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 200um 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 800 μm 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.
What’s more, the new sensors do not require any special readout circuits or amplifiers, they are resistant to external noises and highly sensitive over a relatively high resistance range, making them easy to integrate into fabric-based wearables.
The paper cites sports, healthcare, rehabilitation, and robotics as different fields of application where such a soft and stretchable strain sensor could be used to measure and analyse motion dynamically.
The researchers then developed a prototype sleeve incorporating the CNT strain sensor connected through conductive silvered synthetic fibres into a stretchable compression fabric. They also devised a soft data glove (as shown worn by a pianist), able to detect the fine motions of the finger joints (the black strips on the glove are the CNT-based strain sensors) without hindering the wearer’s movements.
Manager of Materials & Components Group at Yamaha’s R&D Division, lead author Dr. Katsunori Suzuki accepted to share with eeNews Europe his insights on the sort of products Yamaha may be envisaging.
“The data gloves introduced in our paper were specifically designed to detect finger movements in a musician’s dystonia (a neurological movement disorder) under a joint study with a Japanese university” he wrote us in an email.
“We have no plan to sell it to consumers at this moment, but instead, we’ll be releasing a more robust design for Virtual Reality applications in 2016.”
Yamaha organized a live piano performance demonstration using its prototype VR glove in the 2nd Wearable Expo held last January in Tokyo, superposing the sensor data in virtual reality over virtual hands as a series of expanding and contracting spheres synchronization with the movements of the pianist’s fingers.
“We are investigating applications for the VR glove as a means to help pianists improve their skill. We think the VR glove will be suitable for music learning apps to serve real-time suggestions,” Suzuki added, “because our VR glove is much more stretchable and thinner than what’s available on the market” he wrote, taking the CyberGlove as an example.
Indeed, coming from a music instrument maker, one could easily envisage internet-connected data gloves with cloud-based analysis related to the specific instrument and partition being played.
The company also held a demonstration of VR manual assembly in a preliminary design phase using the same system, simulating an automobile engine assembly. The glove wearer would also sport an Oculus Rift to display the 3D CAD data for the automobile engine as well as a simulation of the assembler’s hands corresponding to the movement of the VR gloves.
In that case, the gloves were fitted with extra markers for hand tracking in free space.
Yamaha has started shipping sensor development kits to customers, including two sensor bands and a detachable Bluetooth wireless transmitter (enquiries at email@example.com).
For export, the company is also preparing a “wiring systems” that would connect directly an USB port to display the raw data obtained from the sensors.
Visit the stretchable strain sensor project page at https://www.y2lab.com/project/stretchable_strain_sensor/
Visit Yamaha at www.music.yamaha.com
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