By Amit Malewar 27 Jul, 2024
Collected at: https://www.techexplorist.com/rice-lab-foam-based-fluidic-circuits-next-gen-wearables-robotics/86583/
When envisioning the future of wearables and robotics, one may not immediately think of the foam in couch cushions. However, Rice University engineers have demonstrated that the airflow through open-cell foam’s meshlike structure can enable digital computation, analog sensing, and combined digital-analog control in soft textile-based wearable systems.
“In this work, we integrated material intelligence – the ability of materials to sense and respond to their environment – with circuit-driven logic using a surprisingly simple approach based on the flow of fluid through soft foams,” said Daniel Preston, assistant professor of mechanical engineering and corresponding author on a study about the research published in Advanced Functional Materials.
Pneumatic logic circuits in soft robotics and wearable technology have typically been designed to mimic electronic circuits, connecting individual components such as resistors, capacitors, diodes, and gates through linking elements. These traditional architectures rely on interconnected logic gates, fundamental components in digital systems that convert one or more inputs into a single output.
Previously, the Preston Innovation Laboratory introduced a method for controlling textile wearables without electronics, using pneumatic logic circuits. However, this initial approach did not fully leverage the unique properties of soft materials to optimize circuit design efficiency.
“The more complex a task or operation, the greater the number of logic gates typically required,” Preston explained.
In practical applications, this might result in the development of bulkier, costlier, and more challenging-to-produce devices that are also more prone to malfunctions. To address this issue, the researchers discovered a way to leverage pressure variances generated by air passing through the tiny pores in foam sheets to perform intricate pneumatic computations and control tasks more efficiently without requiring extensive circuitry design.
“Here, we show that the properties of soft materials themselves – such as the sponginess or porosity of foam sheets – can be leveraged to achieve fluidic control tasks such as sensing the amount of force applied by a user or converting digital pressure signals to analog signals, thereby reducing the reliance on fluidic logic gates and simplifying operation,” said Anoop Rajappan, lead author on the study and a research scientist at Rice during the course of the project.
Air density changes under pressure, unlike liquids, making the airflow modeling through foam sheets more intricate. Nevertheless, the researchers directly confronted and overcame this challenge.
“We developed a theoretical framework for analyzing gas flow through porous materials, created new experimental techniques to measure the fluidic properties of foam, and finally generated a model for the change in fluidic resistance of foam with applied force,” Rajappan said.
The scientists created fluidic resistors based on foam, which are tools used to regulate airflow in pneumatic systems, similar to how electronic resistors control current flow in electronic circuits. These resistors can form two-dimensional pneumatic logic circuits that can be integrated into wearable devices made from textiles.
“By redesigning circuit components such as resistors to leverage the fluidic properties of soft materials such as foam, we can build reliable and streamlined soft robots and wearable devices powered by pneumatics that are less dependent on heavy, bulky, or rigid components such as motors and batteries,” Rajappan said. “Wearable robotic devices could, for instance, provide assistance to users with mobility limitations, and building wearables out of textiles and powering them using compressed air can make them comfortable, lightweight, low-cost and unobtrusive for the user.”
“Our work at Rice is making real contributions across multiple fields, and I am glad so many of our students continue to do so, in academia, industry, and even their own companies, after training in our program,” Preston said.
Journal reference:
- Anoop Rajappan, Zhen Liu, Te Faye Yap, Rawand M. Rasheed, Daniel J. Preston. Embedded Fluidic Sensing and Control with Soft Open-Cell Foams. Advanced Functional Materials, 2024; DOI: 10.1002/adfm.202403379
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