Oxygen Sensing MineralsDr Nuno Faria and Prof Jonathan Powell

Medical Research Council

Cambridge UK

Challenge sponsored by:

The Technology

• We have developed and patented an

oxygen sensor technology based on a

cheap, scaleable modification of

mineral structures

• Our oxygen sensors can provide an irreversible colour

change and can be incorporated into a variety of

settings

Key Features

•Clearly indicates changes- Colour change upon oxygen exposure is striking

• Colour, composition, oxygen sensitivity can all be tailored to meet specific requirements

- Minimum exposure time required for a colour change can be adjusted from a few minutes to several days.

- Many possible colour combinations

•Accurate and effective- Sensitivity can be adjusted to different oxygen levels as required per specific

application

• Can be incorporated within various materials during its manufacture

• Low cost- Synthesis is a one-step aqueous process that uses cheap reagents commonly used in

the food industry; manufacturing process is easily scalable

• Safe for contact with food

• The sensors are composed of metal oxide particles, which have

been modified by incorporating organic molecules (ligands) during

manufacture

• The type of metal and ligand as well as size and crystallinity of

particles can be tailored to achieve specific properties

• The metal is present in its reduced state. Exposure to oxygen

oxidizes the metal ions, resulting in a colour change of the

particles.

• Particles can be incorporated into various materials (e.g. gels,

paper, plastic).

The Material

Tailorable with different ligands

+O2

- O2

Ligand Mix A Ligand Mix B

The incorporation of different ligands into the mineral can be

used to tailor the colour shift and reactivity to oxygen.

Various mineral phases can be produced

+O2

- O2

Mineral Phase I Mineral Phase II

A range of mineral phases can be synthesised. These differ considerably in their composition and physicochemical properties.

Nanoparticulate sensors

Before

oxygen

exposure

After

oxygen

exposure

A B C D E F G H I

- Can be produced as stable colloidal suspensions

- Can spray-dried onto surfaces (e.g. packaging materials)

- As with the sensors in a solid matrix (previous slides), altering the synthesis conditions (sensors A-I) results in distinct colour shifts

Sensors present as particles in suspension

Manufacturing

• Low production costs- Low cost reagents used

- One-step synthesis at room temperature

- No solvents required

• Straightforward scale-up-Preliminary syntheses have already been carried out by a manufacturing CRO

• Easy incorporation into various materials (e.g. packages)- Particles can be easily spray-dried or coated onto everyday materials (paper, gels etc)

• Does not need expensive sensing equipment

• Colour change can be reversible or irreversible

• Does not bleach upon exposure to light

• Safe- Existing sensors are built from materials that should not be ingested

- Our sensors are ‘assembled’ from GRAS reagents used in the food industry

• Cheap- Aqueous synthesis that uses inexpensive reagents

Summary