Flexible Strain Sensor with Tunable Sensitivity via Microscale Electrical Breakdown in Graphene/Polyimide Thin Films

Area of Science:

• Materials Science
• Nanotechnology
• Electrical Engineering

Background:

• Carbon-based nanomaterials are crucial for flexible piezoresistive sensors.
• Previous electrical breakdown (EBD) methods faced challenges in achieving consistent traces in bulk nanocomposites.
• Developing batch-fabrication methods for sensitive flexible strain sensors is a key goal.

Purpose of the Study:

• To introduce a microscale electrical breakdown (μEBD) method for fabricating highly sensitive flexible strain sensors.
• To enable batch fabrication of localized piezoresistors with tunable shapes in graphene/polyimide (G/PI) thin films.
• To investigate the relationship between μEBD process parameters and sensor performance.

Main Methods:

• Fabrication of G/PI thin films.
• Application of a microscale electrical breakdown (μEBD) process to create localized conductive traces.
• Characterization using scanning electron microscopy (SEM) and Raman spectroscopy.
• Electromechanical testing to evaluate piezoresistivity and gauge factor.
• Tuning sensor sensitivity by varying μEBD applied current.

Main Results:

• The μEBD process generates highly porous carbonized conductive traces, enhancing piezoresistivity.
• μEBD-treated G/PI strain sensors exhibit a gauge factor over 20 times greater than untreated films.
• Sensor sensitivity is tunable by adjusting the applied current during the μEBD process.
• SEM and Raman spectroscopy confirmed the structural and compositional changes induced by μEBD.

Conclusions:

• The μEBD method offers a viable batch fabrication approach for highly sensitive flexible strain sensors.
• The high porosity of μEBD-generated traces is key to achieving enhanced piezoresistivity.
• μEBD-treated G/PI sensors show promise for applications in gesture detection, sound pressure, and airflow sensing.