Past Results, Present Trends, and Future Challenges in Intrabody Communication

Table 1

Main differences between galvanic and capacitive coupling techniques.

	Galvanic coupling	Capacitive coupling
Type of signal injected	Alternating current flow	Electrostatic potential
Electrodes	One pair of TX electrodes and another pair of RX electrodes connected to the body	In TX and RX, the signal electrodes are connected to the human body, and the ground electrodes remain floating towards the external air
Contact	Direct contact with the human body is required	Direct contact with the human body is not required
Signal coupling	Differential	It needs an external common ground
Signal paths	The dominant signal path is the human body	Two signal paths: a direct path through the human body and a return path through the external ground
Attenuation	Dependent on bioelectric properties of tissues	Dependent on external environmental conditions
Data rate	Low data rates	Higher data rates
Interference	Sensitive to body part and placement of electrodes	Sensitive to other nearby devices that can be capacitively coupled