Laser-induced carbon nanostructures

A method of producing a food testing sensor electrode, comprising the steps of:

• (a) using a first laser beam configured to irradiate an encapsulated, sub-surface region of a carbon pre-cursor material below a surface of the carbon pre-cursor material, parameters of the first laser beam being selected to create carbon foam in that encapsulated, sub-surface region and a carbon-based material above the carbon foam;
• and
• (b) using a second laser beam configured to remove or ablate the carbon-based material sitting above the carbon foam, parameters of the second laser beam being selected to expose or alter at least some of the carbon foam, to produce a resultant carbon foam material;
• and
• (c) functionalising the resultant carbon foam material by adding a receptor or recognition element that is specific to a target or analyte to the resultant carbon foam material or a linker that is attached to the resultant carbon foam material;
• (d) providing the functionalised carbon foam material for use as a sensor electrode in an assay device, configured for food testing.