Hoxley - Biosensing applications of wide bandgap semiconductors
I am interested in semiconductor crystal surfaces, particularly diamond, and how they react to the world around and within us. By coating these surfaces with organic and metallo-organic compounds and observing the change their electrical and optical properties, we can use them to engineer implantable biosensors for medical assays.
I am also deeply committed to the dissemination of knowledge through teaching, which I regard as a process of institutionalised coaching. This extends to research into ways of making this coaching possible (and efficient) in a mass tertiary education system, primarily through combining the modern educational psychology with information technology. I work extensively with the secondary school system, particularly in ways of linking science-as-practiced with contemporary classroom practice through reconceptualising initial teacher education programs.
Research areas
Towards implantable diamond biosensors
The field of implantable biosensors is progressing at a cracking pace, for good reasons. Continuously monitoring the bodies of patients allows them to receive the best possible treatments. Doing so outside the hospital environment offers the best quality of life (and significantly reduces treatment costs). These projects explore a big challenge: how to functionalise a biocompatible surface so that it is selective, sensitive, stable and long-lived. Diamond is highly stable and biocompatible, but as an emerging electronic material, much remains to be known about crafting working devices.
Mesoscale electronic circuits in diamond. The diamond surface can be made conductive by adsorbing hydrogen. We use an Atomic Force Microscope to 'draw' electrical pathways and devices in areas less than the width of a hair.
Laser-induced conductivity of functionalised diamond surfaces. An implantable biosensor should have no wires breaking the skin. But how then to get power in and information out? The student will investigate how pulsed lasers can be used to interface with the biosensor through the skin.
Bio-activation of diamond surfaces. The diamond is famously chemically inert, the key to its biocompatibility. Amine and carboxyl chemistry can be used to attach and interact with biological molecules, for example antigens and proteins.
Osmotic gradients in chicken eyes. Putting an electronic device in the body is complicated by the electrochemical environment. We can understand this by analysing how changes in ionic balance affect chicken eyes, which offer a useful platform for testing prototype biosensors.
Electrical properties of nanostructured surfaces
Photovoltaics have moved well beyond silicon solar cells, promising ever greater harvesting of energy from our nearest fusion reactor, the sun. Both organic and inorganic approaches require careful understanding of the nanoscale electrical properties of the films at the interface layers. The Atomic Force Microscope in electrical characterisation modes can be used for this, and combined with macroscopic techniques to relate the effects at different lengthscales.
Conductivity of Ag Nanowires. Silver is a popular material amongst nanotechnologists, and ultra-narrow wires can be grown with minimal effort. The properties of these wires is of great interest, particularly when heated. This project will be done in collaboration with Daniel Langley.
Electrical characterisation of ZnO nanostructures. Many advanced inorganic photovoltaics rely on an ultrathin zinc oxide structures to get charge out of the device. These structures need to conduct electricity in just the right way. The student will characterise a range of ZnO nanostructures grown by collaborators to give feedback into optimising growth recipes.
Electrochemistry of Pyrite under fluids. Pyrite is an abundant natural semiconductor with, theoretically, very good photovoltaic properties. In practice, defects and surface effects are a barrier to working devices. This project will attempt to work out what these effects are, and how to get around them. Along the way, it may shed some light on how to combat acid mine drainage, a very significant environmental problem.
Sarah Becirecic Laena D’Alton (co-supervisor, with Conor Hogan, LIMS) Paul Di Pasquale (co-supervisor, with Chanh Tran, LIMS) Michael Munforte (co-supervisor, with Danny Ortenyo, University of Melbourne) Daniel Roberts Steve Yianni (co-supervisor, with Chris Pakes, LIMS)
Group leader