Limited output current and harsh environmental conditions are big challenges to harvesting electrical energy from triboelectric nanogenerators (TENG) in sensing applications. One contributing factor to this issue is matching the density of state between two layers of TENG for maximum charge transfer. To ensure a stable output performance, a superhydrophobic interface between the TENG's two layers has been achieved by applying a novel fluorescence enhanced hexamethyldisiloxane (HMDSO) dielectric barrier discharge (DBD) plasma. The plasma coating not only improve the hydrophobicity but also the interface contacts between the two layers of TENG and therefore a maximum charge transfer and ultra-high current density are obtained. The plasma treatment increases the surface roughness and introduces functional groups such as amino (-NH2), hydroxyl (-OH), and siloxane (-Si-O-Si) on the PMMA film, which increases the electron affinity difference between the two layers, increases humidity resistance. The modified TENG generates a maximum stable output voltage of 1400 V and a maximum current of 125 µA with a power density of 55 W/m2, which is significantly higher than those reported in previous studies. Therefore, the TENG has been used as a self-powered droplet detector with an ultra-fast response time of 1.8 ms and has the potential to be used as a self-powered humidity sensor.