Portable printer developed for fabrication of origami devices

In the present times, origami-inspired three-dimensional (3D) devices are being developed, where a single sheet of material is folded into small devices. These devices are being developed for medical applications like stents or surgical tools; agricultural devices like soil-sensors; and efficient spacecraft radiators or solar arrays that are used in space technology. Along with innovation, it is also important to focus on sustainable technology that can fulfill human needs and is adaptable to environmental changes.

There is a growing demand for on-demand sensor fabrication, which does not require complex infrastructure. Sensor deployment in resource-limited environments such as agriculture fields, health care settings, disaster sites, and space missions is also an emerging requirement. Keeping sustainability and reduction of electronic waste in mind, researchers are trying to focus on sustainable design of disposable devices that can fabricate low-cost, resource-efficient internet of things (IoT) sensors. However, the presently available approaches for 3D device fabrication have certain limitations, including the portability factor, which makes them impractical for on-site use.

Now, a team of researchers led by Associate Professor Hiroki Shigemune from Shibaura Institute of Technology, Japan, along with Dr. Yuhi Watanabe and Dr. Atsushi Matsushita from Shibaura Institute of Technology, Japan, have developed a new portable, multimaterial printer for on-site fabrication of origami devices using electrowetting on dielectric (EWOD) technology, a digital microfluidic method, that controls and manipulates the position, shape, and behavior of liquid droplets on a surface without the need of any external valve or pump. This study is published in the journal ACS Applied Materials & Interfaces.

“We developed a palm-sized portable and compact printer that leverages EWOD technology to independently control and print both conductive and insulating liquids. This system precisely deposits functional inks onto paper substrates using only electrical ON/OFF signals, without mechanical components or external pumps, facilitating on-site fabrication of origami devices,” explains Dr. Shigemune.

The researchers optimized the printing conditions for both structural and electrode inks independently and in an integrated manner. The integration did not compromise the functionality in any manner. They applied the proposed approach to fabricating an origami stretchable strain sensor and a respiration sensor.

Notably, the strain sensor exhibited stable performance even after 1,000 cycles of deformation and respiration sensor showed stable signal responses during repeated breath detection. The durability under 1,000 cycles of stretching, combined with the flexibility and absorbency of paper substrates, highlights the environmental compatibility of this system.

“Our proposed system can help produce site-specific sensors and devices with customized shapes and functions for portable IoT device manufacturing platforms for deployment in fields such as agriculture and health care,” says Dr. Shigemune.

As the system is very minimal, comprising of only paper, ink, and a small-scale control device, it is easy to transport and store. This allows sensor fabrication in off-grid environments, catering to human-needs in remote locations, like disaster response scenarios or extraterrestrial settings. In certain, unfavorable situations where large equipment cannot be deployed, essential sensors and electronic devices can be manufactured on demand, providing rapid response capabilities under limited-resource conditions.

The printer has strong potential for multiple real-world applications. It can be used to make sensor-integrated smart-agricultural packaging on-site to match the size or impact conditions of harvested fruit, allowing quality-based optimization. It can be used to develop wearable, custom-fabricated health care devices that can be attached to masks or garments for monitoring respiration or movement to control infections and monitor the health of elders.

“Overall, our study lays the foundation for development of low-cost, deployable, and eco-friendly sensors. The proposed novel fabrication paradigm contributes to the sustainable and flexible manufacturing practices in the fields of smart agriculture, medical IoT, and personalized health care,” concludes Dr. Shigemune.