Experimental investigation on surface wettability of copper-based dry bioelectrodes

Laser micromilling technology was used to fabricate a dry bioelectrode with a surface microstructure array, which was then treated with stearic acid ethanol solution. A superhydrophobic dry bioelectrode was obtained. Based on the scanning electron microscopy results, the formation of the dry bioelectrode with a surface microstructure array had been discussed. Later, the contact angle on the bioelectrode surface was analyzed by changing the parameters such as laser processing parameters, spacing of microstructure, and the working media. The results show that the contact angle of the bioelectrode surface treated with stearic acid ethanol solution was approximately 151°, and this value was compared with the result for bioelectrodes that were not treated or placed in air. The laser power and number of scans had significant influences on the contact angle, while the scanning speed had only a slight influence. When the spacing of microstructure was in the range of 0.1-0.5 mm, the contact angle increased with a decrease in the spacing of microstructure. In addition, the contact angle on the bioelectrode with deionized water or saline water as the working media was greater than 150°. Our developed dry bioelectrode presented good hydrophobic properties to help to realize a stable measurement system over a long time, which has many applications in the detection and measurement of biological signals.