Feasibility Study of WSN System for Wireless EEG Using Sub-cm Sized 2-GHz Domino-Resonator

As a future wireless electroencephalography (EEG) system with dense sensor nodes (SNs), we propose a wireless sensor network (WSN) system with sub-cm sized 2GHz domino-resonator. The 2 GHz RF carrier signal is transmitted from the signal source to the receiver through the domino-resonator with sub-cm sized coils. Each coil is equipped with a sensor and an amplitude shift keying (ASK) modulator. Since the RF carrier signal is ASK modulated by the sensor's data as each resonator, the data of each SN can be received by the receiver of domino-resonator system. By assigning different clock (CLK) frequencies to each SN, the ASK modulated signals can be identified and demodulated separately even if the number of SNs increases. The carrier signal transmission using sub-cm sized domino-resonator is discussed with the measurements of fabricated dominoresonator without modulator and the simulation of expected degradation by the RF switch losses. The design method of CLK frequencies is also described and verified by the simulation. These results show the feasibility of proposed wireless EEG system having (1) 7 cm total communication range (RF source to receiver distance) with every 7 mm SNs placement, and (2) 150 kbps data rate for each SN. This SN configuration has no RF oscillator for each SN and no wire connection between SNs will bring low power consumption and wearability which is suited for future dense EEG monitoring system.