IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING (IN SUBMISSION) 1 Blind Source Separation for the Superconducting

Abstract—Magnetic signals from brain responses are very weak compared to those from its surroundings. A system based on SQUIDs (Superconducting Quantum Interference Devices) was constructed to detect these fields. This system is novel in that it contains a superconducting lead (Pb) surface which shields the sensors from external magnetic fields. Since the signals of interest still have a low signal to noise (S/N) ratio, and each sensor receives a mixture of signals from different parts of the brain, we used a blind source separation (BSS) algorithm to separate the various sources. This increased the S/N ratio sufficiently to allow us to perform single-trial analysis of the data, including wavelet denoising