3D-printed carbon nanotube sensors present potential for sensible well being monitoring

Polymer-based conductive nanocomposites, notably these incorporating carbon nanotubes, are extremely promising for the event of versatile electronics, smooth robotics and wearable units. Nevertheless, CNTs are troublesome to work with as they have a tendency to agglomerate, making it onerous to acquire a uniform dispersion. Furthermore, standard strategies restrict management over CNT distribution and form.

To beat these challenges, researchers are turning to additive manufacturing (AM) or 3D printing strategies, akin to vat photopolymerization (VPP), which provide wonderful design freedom with excessive printing accuracy.

On this technique, a lightweight is used to selectively treatment and harden layers of an ink inside a vat, progressively constructing a 3D object. Regardless of its benefits, it additionally poses a number of challenges. The presence of CNTs impacts the printability and curing properties of the inks. Furthermore, concurrently reaching excessive stretchability and electrical conductivity is a significant problem.

Now, a analysis group led by Professor Keun Park and Affiliate Professor Soonjae Pyo from the Division of Mechanical System Design Engineering at Seoul Nationwide College of Science and Expertise in Korea has efficiently fabricated extremely stretchable, electrically conductive CNT-nanocomposites, utilizing VPP-type 3D printing.

“Our new CNT-nanocomposites are optimized particularly for VPP-based processes, permitting fabrication of extremely advanced 3D buildings,” explains Prof. Park. “We additionally used these supplies to additively manufacture new piezoresistive sensors and built-in them right into a wearable well being monitoring machine.”

Their research is printed within the journal Composite Constructions.

The group first ready polymer nanocomposite inks by uniformly dispersing multi-walled carbon nanotubes (MWCNTs) into an aliphatic urethane diacrylate (AUD) resin, with concentrations starting from 0.1 to 0.9 weight%. To realize uniform dispersion, they agitated the combination utilizing ultrasonic waves. The ready inks have been then analyzed to find out the optimum printing situations.

Subsequent, the group additively manufactured take a look at specimens utilizing the assorted inks and examined them for his or her mechanical and electrical properties, in addition to printing decision (the minimal thickness that may be printed). Outcomes confirmed that the formulation with 0.9 weight% CNT supplied one of the best stability of properties.

It may stretch as much as 223% of its authentic size earlier than breaking, whereas nonetheless reaching a outstanding electrical conductivity of 1.64 ×10⁻³ S/m, surpassing that of beforehand reported supplies. It additionally achieved a printing decision of 0.6 mm.

To exhibit sensible applicability, the researchers used the optimized CNT nanocomposite to 3D print versatile triply periodic minimal floor (TPMS)-based piezoresistive sensors that confirmed excessive sensitivity and dependable efficiency. Importantly, they built-in these sensors into an insole to create a smart-insole platform.

Utilizing this platform, the group may monitor the strain distribution on the backside of the foot in actual time, detecting totally different human actions and postures.

“The developed smart-insole machine demonstrates the potential of our CNT nanocomposites for 3D printing the subsequent era of extremely stretchable and conductive supplies,” stated Prof. Pyo. “We consider these supplies will likely be indispensable for wearable well being displays, versatile electronics and sensible textiles.”