Abstract
Background: Low-frequency electrical stimulation systems are being developed to convey interpersonal distance information to visually impaired individuals. However, the drive phenomenon, a reduction in signal resolution due to sweating under psychological stress, limits its practical use.
Objective: This study aimed to verify whether electrode placement directly over the C7 spinous process (reverse dermatome method) is less susceptible to the effects of sweating and improves reaction time compared to conventional placement on the dorsal forearm under visual deprivation.
Methods: Six healthy adults (mean age 58.3±4.7 years) were subjected to low-frequency electrical stimulation under two conditions—dorsal forearm and C7 spinous process—while visually deprived. Participants responded to stimulation triggered by a video simulating human approach, recorded via a 32-inch monitor. Each electrode condition was assessed five times. Signal recognition rate and skin potential were simultaneously recorded.
Results: Electrode placement over the C7 spinous process significantly maintained higher recognition accuracy during 15 minutes of use compared to dorsal forearm placement (p<0.01). Signal recognition dropped by 38.7% on the forearm but only 12.3% at the C7 site. Reaction time was significantly shorter with C7 placement (0.87±0.12s vs. 1.35±0.23s, p<0.01).
Conclusion: Placement over the C7 spinous process is less affected by sweating and mitigates the signal degradation caused by the drive phenomenon. These findings may enhance the practical application of electrical stimulation systems for guiding the visually impaired.
