Abstract-Flexible and giant terahertz modulation based on ultra strain sensitive conductive polymer composites

Qiwu Shi, Ke Tian, Hongfu Zhu, Zi-run Li, Li-Guo,  Zhu Hua,  Deng Wanxia Huang, Qiang Fu,

https://pubs.acs.org/doi/10.1021/acsami.9b21890

Dynamic tuning of terahertz (THz) wave has a great potential application for smart THz devices, such as switching, modulation, sensor, and so on. However, realization of flexible THz modulation with high efficiency is rarely observed, which is nearly absent from the booming development and demands on flexible electronics. Here, we report a flexible THz modulation based on conductive polymer composites composed of thermoplastic polyurethane (TPU) and conductive particles (Ni). By designing the additive content of Ni particles, such flexible layer exhibits resistivity change of 6-7 orders under tensile strain, due to the formation of electron transport channel provided by in situ evolution of Ni network. It could be used to dynamically control THz transmission with giant modulation depth of around 96%, at high strain operation (up to around 58.5%). Moreover, these characteristics are demonstrated to be available for highly tension sensitive THz spectroscopy and imaging. This work opens up a connection between flexible polymer based composites and THz dynamic device. It proposes an unprecedented flexible THz modulation with giant tuning efficiency, and provides a scheme for contactless and passive tension sensor.

OT-LUNA Blog-Creating a Self-Measuring Smart Structure with a Fully Distributed Strain Rosette

https://lunainc.com/creating-self-measuring-smart-structure-fully-distributed-strain-rosette/

With the integration of new materials into applications and structures, developing strain profiles to characterize material behavior, conduct structural health monitoring and enable in-situ non-destructive testing requires a different measurement solution.

High-Definition Fiber Optic Sensors (HD-FOS) have been frequently utilized for highly spatially-resolved strain measurements on a wide variety of materials and complex part geometries.

Luna has demonstrated that a single fiber can be configured into a rosette geometry, allowing planar and shear strains to be fully characterized. By arranging a single fiber optic sensor in an extended rosette pattern, distributed principal strains and their orientations can be determined at any location within the pattern.

This research focused on integrating fiber optic sensors into composite structures and culminated with embedding a distributed rosette pattern into a composite helicopter rotor blade. The rotor blade was shown to be effective in measuring distributed strains on the order of ±500 microstrain along its curved surfaces, resulting in a highly desirable smart structure capable of measuring its own mechanical integrity.