Monolithically integrated flexible sensing systems with multi-dimensional printable MXene electrodes

Abstract

Manufacturing flexible integrated sensing systems by combining versatile printable inks and diverse printing techniques allows for the monolithic utilization of the electrochemical/sensing performance of individual devices. Herein, we developed an integration strategy for fabricating high-performance flexible integrated sensing systems by utilization of multi-dimensional printable MXene electrodes. With branched polyethyleneimine (BPEI) serving as joining sites and flexible spacers, the flexible printed electrodes exhibited weak self-restacking, high interlayer charge carrier transporting ability, and remarkably enhanced mechanical robustness. As a result, the printed micro-supercapacitors (MSCs) showed ultrahigh areal capacitance (3783.53 mF cm⁻² at a scan rate of 1 mV s⁻¹), outstanding flexibility (stable after 1000 bending/release cycles), high energy density (99.4 μW h cm⁻²) and high power density (18 mW cm⁻²). Besides, the printed strain sensor board displayed high sensitivity over a wide working strain range (e.g., gauge factor: 11 781.5 in the 41–52% strain range). These results represent the record values in most state-of-the-art devices. In addition, an all-in-one flexible sensing system integrated with both an MSC and a strain sensor on a flexible substrate is demonstrated, which exhibited exceptional sensitivity to body movements. This proposed strategy paves a high-efficiency pathway toward high-performance, monolithically integrated electronics.