ANFF-VIC Biointerface Engineering Hub

Spectroscopic ellipsometry is an optical characterisation technique used to determine the thickness of films. Polarised light is shined on the surface, reflected and received by the detector. The changes in polarisation also enable several other parameters to be determined, including roughness, crystalline nature, doping concentration and electrical conductivity.

At Swinburne, our ellipsometer can measure the thickness of films between 2nm and 3µm thick.

Dip coating is a process to deposit thin films from solution. The substrate is immersed and withdrawn from coating material at a constant speed. A large variety of films can be produced by using either self-assembly, sol-gel chemistry or layer-by-layer assembly.

Different properties of the film can be controlled by varying parameters such as the submersion time, withdrawal speed and number of cycles.

Plasma polymerisation is a technique for modifying the surfaces of materials by adding a thin film which possesses specific functional groups. This technique can produce alkanes, alcohols, acids, amine thiols, PEO-like and fluorocarbons. These functional films can vary the chemistry, charge and wettability of surfaces in addition to how they interact with various biological molecules such as proteins, cells and bacteria.

Plasma is produced by a glow discharge through an organic vapour. This is fragmented using radio frequency. The thickness, structure and surface functionalities of the film can be controlled by varying the plasma power, flow rate and deposition time.

Swinburne has six custom made plasma reactors, each designated for particular surface chemistries or applications. One of the reactors is heated, to enable the vaporisation of monomers with low volatility.

A Langmuir-Blodgett trough creates single molecule thick layers. The monolayer film is created by adding amphiphilic molecules to the surface of water, then compressing the film to the desired density. A surface can then be dipped into the substrate.

Quartz Crystal Microbalance (QCM) is used to analyse surface phenomena such as thin film formation, interactions and reactions.

The QCM sensor oscillates at its resonance frequency by alternating voltage. The frequency of the sensor decreases when mass is attached to the sensor. QCM can be used to measure the interactions of proteins, polymers, surfactants and cells with surfaces in solution.