Soft lightweight data gloves fit VR and musicians

June 16, 2016 // By Julien Happich
In cooperation with the Shizuoka University (Japan), Yamaha Corporation is investigating the use of millimeter-long multi-walled carbon nanotubes (MWCNTs) in elastomeric strain sensors for wearables.

The music instrument maker is not only looking into virtual reality applications where lightweight and soft data gloves could replace bulky and rigid alternatives, but would also naturally fit such data gloves to musicians, whose fine finger motion could be better monitored with thin and stretchable fabric-based sensors.

In a recent ACS Sensors paper titled "Rapid-Response, Widely Stretchable Sensor of Aligned MWCNT/Elastomer Composites for Human Motion Detection", the Japanese researchers reported about thin CNT-based strain sensors designed to be integrated into textile-based wearable sensing systems (be it at arm, hand, or finger level).

They used a sheet of uni-directionally aligned MWCNTs impregnated with an elastomer (urethane resin), making electrodes with a conductive paste on each extremity to form sensors a few centimetres long and stretchable up to twice their original length. Only a few micrometres thick (up to 200μm with an added layer to support the device's elasticity), the strain sensors obtained had a response time under 15ms with a gauge factor exceeding 10 (high sensitivity).

As well as repeatability, the strain sensors also exhibited a very high resistance variation linearity. The researchers attribute this to the use of very long CNT bundles (with MWCNTs 300 to 800μm long). While elongation creates cleavages and gaps that increase the resistance, because the MWCNTs are so long, neighbouring CNTs remain in contact as they slide and rub against each other, ensuring a much more progressive decrease in conductivity less affected by created gaps than if their length were on the order of micrometres. Upon contraction, the MWCNTs reorganize more densely and the original resistance is restored.