Abstract: Human bio-signals are important indicators for disease diagnosis and clinical treatment. The medical microneedle array electrode (MAE) is an important sensor to measure bio-signals of human body. However, MAE has not been clinical application due to its complex fabrication process and poor mechanical strength. In this work, a metal MAE is one-step fabricated by low speed wire electrical discharge machine (LSWEDM) for bio-signals monitoring, including ECG, EMG and EEG. 316L stainless steel is cut and fabricated into the pyramid MAE by LSWEDM. MAE consisted of a 10×10 microneedles array with a height of 930 μm, bottom width of 400 μm and tip radius of 10 μm. MAE had good mechanical strength without bending or broken under repeated insertions. MAE could easily penetrate through the stratum corneum of skin and formed microchannels in the skin. Transepidermal water loss (TEWL) test demonstrated that skin could be recovered in 40 min after skin penetration by MAE. ECG signals recorded by MAE exhibited very similar waveform with standard Ag/AgCl electrode. EMG signals collected by MAE could reflect the motion of the muscle with higher amplitude. MAE could accurately and completely record the EEG signals under eye opening-closing and blinking. MAE could directly detect the bio-signals without skin preparation, exhibited good potential for bio-signals monitoring and suitable for long-term monitoring.

Key words: microneedle array, skin penetration, EEG, ECG, EMG