Collaborators from Nanyang Technology University and Singapore-Hu Alliance for Research and Enterprise (SHARE) have developed a 3-printed triboelectric nanogenerator with a new stretchability record. 

The new device has a 2500% stretchability compared to the highest value of 1000%. The lead authors are Kaushik Parida, Gurunathan Thangavel, and Pooi See Lee who published their findings in Nature Communications.

The vast applications of triboelectric nanogenerator (TENGs) include wearable electronic devices. TENGs obtain their energy from ambient mechanical movements such as finger tapping. The challenge for TENGs involve the different elasticity of the two main layers: the triboelectric layer and the conductor. These two layers get separated after repeated stretching. 

This challenge was resolved by using the same elastic material (polyurethane acrylate, or PUA) for both the two layers. Liquid metal particles and silver flakes were added to increase the conductivity. The hydrogen bonds in the PUA can handle extreme stretching as these break and reform to support the target stretchability. The device maintains high conductivity as a conductive liquid metal is released by the liquid metal particle in order to connect the separated silver flakes in the PUA matrix. 

"The researchers also demonstrated that the nanogenerator can be cut apart into separate pieces, and yet still almost completely regain its original performance after a healing process consisting of 24 hours of heating," according to Phys. 

All the components in the nanogenerator were printed using a 3D printer. Studies prior to this used the 3D printer only on the triboelectric layer because of the limitations of stretchability of most elastomeric materials. 

Different applications for the nanogenerator as an energy harvester because of its conductivity and high stretchability, as well as simple process of fabrication using 3D printing. These applications include LEDs and sensors.