Fabrication of complex shaped microparticles for self-assembly applications - Oluwatosin Omofoye

FABRICATION OF COMPLEX SHAPED MICROPARTICLES FOR SELF-ASSEMBLY APPLICATIONS

Oluwatosin Omofoye, C. Wyatt Shields IV, Gabriel P. Lopez

MOTIVATION

Assembly of colloids into distinct patterns is paving way of the future of materials science

Various applications in Photonic band gap materials Bio sensing materials

Opal is a natural photonic crystalhttp://opalux.com/

1

PART 1: FABRICATION

FABRICATION OF SHAPED COLLOIDS

Spin coat SU-8

2

2

1

Silicone wafer

3

Mask of Array

4

Expose UV light through Mask

5

Remove residual SU-8

6

Suspend in solution

Photolithography

EXTRACTION METHODS Using rubber scraper or a blade Sacrificial Layer (Omnicoat) below SU-8 Nano PG Remover Solvent

Silicone substrate

Sacrificial Layer

SU-8

Rubber PolicemanMaterial layers during fabrication 3

NANO PG REMOVER IMPROVEMENT10

um

Cyl

inde

rs5

um s

quar

es

PG Remover

4

Dry Extraction

EXAMPLES OF TILE PARTICLES

5um wide 0.5um thick square 10um wide 2um thick hexagons

5

PARTICLE MODIFICATION Fluorescence and Metal Deposition

Fluorescent Particles Gold/Cobalt Coated Particles

2 um thick hexagonal tiles

6

PART 2: ASSEMBLY

PREVIOUS ASSEMBLY TECHNIQUES

Electric Assembly

Magnetic Assembly

C. Shields IV, S. Zhu, Ye Yang, B. Bharti, J. Liu, B. Yellen, O Velev, G. Lopez. Soft Matter, 2013.

7

EVAPORATION INDUCED CONFINED AREA ASSEMBLY

1 2 3 4 5

An evaporation based form of assembly

G. Singh, S. Pillai, A. Arpanaei and P. Kingshott, Soft Matter, 2011, 7, 3290.

8

EVAPORATION INDUCED CONFINED AREA ASSEMBLY SEM Images of achieved patterns

G. Singh, S. Pillai, A. Arpanaei and P. Kingshott, Soft Matter, 2011, 7, 3290.

9

INITIAL RESULTS WITH SHAPED COLLOIDS

5um wide 2um thick cylinders

10um Cubes and 2um diameter cylinders

10um wide 2um thick squares 10um wide hexagonal prisms and 2um Particles

10

PROPOSED SOLUTION

Liquid – liquid interface method Assembly at interface of liquids with different

densities

11

CONCLUSION Successfully created a broad range of shaped micro-

particles Modified them to have metallic and fluorescent

properties Created self-assembled and active assembled

structures

12Magnetic field assembly of Metal coated Particles Passive assembly of shaped

particles

ACKNOWLEDGEMENTS LORD Foundation: Sponsor Dr. Gabriel Lopez: Lab Professor Wyatt Shields: Graduate Student Mentor SMiF (Shared Materials Instrumentation Facility) Peter Kingshott and University of Swinburne

(Research collaborators)

13

QUESTIONS?