A review of giant magneto-impedance-based MEG detection technique

Figures & data

Figure 1. Block diagram of the BCI system.

Figure 2. The overall logical flow chart of this literature review.

Figure 3. Examples of MEG applications.

Table 1. Current major MEG detection techniques and their performance indicators.

Technique	Sensitivity	Magnetic shielding grade	Operating temperature	Volume	Cost	Dynamic range
SQUID	2-10fT/Hz^1/2	★★★★⋆	Extremely low temperature	Large	High	0.1 nT
SERF	<0.2fT/Hz^1/2	★★★★★	High temperature	Large	High	0.1 nT
OPM	7-10fT/Hz^1/2	★★★⋆⋆	Ordinary temperature	Medium	Medium	nT
GMI	<10fT/Hz^1/2	⋆⋆⋆⋆⋆	Ordinary temperature	Small	Low	mT

Figure 4. (a) Change in time domain waveform of the ratio of alpha/beta; (b) P300 signal under the oddball stimulation paradigm.

Figure 5. Performance comparison of various magnetic sensors.

Figure 6. The schematic diagram of the GMI effect measurement circuit.

Figure 7. Circuit structure of the GMI magnetic sensor.

Figure 8. Four different excitation types for the GMI magnetic sensor.