A highly integrated sensing paper for wearable electrochemical sweat analysis

Wearable electrochemical sensors have attracted tremendous attention in recent years. Significant progress has been achieved, particularly in device integration. Most wearable devices are integrated on thin-film polymer, however, less attention is paid to the sweat flow at human-device interfaces, which is of great significance for continuous real-time analysis and long-term skin comfort. Here, we reported a low-cost, freestanding and disposable highly integrated sensing paper (HIS paper) for real-time analysis of sweat. By using a simple printing process, the HIS paper combining hydrophobic protecting wax, conducting electrodes, and the incorporated MXene/methylene blue (Ti3C2Tx/MB) active materials was assembled. In particular, the printed paper was folded into a multi-layer structure, in which a reasonable designed three-dimensional (3D) sweat diffusion path is established by connecting the hydrophilic regions of each layer, providing efficient pathways for the collection and diffusion of sweat along the vertical direction of the folded HIS paper. More importantly, the independent 3D position of three-electrode facilitates the decoration and fixation of enzymes, as well as the accessibility of electrolytes. In addition, a dual-channel electrochemical sensor that can simultaneously detect glucose and lactate with sensitivity of 2.4 nA μM−1 and 0.49 μA mM−1 respectively was produced based on the HIS paper. This HIS paper provides a miniaturized, low-cost and flexible solution for a range of biochemical platforms, including wearable bioelectronics. •A dual-channel electrochemical sensor is prepared based on a highly integrated sensing (HIS) paper.•HIS paper-based sensor simultaneously detects glucose and lactate with highly sensitivity.•3D sweat diffusion path vertically along the HIS paper provides fast sweat collection and transmission kinetics.•Independent 3D position of three electrodes promotes the stability and practicality of the HIS paper.•HIS paper-based sweat monitoring system is demonstrated to be used for real-time on-body sweat sensing.