A team of researchers from Harvard University’s Wyss Institute for Biologically Inspired Engineering, John A. Paulson School of Engineering and Applied Sciences (SEAS), and Department of Chemistry and Chemical Biology has developed Smart Thermally Actuating Textiles (STATs). These novel types of smart wearables induce pressure changes by electrically controlling liquid-vapor phase changes, removing the need for pneumatic tethers.
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“Our aim was to engineer robotic fabrics that can electronically sense and actuate, use integrated closed-loop feedback control to regulate themselves, and be manufactured in arbitrary shapes and large batches,” said in a statement co-first author Vanessa Sanchez, a graduate student working in Walsh’s group at the Wyss Institute and SEAS.
“STATs embody all of these features. As lightweight and unobtrusive smart fabrics, we believe they could enable a new range of robotic approaches,” she added.
To produce these STATS the team had to bring together expertise on non-wearable soft robots and innovative manufacturing techniques with a profound understanding of fluidic systems, adaptive materials, and their self-regulating properties.
The STATs were engineered as tightly sealed pouches using a commercially available woven textile membrane coated with a layer of heat-sealable thermoplastic polyurethane. By dynamically powering STATs’ electric components, an enclosed engineered fluid known as NovecTM 7000 is vaporized by heat and expands 100-fold in volume.
This enables the textiles to increase and decrease their internal pressure over a significant range. “To be able to actuate these pressure changes in a programmable fashion and allow the system to regulate itself, we manufactured electronically-conductive silver-plated threads into the fabric that form the textile-based heater and sensor elements and enable the desired temperature and pressure control inside the pouches,” said co-first author Christopher Payne, a research associate.
The team’s STATs could generate peak pressures of around 75 kPa at room temperature while interconnected STATs are able to maintain their pressure profiles independently of the others. The team now says their robotic textiles could be used in utilized in mechanotherapeutic wearables.
The study was published in Advanced Materials Technologies.