Long term biopotential recording by body conformable photolithography fabricated low cost polymeric microneedle arrays

We report a novel approach for the fabrication of a user friendly functional device with dry electrodes for the measurement of biopotentials (electrocardiograph or ECG, electroencephalogram or EEG) that allows extended measurement time, reduced preparation time and less motion induced artifacts compared to wet gel based commercial electrodes. The dry micro-electrode arrays were fabricated by the UV maskless lithography in the grayscale or back-exposure modes using a biocompatible polymer SU-8. This produced conical shaped, mechanically robust micro-needles on a flexible polymer substrate which conforms to the body contours thereby greatly reducing the motion artifacts. The device was tested in vivo on human subjects and compared with the currently utilized wet gel based Ag/AgCl electrodes. It demonstrated comparable performance in capturing ECG and EEG signals. The electrodes were tested for long duration (48 h) without any signs of degradation. This device can be utilized for long term as well as remote health monitoring of the subjects.