We want to present an optical thin film sensor chip able to detect the decay of food through a specific color change. The design of the chip relates to a phenomenon, the so called “anomalous absorption”, which can best be described as a surface enhanced reflectivity. If a metal cluster film is positioned in a well defined short distance to a smooth metal surface it can be observed that the minimum of spectral reflectivity strongly depends on the thickness of the interlayer: This absorbing thin-film positioned at a defined distance to a metal mirror represents a special kind of reflection interference filter. As a result of this effect a thickness change of an interlayer between mirror and cluster layer will be visible upon illumination with white-light by an altered color impression of the reflected light. In such a sensor setup we integrated a polymer which is biodegradable by the same enzymes and in the same time as food decay will happen. The degradation of the polymer results in reduction of the film thickness and thus in a specific change of the color.
Journal: TechConnect Briefs
Volume: 2, Technical Proceedings of the 2007 NSTI Nanotechnology Conference and Trade Show, Volume 2
Published: May 20, 2007
Pages: 504 - 507
Industry sector: Sensors, MEMS, Electronics
Topics: Biomaterials, Chemical, Physical & Bio-Sensors