Development of a prototype system for judging product quality with ink whose color develops at different rates depending on temperature

May 11, 2021

Hitachi has developed an ink whose color develops at different speeds depending on surrounding temperature, which can be used to monitor the quality (freshness, deterioration, etc.) of food and pharmaceuticals. We have also developed a prototype system to create product management labels that combine the ink with an ID code containing product information, and judge the quality of the product based on the degree of ink coloration of the attached label. Using our proprietary digital color calibration technology, we have confirmed that it is possible to scan the ink color density to within a 1% margin of error in different lighting conditions. In the future, Hitachi will work with customers to promote practical uses of this technology. We also aim to apply it to our existing delivery business optimization solution^*1 and integrated value chain management platform.^*2 In this way, we hope to contribute to the realization of an environmentally friendly society with less product waste.

Background and issues addressed

• Food and medical supplies on the market are often discarded for various reasons, such as expiration or quality deterioration, but proper temperature control can prevent quality deterioration and reduce waste disposal
• Hitachi has already developed a temperature sensing ink^*3 that can detect abnormalities of temperature management of products, contributing to safe and secure quality control, but there have been issues with the accuracy of monitoring the temperature history
• Quality deterioration is mainly caused by chemical reactions such as decomposition, oxidation and polymerization, which are accelerated at higher temperatures. In order to monitor this deterioration, it was therefore necessary to develop an ink whose color develops more slowly at low temperatures and faster at high temperatures. It was also necessary to develop technology for precisely digitizing this change of color and linking it to product quality.
  

Developed technologies

• Design of ink formula whose color development speed varies depending on surrounding temperature conditions, which is in conjunction with deterioration of product quality
• High-precision digitization of ink color density enabled by label design and image data processing

Confirmed effect

• Smartphone’s built-in camera was used to take pictures of product management labels in various lighting conditions. By implementing digital color calibration, reading error of ink color density was reduced to within 1%, resulting high reading accuracy.

Published papers, conferences, events, etc.

• Introduced on WIPO GREEN, an online platform to promote the use of environmental technologies operated by WIPO^*4 https://wipogreen.wipo.int/wipogreen-database/articles/20511

Details of developed technology

1. Technology for the design of ink material whose color development time varies depending on temperature, which is linked to deterioration of product quality

The quality of food and pharmaceutical products deteriorates at a rate that grows exponentially with temperature. We have therefore developed a material whose color development reaction runs slower at low temperatures and faster at high temperatures so that its color is linked to the deterioration of products to which it is applied. Also, by uniformly dispersing this material in ink, we have achieved uniform coloration suitable for image reading.

2. Technology for high-precision digitization of ink color density by means of label design and image data processing

By printing four color samples around the ink applied to the label and correcting the RGB values^*5 extracted from the scanned image, it is possible to digitize the color density of the ink with high accuracy. Color change data acquired in this way can be linked with quality data obtained in advance, so that the quality of a product can be ascertained by scanning an image of the label. By managing this data in the cloud, information can be shared among stakeholders in the distribution process, from production to consumers.

*1

AI-based delivery business optimization solution: https://www.hitachi.com/New/cnews/month/2019/02/190228.html

*2

Platform for integrated management of cell and tracing information throughout the value chain for regenerative medicine products: https://www.hitachi.com/New/cnews/month/2020/08/200831.html

*3

Development of Ink that Detects Temperature Aberration for Safe and Reliable Quality Management: https://www.hitachi.com/New/cnews/month/2017/06/170627.html

*4

WIPO: World Intellectual Property Organization

*5

A set of three values representing the red, green and blue components of a color

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