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Research & Development

Ink can act as a temperature sensor. Based on such an idea, Hitachi is working on developing services to innovate temperature control in logistics processes. By using an ink that indicates any aberration from controlled temperatures by changing color, with a smartphone – a readily available device, anyone can now determine the temperature control status of products at a glance. As a result, it is possible to maintain consistent control of individual products from production to consumption. We interviewed two researchers who are working to develop services from the customer perspective to realize "a world where the quality of logistics can be seen."

Photo: KAWASAKI Masahiro
Senior Researcher

Photo: AIDA Kohhei
AIDA Kohhei

(Publication: August 27, 2018)

An ink that changes color with temperature

We understand that you have developed an ink that changes color with temperature.

Photo: AIDA Kohhei

AIDAYes, the "temperature detecting ink" has a characteristic where its color is constant when the ambient temperature is maintained within a set temperature range, but changes if the temperature should exceed the upper or lower limit. It is a notable feature of this thermochromic ink as it not only detects when the temperature goes above the upper temperature limit but also when it falls below the lower temperature limit. Moreover, this process is irreversible once the color changes even if the temperature is brought back to within the control range. As a result, any aberration from the temperature control range leaves a trail as a color change.
The temperature range of the thermochromic ink can be set for any even value (every 2℃) between -20℃ and 60℃. Larger temperature deviations and longer durations of exposure to a temperature outside the control range will cause the ink to grow deeper in color.

Figure 1: Temperature sensor code

We are working with other departments to develop new services that use this thermochromic ink and provide customers with information on temperature control status throughout the entire logistics process. We’ve combined the thermochromic ink and a product ID code containing product information to create a "temperature sensor code." The code is printed on or attached to each cardboard box with products, and a smartphone can then be used to capture an image of the code and read the color information. The smartphone then supplies information on time and location. The ability to collect such data at each stage of logistics operations allows users to monitor the temperature control status throughout the entire process.

KAWASAKIIt is a major issue when there is poor quality control for food. and that food ends up in the hands of customers by mistake. However stringent a company is in temperature control, even a single mistake can result in a loss of corporate value. Our services are targeted to eliminate such mistakes so that companies can continue to be trusted and their corporate value enhanced.
With these services, we provide customers with information on temperature control of products, time and location. If we can monitor the temperature control status in logistics and detect any instances of aberration in a controlled temperature environment, we should see a reduction in food lost during transport, which is currently an issue.

Figure 2: Temperature quality control services using the temperature sensor code

What led you to begin developing this service?

KAWASAKIInitially, food companies requested an ink that would change color when the temperature changed. They sought to understand the temperature control status at a glance because temperature management of foodstuff was an important issue.

However, those requests did not drive us to immediately develop the thermochromic ink. While we were aware of the presence of such need, we decided to develop the ink on the basis of creating a new service that would utilize it. It was at that time when Mr. Aida and I joined the team. I was in charge of designing the business from top to bottom as well as marketing, and Mr. Aida was engaged in developing the ink.

For the first 3 months or so, I was devoted to collecting information from customers to develop a business model. I asked to see the full chain of operations from production to sales, and worked with them to come up with specific ideas about how to use the ink.
In the end, we came up with a business model of services utilizing a temperature sensor code. We found ourselves returning to the original need for an ink that changes color with temperature. Subsequently, we set deadlines for PoC trials with our customers, and worked on developing the ink and building a system. At present, we are conducting PoC trials with some of our customers.

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Combining thermochromic ink and IoT, and making temperature control visible throughout the entire logistics process

What characterizes these services?

KAWASAKIWell, the thermochromic ink serves as a tool for information to be read. Although it changes color according to temperature, it remains an ink for that matter, so we decided to combine it with IoT by using smartphones. If one captures an image of the temperature sensor code with a smartphone, it can be read to receive and store the color information. Moreover, a smartphone adds information on the product location and time through its GPS function. Combined with the color information of the thermochromic ink, smartphones can record evidence pertaining to the duration for which deviation from a controlled temperate range occurred as well as the stage of the logistics process at which such an aberration occurred. Smartphones are available at reasonable cost, and bear the advantage of most people, if not anybody, being capable of using them with ease.

AIDATo date, temperature control has been conducted separately by either retail stores selling products or manufacturers, and there has been no consistent scheme of controlling or monitoring temperature in supply chains. As such, one cannot tell where in the process from production to consumption problems in temperature control arise. Therefore, to monitor individual products throughout the entire logistics process, it is crucial that temperature sensors showing the temperature status of products are available at low cost. Thermochromic ink addresses this as a temperature sensor that is inexpensive, easily handled and working consistently throughout the entire process.

How amazing it is that an ink can be used as a sensor!

KAWASAKIBefore this research, I was engaged in research of materials for semiconductor devices and had come to think of sensors as being rather expensive. It never would have occurred to me to turn ink into an inexpensive sensor. The idea emerged from amongst the diversity of people at Hitachi—there are researchers working on material, like ourselves, and there are also people engaged in devices, systems or services. Hitachi conducts business combining such variety in expertise, and this is unique on a global scale. I think our successful development stems from the strengths of the company in that when research is conducted, it spans numerous layers.

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Speedy Development under an Extremely Tight Schedule

Did you experience any hardship in development?

AIDAI would say we struggled to develop the ink, the core technology, at a speed quicker than in past research. We proposed PoC trials to customers with specific deadlines before there was even a tangible technology. This forced us to develop a controlled temperature-sensitive ink tailored to customer products.

KAWASAKIIt is true that the development period was quite short, though we can't say how long specifically. Mr. Aida was excellent to undertake the challenge, though (laugh).

AIDAThank you very much (laugh). It was the first time for me to help develop an ink that changes color with temperature. I had no prior experience of commercializing the technologies I worked on, so I was motivated by the thought that this would be the first product I could offer to society. At the PoC trials with the customers, we were urged to commercialize the technology as soon as possible. I also found that to be encouraging.

In this research, we created a hypothetical business model at an early stage and worked to develop the temperature sensor code based on the hypothesis. That was the target we set for ourselves, and our task was clear. This helped accelerate the development speed. It was necessary for Hitachi to have its own technology for thermochromic ink, the core of the service. Other than that, however, we did not fixate on developing technologies on our own and could work together with other companies. With this stance, we tested various patterns to come up with interesting technologies.

The concept from the get-go was key then, wasn't it?

KAWASAKIThat is correct. It is important to clearly show the concept of a business model at the initial stage, even if it is imperfect. At present, we are endeavoring to sophisticate our business model for commercialization and, looking back, I believe our concept was fairly to the point from the beginning (laugh). However, even if we offer a good idea from the beginning, it will not grow into a business unless we prove that it really works. When we verify whether or not a business will come from an idea, it is important to have a firm concept. A firm concept is also essential in facilitating internal support and cooperation.

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Aiming to Establish an International Standard of Temperature Control

How do you expect to extend this service going forward?

Photo: KAWASAKI Masahiro

KAWASAKIIn North America and Europe, the legal framework is being established to mandate temperature control for individual foodstuff and pharmaceutical products, from production to sales.
Temperature control by using data loggers or RFID tags has been conducted to date, but there has been no individual control, such as for every single container. Data loggers are rather expensive, so individual control using these devices bears high costs. Furthermore, as the loggers are attached to trucks for transport, etc., it is difficult to conduct control throughout the entire process.
The temperature sensor code we have developed is inexpensive, which should be another factor toward making it an international standard to solve these problems.

If standardized, anyone would be able to use this code.

AIDAThese days, all products are affixed with barcodes. If barcodes are replaced by a temperature sensor code similar to what we have developed, the quality of products will be made visible. If one can tell that products to be refrigerated have been properly controlled in refrigerators, for example, customers should be able to purchase products at ease.
We want to apply the basic model of reading codes for control in a variety of areas, not exclusively temperature control. Aside from temperature control, quality control in logistics processes involves such factors as moisture, vibration and light. It may be difficult for an ink to address all these factors, but we don't have to stick to an ink, either. If we can develop the method for such, we should be able to control total product quality.

Do you have any dreams for the future?

AIDAI have always had a hope to develop businesses, services or materials that may generate new innovation. As a first step, I want to see services using the newly developed technology start operation. Going forward, I hope to remain engaged in innovation businesses, but also something beyond inks or logistics.

KAWASAKIThrough the development, I was engaged in business that started with the customer. The experience reminded me that starting with customers has an advantage of enabling speedy development for creating a business. In the meantime, however, I can hardly abandon my dream as a researcher of changing society by conducting in-depth research of materials.
This may be difficult to achieve, but it is my ideal to create new businesses focusing on the two pillars of my dream as a researcher and businesses that start with the customer.


  • Publication: August 27, 2018
  • Professional affiliation and official position are at the time of publication.

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