| CPC G01N 21/78 (2013.01) [A61B 5/0059 (2013.01); C25D 11/022 (2013.01); C25D 11/08 (2013.01); C25D 11/10 (2013.01); C25D 11/22 (2013.01); G01N 21/45 (2013.01)] | 24 Claims |

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1. A thin film optical interference apparatus for detecting the presence of a target compound, the apparatus comprising:
a single layer of an anodizable metal, the layer having a first portion that is anodized to form a porous metal oxide and a second portion that is non-anodized underlying the first portion; wherein
the first portion of the layer comprises a first thickness and a first refractive index generating a first optical path length,
the second portion of the layer comprises a second thickness and a second refractive index generating a second optical path length;
wherein the second optical path length is different than the first optical path length providing a first interference colour, and
a non-anodized metal electrodeposited on the porous metal oxide providing an enhanced interference colour compared to the first interference colour; and
wherein upon binding of the target compound to the apparatus, a third thickness and a third refractive index generates a third optical path length, the third optical path length being different than the first and second optical path lengths, resulting in a detectable change in interference colour indicative of the presence of the target compound.
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