New strain sensor takes inspiration from butterfly wings to optimize sensitivity and stretchability

Designers of wearable health monitoring devices often need to consider the balance between sensitivity and stretchability. Is it better to create a strain sensor that is stretchy but is less precise, or a more precise sensor that can’t stretch as much? Taking inspiration from butterfly wings, Teng et al. developed a strain sensor that achieves the best of both worlds.

The new strain sensor exhibits a high gauge factor of approximately 515, an extensive tensile range of 0% to 96%, a rapid response time of 300 milliseconds, and high durability as by its stable performance over more than 60,000 cycles where the device was loaded and unloaded from 10 to 20% strain. The authors found they could use the sensor for human motion and for recognizing small changes in facial expressions, showing its potential for flexible electronics and artificial intelligence.

“This work is significant because it combines high sensitivity, broad stretchability, and durability in one flexible sensor,” author Fu-Rui Teng said. “The biomimetic design —inspired by butterfly wings and coupled with the integration of multiwall carbon nanotubes modified with iridium nanoparticles and a surface platinum layer — contributes to exceptional sensing performance.”

To create their sensor, the team used atomic layer deposition to modify carbon nanotubes with iridium nanoparticles. They then immersed actual butterfly wings within adhesive film, drop-coating the nanotube-iridium mixture onto the cured film and then depositing a platinum layer using magnetron sputtering. The team validated the sensor’s composition, structure, and functionality using multiple techniques, including scanning electron microscopy and X-ray diffraction.

Further work includes optimizing the sensor’s material composition to further enhance sensitivity and stretchability.

Source: “Robust biomimetic strain sensor based on butterfly wing-derived skeleton structure,” by Fu-Rui Teng, Si-Chen Tan, Jia-Bin Fang, Tao-Qing Zi, Di Wu, Ai-Dong Li, Applied Physics Letters (2024). The article can be accessed at https://doi.org/10.1063/5.0229819 .