The phrase “micro fluid dispensing” is generally associated with applications like medical device assembly or battery manufacturing. It certainly doesn’t conjure up visions of sushi—at least not yet. If engineers at IHI Aerospace and Yamagata University have their way, though, 3D printed sushi will be served to space tourists as they circle in low Earth orbit.

IHI Aerospace is involved in developing a commercial space platform that could be used to carry civilians into orbit. The company is already looking ahead to enhancing all levels of the experience, including meals—in particular, sushi. IHI had to look beyond specialty chefs, sharp knives, and coolers of fish and seafood and decided to print the sushi with a lightweight countertop micro dispensing system. 

Considering that adventurers looking for the thrill of orbital spaceflight will expect an unforgettable experience which includes something more exotic than just a sandwich, IHI Aerospace reached out to Yamagata University, which has a strong aerospace engineering program and an equally well-regarded culinary arts program. After some brainstorming, the University team chose proteins in a paste form rather than as solid fish or seafood. 

Uni (sea urchin) and other fish pastes are common food items in Japan and many parts of the world. Thus, the concept of sushi made with uni paste is familiar. Pastes have benefits for both quality and logistics. The proteins are harvested and packed at the peak of flavor. Plus, packaged pastes are shelf stable with no leftover food waste to generate odor. Protein pastes are also compatible with non-contact micro fluid dispensing technology, making it possible to automate the sushi preparation. 

The Challenges

Developing printable sushi was an innovative concept and presented a number of challenges. The application required a specific volume of uni paste to be dispensed on a bed of rice in a specific pattern and location. Uni paste is a high-viscosity fluid that requires well-controlled pressure to dispense. The nozzle needed to be wide enough to discourage blockages but narrow enough to provide controlled deposition. In addition, the goal of the program was to create a system to produce four different kinds of printed sushi in paste form: uni, white fish, crab, and shrimp. The system needed to be able to toggle from one to another without flavor residue. Further, in the event of blockage, the nozzles needed to be cleanable.

To tackle these challenges and build their prototype, the Yamagata University team turned to Nordson EFD Japan. By integrating a Nordson EFD PICO Pulse piezo jetting valve technology with a compact robot, the group created a precision micro fluid dispensing system capable of printing sushi that rivals products from the local sushi bar. The unit can be installed in a galley and produce various types of sushi with the press of a button.

Piezo valves are very high-resolution and reliable, with long lifetimes. These characteristics enable the user to tailor stroke length, precisely controlling the amount dispensed. This characteristic equips the PICO Pµlse jet valve to optimize deposition to achieve a uniform appearance for sushi pastes with different consistencies. 

The PICO Pµlse is a modular product, offering great flexibility and enabling it to be configured ideally for each application. A tool-free latch enables the fluid body to be exchanged rapidly and easily. Rapid exchanges are as useful during prototyping as they are once the product is in operation. The ability to swap out fluid carrying parts quickly allows the valve to serve its purpose of dispensing different types of pastes and being easy to clean.

The IHI Aerospace/ Yamagata University team combined the PICO Pµlse valve with the Nordson EFD PICO Touch valve controller and fluid reservoir for an end-to-end solution that combined ease of integration with accurate, reliable operation.

The next step was to choose the optimal nozzle to handle the protein pastes. Nordson EFD recommended a flat nozzle with a 300-micron orifice. This nozzle has a wide enough aperture to ensure smooth, controlled deposition of the protein pastes while minimizing the risk of blockages. This nozzle was covered with a special hydrophilic coating used for sticky fluids. It reduced surface tension of the wetted pathway for improved micro dispensing consistency.

While printable sushi for orbital meals is an admittedly exotic use case, printable food in general could have a much broader impact. The Yamagata University team, for example, hopes to continue to explore the technology for food service in facilities like hospitals, nursing homes, and long-term care facilities.

For more information: 

Nordson EFD

Nordson Pico Pulse Valves 

IHI Aerospace

Yamagata University

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