A single screen-printable multifunctional active ink platform based on tin cobalt oxide decorated carbon nanofibers for energy storage and sensing applications

This study emphasises the formulation of a single screen-printable multifunctional active ink platform. This formulated conductive ink simplifies the fabrication of three distinct microelectronic devices: micro-supercapacitors, humidity sensors, and electrochemical sensors. The conductive ink platform was developed by combining pseudocapacitive spinel SnCo 2 O 4 with conductive carbon nanofibers (CNF). The screen-printed SnCo 2 O 4 /CNF (SC-3) micro-supercapacitor electrode revealed both pseudocapacitive and EDLC charge-storage mechanisms. This electrode demonstrated outstanding performance for microscale energy applications with an areal capacitance of 673.8 ± 3.1 mF cm − 2 (SC-3), an energy density of 93.58 ± 1.5 µWh cm − 2 and a power density of 1.353 ± 3.0 mW cm − 2 ( n = 3, RSD < 1%). In conjunction with microsupercapacitors, this conductive ink presents remarkable potential for sensing applications. The developed humidity sensor exhibits excellent stability, fast response/recovery times (38/56 s), a low hysteresis (1.46%) and a wide detection range (11–97%). In an electrochemical sensor, the modified SC-3/SPE exhibited excellent electrochemical behaviour for the detection of Naproxen. The SC-3/SPE sensor has a wide drug concentration range of 1 µM to 500 µM. The long-term stability of the sensor implies efficient naproxen measurement in tablet and synthetic urine samples, with an RSD of 3.53% (± 0.72). The interplay between the CNF framework and redox-active SnCo 2 O 4 contributes to improvement in a conductive ink platform. This current work tackles the shortcomings of conventional standalone energy storage and sensing devices. The results highlight the introduction of a scalable, affordable, multifunctional conductive ink formulation for next-generation miniaturised microelectronics.