Micro Dispensing: From Semiconductors To Sushi

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.

Yes, printed sushi – the food. IHI Aerospace is involved in developing a commercial space platform that could be used, among other things, to carry civilians into orbit. The company is already looking ahead to enhancing all levels of the experience, including meals.

To make sushi practical in orbit, where every gram of mass comes at a steep price, IHI had to look beyond specialty chefs, sharp knives, and coolers of fish and seafood. The solution? Printing the sushi with a lightweight countertop micro dispensing system. By integrating a Nordson EFD PICO Pµlse piezo 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 (see figure 1).

Fig. 1: Uni sushi printed using the Nordson EFD PICO Pµlse jetting system.

Sushi and space

The adventurers looking for the thrill of orbital spaceflight will expect an unforgettable experience, from start to finish. They will want something more exotic than just a sandwich. Ready to explore creative possibilities, IHI Aerospace reached out to Yamagata University, which has a strong aerospace engineering program and an equally well-regarded program in the culinary arts. Brainstorming resulted in the concept of serving sushi in orbit. The question was how.

Sushi is the quintessential Japanese cuisine. There is no lengthy list of ingredients or array of tricky culinary techniques to mask any mistakes. It hinges on utter simplicity – fresh ingredients, balanced flavors, and beautiful presentation. That very simplicity makes it challenging to prepare successfully, especially in space.

In a strategic decision that addressed both the culinary and food prep challenges, the Yamagata 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. This is particularly beneficial for uni, which in solid form degrades in a day or two from buttery and delicious to slimy and bitter. 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. Integrated with a compact robot, the right fluid dispenser could deposit the paste in a way that mimics the appearance of a traditional sushi protein. The unit could be installed in a galley and produce various types of sushi with the press of a button (see figure 2).

Fig. 2: Printable sushi machine consists of a compact robot arm integrated with non-contact piezoelectric micro dispensing system using the PICO Pµlse jet valve and Toµch controller.

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. Further, in the event of blockage, the nozzles needed to be cleanable.

From a culinary standpoint there was another wrinkle to the cleaning issue. 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.

To tackle these challenges and build their prototype, the Yamagata University team turned to Nordson EFD Japan.

The solution

When the IHI/Yamagata University design team reached out, the Nordson EFD Japan applications engineers were surprised, then engaged by the unique use case. Although the product being dispensed was a bit unorthodox, the task at hand was ultimately the same as usual: find an efficient way to reliably dispense a precise volume of fluid at a specified rate.

And the way the Nordson EFD team developed the solution was also the same: consult with the customer to determine requirements, identify, and address the challenges, specify a system, and test to guarantee accurate and reliable performance.

Ideally, the uni paste would be deposited without disturbing the bed of rice. This called for a jetting valve. The Nordson EFD team recommended the Nordson EFD PICO Pµlse jet valve system. The system uses a piezoelectric actuator for smooth, accurate non-contact or jet dispensing of even very thick fluids.

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. From an operational perspective, piezo valves provide the benefits of long lifetimes and high reliability.

In addition, the PICO Pµlse is a modular product, offering 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 Tomch 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.

With the system specified, the real work began – evaluating the solution in the Nordson EFD Japan dedicated test facility. The Nordson team assembled a testbed and exercised it under a variety of conditions to ensure accurate, reliable operation.

Results

The combined team of IHI Aerospace, Yamagata University, and Nordson EFD Japan built a prototype automated dispensing system capable of printing 3D sushi. The product looks artistic and consistent, time after time (see figure 3). The PICO piezoelectric dispensing system is so reliable that the Yamagata University team successfully demonstrated it at a major Japanese tradeshow, serving treats to visiting dignitaries.

Fig. 3: Uni sushi printed by the micro dispensing system looks fresh and appetizing.

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.

Conclusion

The PICO Pµlse jet valve tackled the extraordinary application of printing sushi, but that just scratches the surface of its capabilities. This micro dispensing system combines high accuracy and repeatability with great versatility, making it highly effective for a host of applications both within and beyond standard industrial niches. Bring us your most challenging applications and we will find a solution. We developed a system capable of printing sushi. Just imagine what we can do for you.