Effects of Electrode Diameter and Contact Material on Signal Morphology of Gastric Bioelectrical Slow Wave Recordings.

Gastric motility is governed in part by bioelectrical 'slow waves', and high-resolution electrical mapping has emerged as a clinical research tool with diagnostic potential. In this study, we aimed to determine the effects of electrode diameter and contact material on in vivo extracellular slow wave recordings to inform gastric mapping device design. Custom flexible-printed-circuit electrode arrays were designed with four electrode diameters (0.3, 1.8, 3.3, 4.8 mm; 4 × 8 array) and fabricated in four contact materials (gold, silver, copper, silver-chloride). The electrode arrays were placed on the gastric serosa in vivo in pigs and unipolar slow wave signals were simultaneously recorded from each electrode. Propagation, signal morphology, and noise were quantified to determine which electrodes produced signals with the highest signal-to-noise ratio (SNR) and gradient, which is a preferred metric for detection and analytical algorithms. Electrodes of diameters 0.3 and 1.8 mm recorded significantly higher signal gradients than 3.3 and 4.8 mm (p < 0.05). Silver-chloride electrodes recorded a significantly higher gradient than all other materials (p < 0.05), with no significant differences between gold, silver, and copper electrodes. Electrodes of diameters 1.8 and 3.3 mm recorded significantly higher SNR than 0.3 mm (p < 0.05). Electrodes with a diameter of 1.8 mm provided an optimal combination to maximize the signal gradient and SNR, and silver-chloride electrodes yielded the highest signal gradient. These results can now inform gastric mapping device design, particularly minimally-invasive devices where electrode size is critical.