature raises very fast (faster than conventional sintering and

Hot pressing) and the densification is completed within few minutes.

Neck formation due to localized heating

Joule’s heating: localized

temperature increment

Groza et al., UC Davis

Three mechanisms may contribute to field assisted sintering:

activation of powder particles by pulsed current

resistance sintering

pressure application

This activation is unique and provides main difference from

more conventional resistance sintering processes (hot pressing).

The surface activation results in clean grain boundaries. The

grain boundary area shows direct grain-to-grain contact, which

is attributed to the physical activation of powder particle

surfaces during pulsed current application i.e. enhanced grain

boundary diffusion process.

SPS process

Multi-Stage Spark Plasma Sintering: Novel

technique to obtain enhanced mechanical and

triblogical properties of ceramics

Results of some Recent Experiments

Single stage SPS vs. Multi stage SPS

1 surface cleaning /activation

2 grain boundary diffusion

3 Lattice diffusion

900oC, 5 min

1100oC, 5 min

1200oC, 5 min

MSS

900oC, 5 min

1200oC, 5 min

TSS

Initial experiments to test hypotheses with α-Al2O3

1200oC, 5 min

SSS

Densification parameter vs time

• MSS: Densification is completed almost at the onset of final

stage of holding

• SSS/TSS: A relatively monotonic increase in Ψ value during

heating to sintering temperature

Ψ=(ρt-ρi) / (ρth-ρi)

ρt :instantaneous density

ρi :initial density

ρth: theoretical density

Subsurface Hardness

• SSS: Hardness decreases towards centre: non uniform densification

• MSS: Uniform hardness

15 mm

K. Madhav Reddy, Nitish Kumar and B. Basu; Scripta Materialia (in Press, 2009).

Microstructure

(i) SSS shows Porosity

(ii) TSS Bimodal distribution – (250-500nm)

(iii) MSS Unimodal distribution (iv) TEM grain size ( 200-300nm)

100nm

(iv)

Further experiments with zirconia

980oC, 5 min

1100oC, 5 min

1250oC, 5 min

MSS

980oC, 5 min

1250oC, 5 min

TSS

1250oC, 5 min

SSS

XRD Phase evolution for Zirconia Consolidated

(a) Initial Powder (b) SSS (C) TSS (d) MSS

Ψ= (ρt-ρi) /(ρth-ρi)

ρt is instantaneous density,

ρi is initial density

ρth is the theoretical density

Zirconia (ZrO2 )

Subsurface Hardness

● In SSS/TSS hardness

decreases with distance

from edge towards centre

● MSS hardness is uniform

along the pressure direction

as well transverse direction

15 mm

TEM micrograph of ZrO2

(a) SSS

(b) MSS

Grain size: 60-250 nm

Grain size 70-120nm

Sintering

Schedule

Relative

density(ρ)

Vickers

hardness

(100g)

Fracture

Toughness

( 2kg)

3-point

Flexural

Strength

SSS 98.9 13.6 0.2 5.22 0.14 619± 50

TSS 99.3 15.6±0.4 5.1±0.3 1093± 35

MSS 99.5 15.9 0.3 6.6 0.06 1350 ± 65

The summary of the research of tetragonal Zirconia

Superior and more uniform hardness/toughness/strength properties

and also better density values at identical final sintering temperatures

Uniform densification and avoid of grain growth during MSS

Biomaterials: Importance,

processing and characterization

MOVIE ON CELL CULTURE

uploaded

MOVIE ON BACTERIA CULTURE

uploaded

How to Synthesize Ca10(PO4)6(OH)2 – hydroxyapatite

powders in a laboratory?

Cell culture

Notes on protocol is provided in separate document

Cell Culture experiment

Electric-field stimulated cell adhesion

Electric Field Pulse Generator

(a) 0 V, (b) 1 V, (c) 2V, (d) 10 V

0 V 1 V 2 V 5 V 10 V 15 V 20 V 25 V0.0

2.0x103

4.0x103

6.0x103

8.0x103

1.0x104

1.2x104

1.4x104

1.6x104

1.8x104

2.0x104

2.2x104

2.4x104

2.6x104

**

*

**

*f = 100 Hz

d = 4 %

No

of

ce

lls

/cm

2

Voltage (V)

(b)

*

Influence of E-field strength on cell viability (control disc)

Optimal E-field = 0.66 V/cm

Antimicrobial property evaluation

Notes on protocol is provided in separate document

E. coli bacteria

(a) Control,

(b) HAp -20 wt. % ZnO

S. aureus bacteria

(c) Control

(d) HAp-20 wt. % ZnO

Human Osteoblast-like

cells SaOS2

(e) Control

(f) HAp -20 wt. % ZnO

An example of material with antimicrobial property:

Conventionally sintered HA–ZnO

(a)

(d)

(b)

(c)

(e)

(f)(e) (f)

(c) (d)

Basu and co-workers; J. Biomedical

Materials Research B (2010)

30

Schematic diagram of electromagnet and magnetic field set up used in our study

Magnetic field exposure cycle on bacteria suspensions

Time

2hrs. 4 hrs.

100 mT

0 mT

100 mT

0 mT

120 min

30 min

60 min

240 min

Time

2hrs. 4 hrs.

100 mT

0 mT

100 mT

0 mT

Time

2hrs. 4 hrs.

100 mT

0 mT

100 mT

0 mT

120 min

30 min

60 min

240 min

Log phase starts

Lag phase

Antibacterial efficacy of electromagnetic field

(bar = 10 µm, magnetic field strength =100mT)

Control (0 min)

Control (60 min)

HA surface (0 min)

HA surface (120 min)

Acknowledgements: Funding agencies

Department of Science and Technology (DST), India

Council of Scientific & Industrial Research (CSIR),India

Department of Biotechnology, DBT, India

IIT Kanpur CARE grant

Acknowledgements: Students, Post-doc

MaterialsA. MukhopadhyayK. Madhav Reddy

Alok Kumar

CeramicsShekhar Nath

S. BodhakN. Saha

A. R. Molla

Physics/ChemistryAshutosh K. Dubey

B. SinghS. KumarV. Raju

PolymerDr. Garima Tripathi

BiologySushma KalmodiaHemant Kumar

Acknowledgements: Students, Post-doc

Materials

A. Mukhopadhyay

K. Madhav Reddy

Alok Kumar

Ceramics

Shekhar Nath

S. Bodhak

N. Saha

A. R. Molla

Physics/Chemistry

Ashutosh K. Dubey

B. Singh

S. Kumar

Polymer

Dr. Garima Tripathi

Biology

Sushma Kalmodia

Amit Nayak

Acknowledgements: Collaborators

Materials

K. Biswas

(IIT Kanpur)

Mathematics

/Statistics

M. Banerjee

(IIT Kanpur)

In-Vivo Testing

M. Mohanty

P. V. Mohanan

(SCTIMST,

Trivandrum)

Physics

R. Gupta

(IIT Kanpur)

Materials

K. Biswas

(IIT Kanpur)

Biology

Alok Dhawan

(IITR, Lucknow)

Medical Professionals

Dr. Amit Dinda (AIIMS)

Lt. Col. Manish Mukherjee

(INMAS, DRDO)