Graphene-Based Transparent Flexible Strain Gauges with Tunable Sensitivity and Strain Range

Area of Science:

• Materials Science
• Nanotechnology
• Flexible Electronics

Background:

• Graphene oxide (GO) can be assembled into transparent conducting films.
• Reduced graphene oxide (rGO) films on flexible substrates offer potential for wearable electronics.
• Cracking of rGO films can induce piezoresistivity for sensing applications.

Purpose of the Study:

• To develop transparent and flexible strain gauges based on cracked reduced graphene oxide films.
• To investigate the effect of manufacturing conditions on the performance of rGO strain gauges.
• To demonstrate the application of these strain gauges in e-skin.

Main Methods:

• Assembling GO monolayers at an interface to form films on polydimethylsiloxane (PDMS) membranes.
• Reducing GO to rGO using hydroiodic acid (HI) vapor under controlled conditions (30 s and 60 s).
• Inducing cracks in rGO films through prestraining and characterizing their piezoresistive response.

Main Results:

• Reduction for 30 s yielded parallel cracks, resulting in strain gauges with a usable range >0.2 and a gauge factor (GF) of 20-100.
• Reduction for 60 s created through-cracks, leading to higher GF (800-16,000) but a reduced usable strain range (<0.01).
• A resistor model explained the observed behavior, and gauges demonstrated stable response up to >1 kHz, detecting human body strains.

Conclusions:

• The sensitivity and strain range of rGO-based strain gauges are tunable by controlling the film's crack structure during fabrication.
• These flexible, transparent strain gauges show promise for applications in wearable electronics and e-skin.
• The developed rGO strain gauges offer a viable platform for sensitive and stable strain detection.