Self-Powered cobalt nanocluster decorated flexible graphene based Tribo-Sensors for respiratory diagnosis of critical asthma patient

Self-powered ultrafast sensors have received much attention for sustainable operation without any external power source in the Internet of Things (IoT) platform. This paper proposes faster responsive, highly sensitive triboelectric nanogenerator (TENG) sensors based on few layered nitrogen-doped graphene anchored with cobalt nanocluster (Co-N-Gr) to detect the relative concentration of target species, their proximity analysis, and monitor malfunction of human respiration in real-time. Herein, to understand the sensing mechanism, P-type behaviour of this active material is verified under the FET platform by reducing the leakage current density via the implementation of dual dielectric gate (NiO (200 nm)-SiO₂ (10 nm)) oxides leading to better control over channel mobility. The device exhibits maximum sensitivity of around 4722 % at zero bias conditions with excellent response and recovery time of 1.16 s and 1.39 s, respectively which falls within the range of standard human breathing frequency. The triboelectric nature of the sensor device at 1 V bias under natural breathing exhibits a high sensitivity (39.56 %) towards relative humidity of 10–90 % with excellent stability over 13 h. In addition, our TENG sensor is highly sensitive towards NO_x content upto ppb level which can improve reliability towards asthma detection as NO_x content is relatively higher in asthma patients. This approach provides an integrated platform not only towards selective detection of NO_x content as well as to identify the individual breathing strength. Furthermore, as-fabricated self-powered device demonstrates its potential in differentiating various respiratory status and has the capability to detect acute exacerbation of chronic obstructive pulmonary disease (AECOPD) via a distinct pattern recognition. Therefore, the work paves the way to design a low-cost flexible device fabrication on Kapton substrate integrable with wearable appliances for commercialization.