Light-Stable, Ultrastretchable Wearable Strain Sensors for Versatile Plant Growth Monitoring

Area of Science:

• Materials Science
• Plant Biology
• Biotechnology

Background:

• Wearable electronics offer applications in plant monitoring, but existing strain sensors face limitations in sensing range, transparency, and stability.
• Previous research developed transparent, conjugated polymer-based strain sensors with over 400% operating strain for plant growth measurement.

Purpose of the Study:

• To develop second-generation plant strain sensors with enhanced photostability and stretchability for broader plant growth monitoring applications.
• To improve device stability under illumination and increase the strain sensing range through advanced fabrication techniques.

Main Methods:

• Fabrication of strain sensors using room-temperature-cured Au-C-Al electrodes for improved photostability.
• Application of sensors to various plant organs (leaves, stems, cotyledons, fruits) of tomatoes and cucumbers.
• Utilizing direct ink writing for patterning and encapsulation to boost stretchability and achieve a wider strain sensing range.

Main Results:

• The new sensors demonstrate significantly improved stability under direct light illumination.
• Successful monitoring of elongation and radial growth rates in tomatoes and cucumbers across day/night cycles.
• Achieved a record 1000% apparent operating nominal strain using a long-horseshoe pattern, validated on grass leaves.

Conclusions:

• The developed second-generation plant strain sensors overcome previous limitations, offering enhanced stability and unprecedented stretchability.
• These sensors enable precise monitoring of plant growth, even in very young plant organs like cucumber cotyledons.
• The findings pave the way for more sophisticated plant growth monitoring systems using wearable electronic devices.