Underwater Bioelectric Measurements of the Human Body:

a Method to Monitor Diver Safety

Abstract

As Japan is surrounded by the sea, many people go diving for leisure or work. However, since diving is an underwater activity in an environment where the human body is subjected to water pressure, there are always risks for divers which in the worst cases can lead to fatal accidents. To avoid such tragedies, a way to monitor the health and movements of a diver in seawater is much desired. In this paper, we have focused on bioelectric ECG and EMG measurements that have the possibility of comprehensively monitoring of diver health and behavior. We have expounded the principles and characteristics of three bioelectric measurement methods in water: 1） isolating all bioelectrodes with waterproof tape in both seawater and freshwater; 2） not isolating all bioelectrodes in freshwater; and 3） isolating some bioelectrodes in seawater （by utilizing its conductivity）. Among these methods, the third was seen to be the most suitable for bioelectric measurements in seawater where the majority of diving is conducted since the number of bioelectrodes can be reduced to around half by using the conductivity of seawater. We have thus introduced an optimal method of bioelectric measurement during dives in an actual undersea environment.