Published in Bioinspiration & Biomimetics on July 30, 2026, this research presents a closed-loop controlled eel-computer biohybrid system that modulates swimming behavior of Monopterus albus through electrical stimulation of lateral-line nerves. A lightweight microelectronic backpack with stimulation electrodes was noninvasively attached to the eel to enable real-time motion control. The researchers used optimized monophasic pulse parameters (anterior lateral-line nerves: 4.0 V; posterior lateral-line nerves: 2.5 V; 10-100 Hz frequency; 30% duty cycle) to elicit directional locomotion.
The system employs a proportional-derivative (PD) feedback controller that dynamically adjusts stimulation frequency based on real-time velocity measurements to maintain predefined swimming speeds. Results showed that posterior lateral-line nerve stimulation induced forward swimming (9.0-17.8 cm/s) with a strong negative speed-frequency correlation (r = -0.96), while anterior stimulation produced backward swimming (6.9-9.5 cm/s, r = -0.89). Compared to fixed-frequency stimulation, the closed-loop approach reduced velocity deviations by 63.7% (forward) and 50.6% (backward). Body-mass-normalized external stimulation power ranged from 0.87 to 1.54 mW/g. This research demonstrates bidirectional closed-loop speed regulation in freely swimming eels, providing a compact, noninvasive control framework for adaptive, energy-efficient aquatic biohybrid robotic systems based on lateral-line-driven neural interfaces.