Flexible Barbed Microneedle Array Electrode for Bio-Signal Monitoring: Fabrication and Characterization

Microneedle array electrodes have attracted much attention in recent years as an effective solution for surface biopotential recording. However, existing solutions have limitations in flexibility, biosafety, and manufacturing costs, which limit their wider application. To address this challenge, an innovative flexible microneedle array (FMNA) electrode is proposed. The microneedle design adopts a barbed structure. The mechanical strength of the microneedle is strong enough to penetrate the biological barrier of the outer layer and form a self-locking force. The normalized electrode-skin contact impedance is 0.59 kΩ mm⁻² at 1.02 kHz and 6.46 kΩ cm⁻² at 20 Hz. A flexible PET film is used as the substrate of the FMNA, making the electrode flexible enough to adapt to the curves of the skin surface and skin deformation caused by movement. Compared with Ag/AgCl wet electrodes, the FMNA electrode exhibited superior performance in long-term biosignal monitoring over 48 h. Under both low-speed walking and high-speed motion conditions, the electrode ensured accurate and stable ECG signal acquisition. These results highlight the potential value of flexible barbed microneedle array electrodes in health monitoring applications and demonstrate their reliability as a solution for long-term biosignal recording.