To achieve comfortable form factors for wireless medical devices, battery size, and thus power consumption, must be curtailed.\u00a0 Often the largest power consumption for wireless medical devices is in storing or transmitting acquired data.\u00a0 Body area networks (BAN) can alleviate power budgets by using low power transmitters to send data \u201clocally\u201d around the body to receivers that are around areas of the body that allow for larger form factors, like the wrist or the waist.\u00a0 These receivers, which have larger power budgets, can then process and store the data or send it elsewhere using higher power transmitters.<\/p>\n
Body-coupled communication (BCC) shows great potential in forming a BAN.\u00a0 Traditional two-node BCC works by forming two capacitive links between a transmitter and a receiver, creating a circuit loop.\u00a0 One of these links is created by both the transmitter and receiver capacitively coupling to the body, effectively using the body as a low-resistance channel between the respective capacitors.\u00a0 The second link is created by coupling both the transmitter and receiver coupling to the environment, or \u201cearth ground,\u201d and using it as a return path.\u00a0 Larger BANs can be made by coupling additional nodes to both the body and the environment.<\/p>\n
An application for a BAN is for an implanted EEG recorder at the head, to communicate with a base station at the waist.\u00a0 For implants, the traditional BCC will not work because capacitors E and F will short out capacitors A and D, reducing the transmission line between the transmitter and receiver to that shown in Figure 2. FSK data was sent across this channel in a variety of environments and activities including talking outdoors on a cell phone, exercising at a gym, and doing household chores.\u00a0 There was no significant difference in the BER across these different environments.<\/p>\n\n\t\t