Disposable colorimetric geometric barcode sensor for food quality monitoring

In this work, we present a disposable paper-based optical sensor arranged as barcode for monitoring food spoilage. The color-changing barcode is embedded in the food packaging and monitored using smart phone. The color change of different optical sensing dyes that make up the barcode is due to the emission of volatile organic compounds (VOCs) from food. Different geometric shapes are assigned to each sensing dye for identification. The sensor fabrication is low-tech and easy to perform. A smart phone quantifies the color change in the barcode food sensor, which provides a non-contact metric of food freshness/spoilage.