Tailoring polypyrrole film characteristics with multi-step oxygen plasma treatment for high-performance strain sensors: Impact on bonding, microstructure, and electrical responsivity

We investigate the impact of oxygen plasma treatment (O₂ PT) on the performance of polypyrrole (PPy)/polydimethylsiloxane strain sensors. Utilizing a three-step chemical oxidative polymerization method for PPy growth, we explore various durations of O₂ PT (0, 30, 60, and 90 s) during intermediate growth stages. Through analyses using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, we elucidate the relationship between O₂ PT, structural changes, and strain sensor performance. Sensor devices plasma-treated for 30 s exhibit exceptional characteristics: a gauge factor of 432 at 50% strain and a response time of 50 ms under quasi-step function strain variation from 0% to 1% in 40 ms. These results underscore the pivotal role of O₂ PT in enhancing the performance of PPy-based strain sensors, providing insights for advanced sensor design and fabrication techniques.